LTC2268-12/
LTC2267-12/LTC2266-12
12-Bit, 125Msps/105Msps/
80Msps Low Power Dual ADCs
Features
Description
n
n
n
The LTC®2268-12/LTC2267-12/LTC2266-12 are 2-channel,
simultaneous sampling 12-bit A/D converters designed
for digitizing high frequency, wide dynamic range signals.
They are perfect for demanding communications applications with AC performance that includes 70.6dB SNR and
88dB spurious free dynamic range (SFDR). Ultralow jitter
of 0.15psRMS allows undersampling of IF frequencies with
excellent noise performance.
n
n
n
n
n
n
n
n
n
2-Channel Simultaneous Sampling ADC
70.6dB SNR
88dB SFDR
Low Power: 292mW/238mW/200mW Total,
146mW/119mW/100mW per Channel
Single 1.8V Supply
Serial LVDS Outputs: 1 or 2 Bits per Channel
Selectable Input Ranges: 1VP-P to 2VP-P
800MHz Full Power Bandwidth S/H
Shutdown and Nap Modes
Serial SPI Port for Configuration
Pin Compatible 14-Bit and 12-Bit Versions
40-Pin (6mm × 6mm) QFN Package
Applications
Communications
Cellular Base Stations
n Software Defined Radios
n Portable Medical Imaging
n Multichannel Data Acquisition
n Nondestructive Testing
n
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
DC specs include ±0.3LSB INL (typ), ±0.1LSB DNL (typ)
and no missing codes over temperature. The transition
noise is a low 0.3LSBRMS.
The digital outputs are serial LVDS to minimize the number of data lines. Each channel outputs two bits at a time
(2-lane mode). At lower sampling rates there is a one bit
per channel option (1-lane mode). The LVDS drivers have
optional internal termination and adjustable output levels
to ensure clean signal integrity.
The ENC+ and ENC– inputs may be driven differentially
or single-ended with a sine wave, PECL, LVDS, TTL, or
CMOS inputs. An internal clock duty cycle stabilizer allows high performance at full speed for a wide range of
clock duty cycles.
Typical Application
1.8V
VDD
CH.2
ANALOG
INPUT
ENCODE
INPUT
OVDD
0
–10
S/H
S/H
12-BIT
ADC CORE
12-BIT
ADC CORE
DATA
SERIALIZER
OUT1A
–20
OUT1B
–30
OUT2A
OUT2B
DATA
CLOCK
OUT
PLL
FRAME
GND
OGND
226812 TA01
SERIALIZED
LVDS
OUTPUTS
AMPLITUDE (dBFS)
CH.1
ANALOG
INPUT
LTC2268-12, 125Msps,
2-Tone FFT, f IN = 70MHz and 75MHz
1.8V
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
10
20
30
40
FREQUENCY (MHz)
50
60
226812 TA01b
22687612fa
1
LTC2268-12/
LTC2267-12/LTC2266-12
Absolute Maximum Ratings
Pin Configuration
(Note 1)
OUT1A–
OUT1A+
GND
SDO
PAR/SER
VREF
GND
SENSE
VDD
TOP VIEW
VDD
Supply Voltages
VDD, OVDD................................................. –0.3V to 2V
Analog Input Voltage (AIN+, AIN–,
PAR/SER, SENSE) (Note 3)..............–0.3V to (VDD+0.2V)
Digital Input Voltage (ENC+, ENC–, CS,
SDI, SCK) (Note 4)..................................... –0.3V to 3.9V
SDO (Note 4)............................................. –0.3V to 3.9V
Digital Output Voltage................... –0.3V to (OVDD+0.3V)
Operating Temperature Range
LTC2268C, 2267C, 2266C......................... 0°C to 70°C
LTC2268I, 2267I, 2266I........................ –40°C to 85°C
Storage Temperature Range.................... –65°C to 150°C
40 39 38 37 36 35 34 33 32 31
+
1
30 OUT1B+
–
2
29 OUT1B–
AIN1
AIN1
VCM1 3
28 DCO+
REFH 4
27 DCO–
REFH 5
26 OVDD
41
GND
REFL 6
25 OGND
REFL 7
24 FR+
VCM2 8
23 FR–
AIN2+ 9
22 OUT2A+
–
21 OUT2A–
AIN2
10
OUT2B +
OUT2B –
GND
SDI
SCK
CS
ENC–
ENC+
VDD
VDD
11 12 13 14 15 16 17 18 19 20
UJ PACKAGE
40-LEAD (6mm × 6mm) PLASTIC QFN
TJMAX = 150°C, θJA = 32°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
order information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2268CUJ-12#PBF
LTC2268CUJ-12#TRPBF
LTC2268UJ-12
40-Lead (6mm × 6mm) Plastic QFN
0°C to 70°C
LTC2268IUJ-12#PBF
LTC2268IUJ-12#TRPBF
LTC2268UJ-12
40-Lead (6mm × 6mm) Plastic QFN
–40°C to 85°C
LTC2267CUJ-12#PBF
LTC2267CUJ-12#TRPBF
LTC2267UJ-12
40-Lead (6mm × 6mm) Plastic QFN
0°C to 70°C
LTC2267IUJ-12#PBF
LTC2267IUJ-12#TRPBF
LTC2267UJ-12
40-Lead (6mm × 6mm) Plastic QFN
–40°C to 85°C
LTC2266CUJ-12#PBF
LTC2266CUJ-12#TRPBF
LTC2266UJ-12
40-Lead (6mm × 6mm) Plastic QFN
0°C to 70°C
LTC2266IUJ-12#PBF
LTC2266IUJ-12#TRPBF
LTC2266UJ-12
40-Lead (6mm × 6mm) Plastic QFN
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
22687612fa
2
LTC2268-12/
LTC2267-12/LTC2266-12
converter
Characteristics l denotes the specifications which apply over the full operating
The
temperature range, otherwise specifications are at TA = 25°C. (Note 5)
LTC2268-12
PARAMETER
CONDITIONS
Resolution
(No Missing Codes)
MIN
l
12
TYP
LTC2267-12
MAX
MIN
TYP
LTC2266-12
MAX
MIN
12
TYP
MAX
UNITS
12
Bits
Integral Linearity Error
Differential Analog Input
(Note 6)
l
–1
±0.3
1
–1
±0.3
1
–1
±0.3
1
LSB
Differential Linearity Error
Differential Analog Input
l
–0.5
±0.1
0.5
–0.4
±0.1
0.4
–0.4
±0.1
0.4
LSB
Offset Error
(Note 7)
l
–12
±3
12
–12
±3
12
–12
±3
12
mV
Gain Error
Internal Reference
External Reference
l
–2.4
–0.9
–0.9
0.6
–2.4
–0.9
–0.9
0.6
–2.4
–0.9
–0.9
0.6
%FS
%FS
Offset Drift
±20
±20
±20
µV/°C
Full-Scale Drift
Internal Reference
External Reference
±30
±10
±30
±10
±30
±10
ppm/°C
ppm/°C
Gain Matching
External Reference
±0.2
±0.2
±0.2
%FS
±3
±3
±3
mV
0.3
0.3
0.3
LSBRMS
Offset Matching
Transition Noise
External Reference
analog
input l denotes the specifications which apply over the full operating temperature range, otherwise
The
specifications are at TA = 25°C. (Note 5)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
VIN
Analog Input Range (AIN+ – AIN–)
1.7V < VDD < 1.9V
l
VIN(CM)
Analog Input Common Mode (AIN+ – AIN–)/2
Differential Analog Input (Note 8)
l
VCM – 100mV
VCM
VCM +100mV
V
VSENSE
External Voltage Reference Applied to SENSE
External Reference Mode
l
0.625
1.25
1.3
V
IINCM
Analog Input Common Mode Current
Per Pin, 125Msps
Per Pin, 105Msps
Per Pin, 80Msps
l
IIN1
Analog Input Leakage Current (No Encode)
0 < AIN+, AIN– < VDD
l
–1
1
µA
IIN2
PAR/SER Input Leakage Current
0 < PAR/SER < VDD
l
–3
3
µA
IIN3
SENSE Input Leakage Current
0.625 < SENSE < 1.3V
l
–6
6
µA
tAP
Sample-and-Hold Acquisition Delay Time
0
0.15
tJITTER
Sample-and-Hold Acquisition Delay Jitter
CMRR
Analog Input Common Mode Rejection Ratio
BW-3B
Full Power Bandwidth
Figure 6 Test Circuit
1 to 2
VP–P
155
130
100
µA
µA
µA
ns
psRMS
80
dB
800
MHz
22687612fa
3
LTC2268-12/
LTC2267-12/LTC2266-12
digital
accuracy l denotes the specifications which apply over the full operating temperature range,
The
otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Note 5)
LTC2268-12
SYMBOL PARAMETER
CONDITIONS
SNR
5MHz Input
70MHz Input
140MHz Input
Spurious Free Dynamic Range
2nd or 3rd Harmonic
SFDR
S/(N+D)
LTC2267-12
MIN
TYP
MIN
TYP
MIN
TYP
l
69.6
70.6
70.6
70.3
69.2
70.6
70.5
70.3
69.4
70.6
70.5
70.3
dBFS
dBFS
dBFS
5MHz Input
70MHz Input
140MHz Input
l
75
88
85
82
76
88
85
82
76
88
85
82
dBFS
dBFS
dBFS
Spurious Free Dynamic Range
4th Harmonic or Higher
5MHz Input
70MHz Input
140MHz Input
l
84
90
90
90
82
90
90
90
84
90
90
90
dBFS
dBFS
dBFS
Signal-to-Noise Plus Distortion
Ratio
5MHz Input
70MHz Input
140MHz Input
l
69
70.6
70.4
70
68.8
70.6
70.4
70
69
70.4
70.3
69.9
dBFS
dBFS
dBFS
Crosstalk
10MHz Input
–105
dBc
Signal-to-Noise Ratio
MAX
–105
MAX
LTC2266-12
–105
MAX
UNITS
internal
reference characteristics
The
l denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Note 5)
PARAMETER
CONDITIONS
VCM Output Voltage
IOUT = 0
MIN
TYP
MAX
0.5 • VDD – 25mV
0.5 • VDD
0.VDD + 25mV
VCM Output Temperature Drift
VCM Output Resistance
–600µA < IOUT < 1mA
IOUT = 0
4
1.225
Ω
1.25
VREF Output Temperature Drift
1.275
–400µA < IOUT < 1mA
VREF Line Regulation
1.7V < VDD < 1.9V
V
ppm/°C
±25
VREF Output Resistance
V
ppm/°C
±25
VREF Output Voltage
UNITS
7
Ω
0.6
mV/V
digital
inputs and outputs l denotes the specifications which apply over the full operating
The
temperature range, otherwise specifications are at TA = 25°C. (Note 5)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
ENCODE INPUTS (ENC+, ENC–)
DIFFERENTIAL ENCODE MODE (ENC– NOT TIED TO GND)
VID
Differential Input Voltage
(Note 8)
VICM
Common Mode Input Voltage
Internally Set
Externally Set (Note 8)
l
1.1
VIN
Input Voltage Range
ENC+, ENC– to GND
l
0.2
RIN
Input Resistance
(See Figure 10)
CIN
Input Capacitance
l
0.2
V
1.2
1.6
V
V
3.6
V
10
kΩ
3.5
pF
SINGLE-ENDED ENCODE MODE (ENC– TIED TO GND)
VIH
High Level Input Voltage
VDD =1.8V
l
VIL
Low Level Input Voltage
VDD =1.8V
l
VIN
Input Voltage Range
ENC+ to GND
l
RIN
Input Resistance
(See Figure 11)
CIN
Input Capacitance
1.2
V
0
0.6
V
3.6
V
30
kΩ
3.5
pF
22687612fa
4
LTC2268-12/
LTC2267-12/LTC2266-12
digital
inputs and outputs l denotes the specifications which apply over the full operating
The
temperature range, otherwise specifications are at TA = 25°C. (Note 5)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL INPUTS (CS, SDI, SCK in Serial or Parallel Programming Mode. SDO in Parallel Programming Mode)
VIH
High Level Input Voltage
VDD =1.8V
l
VIL
Low Level Input Voltage
VDD =1.8V
l
IIN
Input Current
VIN = 0V to 3.6V
l
CIN
Input Capacitance
1.3
V
–10
0.6
V
10
µA
3
pF
200
Ω
SDO OUTPUT (Serial Programming Mode. Open Drain Output. Requires 2kΩ Pull-Up Resistor if SDO is Used)
ROL
Logic Low Output Resistance to GND
VDD =1.8V, SDO = 0V
IOH
Logic High Output Leakage Current
SDO = 0V to 3.6V
COUT
Output Capacitance
–10
l
10
µA
3
pF
DIGITAL DATA OUTPUTS
VOD
Differential Output Voltage
100Ω Differential Load, 3.5mA Mode
100Ω Differential Load, 1.75mA Mode
l
l
247
125
350
175
454
250
mV
mV
VOS
Common Mode Output Voltage
100Ω Differential Load, 3.5mA Mode
100Ω Differential Load, 1.75mA Mode
l
l
1.125
1.125
1.25
1.25
1.375
1.375
RTERM
On-Chip Termination Resistance
Termination Enabled, OVDD =1.8V
V
V
100
Ω
POWER
REQUIREMENTS l denotes the specifications which apply over the full operating temperature
The
range, otherwise specifications are at TA = 25°C. (Note 9)
LTC2268-12
SYMBOL PARAMETER
CONDITIONS
LTC2267-12
LTC2266-12
MIN
TYP
MAX
MIN
TYP
MAX
MIN
TYP
MAX
VDD
Analog Supply Voltage (Note 10)
l
1.7
1.8
1.9
1.7
1.8
1.9
1.7
1.8
1.9
V
OVDD
Output Supply Voltage (Note 10)
l
1.7
1.8
1.9
1.7
1.8
1.9
1.7
1.8
1.9
V
IVDD
Analog Supply Current Sine Wave Input
l
146
165
116
129
96
109
mA
IOVDD
Digital Supply Current
2-Lane Mode, 1.75mA Mode
2-Lane Mode, 3.5mA Mode
l
l
16
30
20
34
16
29
19
33
15
29
18
32
mA
mA
PDISS
Power Dissipation
2-Lane Mode, 1.75mA Mode
2-Lane Mode, 3.5mA Mode
l
l
292
317
333
358
238
261
266
292
200
225
229
254
mW
mW
PSLEEP
Sleep Mode Power
1
1
1
mW
PNAP
Nap Mode Power
70
70
70
mW
20
20
20
mW
PDIFFCLK Power Increase with Differential Encode Mode Enabled
(No Increase for Sleep Mode)
UNITS
timing
characteristics l denotes the specifications which apply over the full operating temperature
The
range, otherwise specifications are at TA = 25°C. (Note 5)
LTC2268-12
SYMBOL PARAMETER
CONDITIONS
MIN
fS
Sampling Frequency
(Notes 10, 11)
l
5
tENCL
ENC Low Time (Note 8)
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
l
l
3.8
2
tENCH
Analog Supply Current
Duty Cycle Stabilizer Off
Duty Cycle Stabilizer On
l
l
3.8
2
tAP
Sample-and-Hold
Acquisition Delay Time
TYP
LTC2267-12
MAX
MIN
125
5
4
4
100
100
4.52
2
4
4
100
100
4.52
2
0
TYP
LTC2266-12
MAX
MIN
105
5
4.76
4.76
100
100
5.93
2
4.76
4.76
100
100
5.93
2
0
TYP
MAX
UNITS
80
MHz
6.25
6.25
100
100
ns
ns
6.25
6.25
100
100
ns
ns
0
ns
22687612fa
5
LTC2268-12/
LTC2267-12/LTC2266-12
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DIGITAL DATA OUTPUTS (RTERM = 100Ω Differential, CL = 2pF to GND on Each Output)
tSER
Serial Data Bit Period
1/(8 • fS)
1/(7 • fS)
1/(6 • fS)
1/(16 • fS)
1/(14 • fS)
1/(12 • fS)
2-Lanes, 16-Bit Serialization
2-Lanes, 14-Bit Serialization
2-Lanes, 12-Bit Serialization
1-Lane, 16-Bit Serialization
1-Lane, 14-Bit Serialization
1-Lane, 12-Bit Serialization
s
tFRAME
FR to DCO Delay
(Note 8)
l
0.35 • tSER
0.5 • tSER
0.65 • tSER
s
tDATA
DATA to DCO Delay
(Note 8)
l
0.35 • tSER
0.5 • tSER
0.65 • tSER
s
tPD
Propagation Delay
(Note 8)
l
0.7n + 2 • tSER
1.1n + 2 • tSER
1.5n + 2 • tSER
s
tR
Output Rise Time
Data, DCO, FR, 20% to 80%
0.17
ns
tF
Output Fall Time
Data, DCO, FR, 20% to 80%
0.17
ns
DCO Cycle-Cycle Jitter
tSER = 1ns
Pipeline Latency
60
psP-P
6
Cycles
SPI PORT TIMING (Note 8)
tSCK
SCK Period
tS
Write Mode
Readback Mode, CSDO = 20pF, RPULLUP = 2k
l
l
40
250
ns
ns
CS to SCK Setup Time
l
5
ns
tH
SCK to CS Setup Time
l
5
ns
tDS
SDI Setup Time
l
5
ns
tDH
SDI Hold Time
l
5
tDO
SCK falling to SDO Valid
Readback Mode, CSDO = 20pF, RPULLUP = 2k
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All voltage values are with respect to GND with GND and OGND
shorted (unless otherwise noted).
Note 3: When these pin voltages are taken below GND or above VDD,
they will be clamped by internal diodes. This product can handle input
currents of greater than 100mA below GND or above VDD without latchup.
Note 4: When these pin voltages are taken below GND they will be
clamped by internal diodes. When these pin voltages are taken above
VDD they will not be clamped by internal diodes. This product can handle
input currents of greater than 100mA below GND without latchup.
Note 5: VDD = OVDD = 1.8V, fSAMPLE = 125MHz (LTC2268), 105MHz
(LTC2267), or 80MHz (LTC2266), 2-lane output mode, differential ENC+/
ENC– = 2VP-P sine wave, input range = 2VP-P with differential drive, unless
otherwise noted.
l
ns
125
ns
Note 6: Integral nonlinearity is defined as the deviation of a code from a
best fit straight line to the transfer curve. The deviation is measured from
the center of the quantization band.
Note 7: Offset error is the offset voltage measured from –0.5 LSB when
the output code flickers between 0000 0000 0000 and 1111 1111 1111 in
2’s complement output mode.
Note 8: Guaranteed by design, not subject to test.
Note 9: VDD = OVDD = 1.8V, fSAMPLE = 125MHz (LTC2268), 105MHz
(LTC2267), or 80MHz (LTC2266), 2-lane output mode, ENC+ = singleended 1.8V square wave, ENC– = 0V, input range = 2VP-P with differential
drive, unless otherwise noted. The supply current and power dissipation
specifications are totals for the entire chip, not per channel.
Note 10: Recommended operating conditions.
Note 11: The maximum sampling frequency depends on the speed grade
of the part and also which serialization mode is used. The maximum serial
data rate is 1000Mbps so tSER must be greater than or equal to 1ns.
22687612fa
6
LTC2268-12/
LTC2267-12/LTC2266-12
TIMING Diagrams
2-Lane Output Mode, 16-Bit Serialization
tAP
ANALOG
INPUT
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tDATA
tFRAME
FR–
FR+
tSER
tPD
tSER
–
OUT#A
OUT#A+
OUT#B–
OUT#B+
D3
D1
DX*
0
D11
D9
D7
D5
D3
D1
DX*
0
D11
D9
D7
D2
D0
DY*
0
D10
D8
D6
D4
D2
D0
DY*
0
D10
D8
D6
SAMPLE N-6
SAMPLE N-5
SAMPLE N-4
226812 TD01
*DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT
VERSIONS OF THESE A/Ds. DURING NORMAL NON-OVERRANGED OPERATION DX AND DY ARE SET TO
LOGIC 0. SEE THE DATA FORMAT SECTION FOR MORE DETAILS.
2-Lane Output Mode, 14-Bit Serialization
tAP
ANALOG
INPUT
N+2
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tDATA
tFRAME
FR–
FR+
tSER
tPD
tSER
OUT#A–
OUT#A+
OUT#B–
OUT#B+
D5
D3
D1
DX*
D11
D9
D7
D5
D3
D1
DX*
D11
D9
D7
D5
D3
D1
DX*
D11
D9
D7
D4
D2
D0
DY*
D10
D8
D6
D4
D2
D0
DY*
D10
D8
D6
D4
D2
D0
DY*
D10
D8
D6
SAMPLE N-6
SAMPLE N-5
SAMPLE N-4
NOTE THAT IN THIS MODE, FR+/FR– HAS TWO TIMES THE PERIOD OF ENC+/ENC–
SAMPLE N-3
226812 TD02
*DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT
VERSIONS OF THESE A/Ds. DURING NORMAL NON-OVERRANGED OPERATION DX AND DY ARE SET TO
LOGIC 0. SEE THE DATA FORMAT SECTION FOR MORE DETAILS.
22687612fa
7
LTC2268-12/
LTC2267-12/LTC2266-12
TIMING Diagrams
2-Lane Output Mode, 12-Bit Serialization
tAP
ANALOG
INPUT
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tDATA
tFRAME
FR+
FR–
tPD
tSER
–
OUT#A
OUT#A+
OUT#B–
OUT#B+
tSER
D7
D5
D3
D1
D11
D9
D7
D5
D3
D1
D11
D9
D7
D6
D4
D2
D0
D10
D8
D6
D4
D2
D0
D10
D8
D6
SAMPLE N-6
SAMPLE N-5
SAMPLE N-4
226812 TD03
1-Lane Output Mode, 16-Bit Serialization
tAP
ANALOG
INPUT
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tFRAME
FR–
FR+
tDATA
tSER
tPD
tSER
OUT#A–
OUT#A+
DX*
DY*
0
0
SAMPLE N-6
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
SAMPLE N-5
OUT#B+, OUT#B– ARE DISABLED
D1
D0
DX*
DY*
0
0
D11
D10
SAMPLE N-4
D9
D8
226812 TD04
*DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT
VERSIONS OF THESE A/Ds. DURING NORMAL NON-OVERRANGED OPERATION DX AND DY ARE SET TO
LOGIC 0. SEE THE DATA FORMAT SECTION FOR MORE DETAILS.
22687612fa
8
LTC2268-12/
LTC2267-12/LTC2266-12
TIMING Diagrams
1-Lane Output Mode, 14-Bit Serialization
tAP
ANALOG
INPUT
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tFRAME
FR–
FR+
OUT#A–
OUT#A+
tDATA
tSER
tPD
D1
D0
DX*
tSER
DY*
SAMPLE N-6
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
DX*
DY*
SAMPLE N-5
D11
D10
D9
D8
SAMPLE N-4
226812 TD05
OUT#B+, OUT#B– ARE DISABLED
*DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT
VERSIONS OF THESE A/Ds. DURING NORMAL NON-OVERRANGED OPERATION DX AND DY ARE SET TO
LOGIC 0. SEE THE DATA FORMAT SECTION FOR MORE DETAILS.
1-Lane Output Mode, 12-Bit Serialization
tAP
ANALOG
INPUT
N+1
N
tENCH
tENCL
ENC–
ENC+
tSER
DCO–
DCO+
tFRAME
FR–
FR+
OUT#A–
OUT#A+
tDATA
tSER
tPD
D3
D2
D1
tSER
D0
SAMPLE N-6
OUT#B+, OUT#B– ARE DISABLED
D11
D10
SAMPLE N-5
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
D11
D10
D9
SAMPLE N-4
226812 TD06
22687612fa
9
LTC2268-12/
LTC2267-12/LTC2266-12
TIMING Diagrams
SPI Port Timing (Readback Mode)
tDS
tS
tDH
tSCK
tH
CS
SCK
tDO
SDI
SDO
R/W
A6
A5
A4
A3
A2
A1
A0
XX
D7
HIGH IMPEDANCE
XX
D6
XX
D5
XX
D4
XX
D3
XX
D2
XX
XX
D1
D0
SPI Port Timing (Write Mode)
CS
SCK
SDI
SDO
R/W
HIGH IMPEDANCE
A6
A5
A4
A3
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
226812 TD07
22687612fa
10
LTC2268-12/
LTC2267-12/LTC2266-12
Typical Performance Characteristics
LTC2268-12: Integral
Nonlinearity (INL)
1.0
0
0.8
0.8
–10
0.6
0.6
0.4
0.4
0.2
0
–0.2
–0.4
0
–0.2
–0.4
–0.6
–0.8
–0.8
–1.0
–1.0
1024
2048
3072
OUTPUT CODE
4096
–30
0.2
–0.6
0
–20
AMPLITUDE (dBFS)
DNL ERROR (LSB)
1.0
INL ERROR (LSB)
LTC2268-12: 8k Point FFT,
fIN = 5MHz, –1dBFS, 125Msps
LTC2268-12: Differential
Nonlinearity (DNL)
–70
–80
0
1024
2048
3072
OUTPUT CODE
4096
–110
–120
LTC2268-12: 8k Point FFT,
fIN = 30MHz, –1dBFS, 125Msps
0
LTC2268-12: 8k Point FFT,
fIN = 70MHz, –1dBFS, 125Msps
0
–10
–20
–20
–20
–30
–30
–30
–60
–70
–80
AMPLITUDE (dBFS)
–10
–50
–40
–50
–60
–70
–80
–80
–110
–120
–110
–120
60
0
10
20
30
40
FREQUENCY (MHz)
50
226812 G04
10000
70
SNR (dBFS)
12000
COUNT
AMPLITUDE (dBFS)
–40
–50
8000
–80
6000
–90
–100
4000
10
20
30
40
FREQUENCY (MHz)
50
60
226812 G07
0
2041
69
68
67
2000
0
60
71
14000
–30
50
72
16000
–20
20
30
40
FREQUENCY (MHz)
LTC2268-12: SNR vs Input
Frequency, –1dBFS, 2V Range,
125Msps
18000
0
–70
10
226812 G06
LTC2268-12: Shorted Input
Histogram
–10
–60
0
226812 G05
LTC2268-12: 8k Point 2-Tone FFT,
fIN = 70MHz, 75MHz, –1dBFS,
125Msps
–110
–120
60
LTC2268-12: 8k Point FFT,
fIN = 140MHz, –1dBFS, 125Msps
–70
–110
–120
50
60
–60
–90
–100
20
30
40
FREQUENCY (MHz)
50
–40
–90
–100
10
20
30
40
FREQUENCY (MHz)
–50
–90
–100
0
10
226812 G03
–10
–40
0
226812 G02
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
–60
–90
–100
226812 G01
0
–40
–50
2042
2043
2044
OUTPUT CODE
2045
226812 G08
66
0
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
350
226812 G09
22687612fa
11
LTC2268-12/
LTC2267-12/LTC2266-12
Typical Performance Characteristics
LTC2268-12: SFDR vs Input
Frequency, –1dBFS, 2V Range,
125Msps
95
110
LTC2268-12: SFDR vs Input Level,
fIN = 70MHz, 2V Range, 125Msps
90
75
80
70
SNR (dBc AND dBFS)
SFDR (dBc AND dBFS)
80
dBc
60
50
40
30
0
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
0
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
350
40
30
0
–60
0
226812 G10
226812 G12
LTC2268-12: IVDD vs Sample Rate,
5MHz Sine Wave Input, –1dBFS
IOVDD vs Sample Rate, 5MHz Sine
Wave Input, –1dBFS, 5pF on Each
Data Output
–50
–40
–30
–20
INPUT LEVEL (dBFS)
–10
0
226812 G50
LTC2268-12: SNR vs SENSE,
fIN = 5MHz, –1dBFS
72
30
160
dBc
50
10
10
65
60
20
20
70
dBFS
70
90
85
SFDR (dBFS)
80
dBFS
100
LTC2268-12: SNR vs Input Level,
fIN = 70MHz, 2V Range, 125Msps
2-LANE, 3.5mA
71
150
1-LANE, 3.5mA
130
2-LANE, 1.75mA
10
120
70
SNR (dBFS)
20
IOVDD (mA)
IVDD (mA)
140
69
68
1-LANE, 1.75mA
67
110
100
0
25
50
75
100
SAMPLE RATE (Msps)
0
125
0
25
50
75
100
SAMPLE RATE (Msps)
0.6
LTC2267-12: Integral
Nonlinearity (INL)
1.0
0
0.8
0.8
–10
0.6
0.6
0.4
0.4
–0.2
–0.4
0
–0.2
–0.4
–0.6
–0.8
–0.8
–1.0
–1.0
1024
2048
3072
OUTPUT CODE
4096
226812 G21
1.2
1.3
LTC2267-12: 8k Point FFT,
fIN = 5MHz, –1dBFS, 105Msps
–30
0.2
–0.6
0
0.9
1
1.1
SENSE PIN (V)
–20
AMPLITUDE (dBFS)
DNL ERROR (LSB)
1.0
0
0.8
226812 G15
LTC2267-12: Differential
Nonlinearity (DNL)
0.2
0.7
226812 G51
226812 G53
INL ERROR (LSB)
66
125
–40
–50
–60
–70
–80
–90
–100
0
1024
2048
3072
OUTPUT CODE
4096
226812 G22
–110
–120
0
10
20
30
40
FREQUENCY (MHz)
50
226812 G23
22687612fa
12
LTC2268-12/
LTC2267-12/LTC2266-12
Typical Performance Characteristics
0
LTC2267-12: 8k Point FFT,
fIN = 70MHz, –1dBFS, 105Msps
0
–10
–10
–20
–20
–20
–30
–30
–30
–40
–50
–60
–70
–80
AMPLITUDE (dBFS)
–10
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
LTC2267-12: 8k Point FFT,
fIN = 30MHz, –1dBFS, 105Msps
–40
–50
–60
–70
–80
–40
–50
–60
–70
–80
–90
–100
–90
–100
–90
–100
–110
–120
–110
–120
–110
–120
0
10
20
30
40
FREQUENCY (MHz)
50
0
10
20
30
40
FREQUENCY (MHz)
226812 G24
0
71
14000
–30
–40
12000
–70
70
SNR (dBFS)
COUNT
10000
8000
–80
6000
–90
–100
4000
67
2000
0
10
20
30
40
FREQUENCY (MHz)
0
2044
50
2045
2046
2047
OUTPUT CODE
226812 G27
95
110
100
90
80
75
LTC2267-12: SFDR vs Input Level,
fIN = 70MHz, 2V Range, 105Msps
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
350
LTC2267-12: IVDD vs Sample Rate,
5MHz Sine Wave Input, –1dB
130
dBFS
120
80
70
60
dBc
50
40
110
100
30
90
20
70
0
226812 G49
90
SFDR (dBc AND dBFS)
SFDR (dBFS)
66
2048
226812 G28
LTC2267-12: SFDR vs Input
Frequency, –1dBFS, 2V Range,
105Msps
85
69
68
IVDD (mA)
AMPLITUDE (dBFS)
72
16000
–20
50
226812 G26
18000
–60
20
30
40
FREQUENCY (MHz)
10
LTC2267-12: SNR vs Input
Frequency, –1dBFS, 2V Range,
105Msps
LTC2267-12: Shorted Input
Histogram
–10
–50
0
226812 G25
LTC2267-12: 8k Point 2-Tone FFT,
fIN = 70MHz, 75MHz, –1dBFS,
105Msps
–110
–120
50
LTC2267-12: 8k Point FFT,
fIN = 140MHz, –1dBFS, 105Msps
10
65
0
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
350
226812 G30
0
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
0
226812 G32
80
0
25
50
75
SAMPLE RATE (Msps)
100
226812 G54
22687612fa
13
LTC2268-12/
LTC2267-12/LTC2266-12
Typical Performance Characteristics
LTC2267-12: SNR vs SENSE,
fIN = 5MHz, –1dBFS
LTC2266-12: Integral
Nonlinearity (INL)
71
INL ERROR (LSB)
SNR (dBFS)
70
69
68
67
66
0.6
0.7
0.8
0.9
1
1.1
SENSE PIN (V)
1.2
1.0
1.0
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0
–0.2
–0.4
–0.4
–0.6
–0.8
0
1024
2048
3072
OUTPUT CODE
–1.0
4096
LTC2266-12: 8k Point FFT,
fIN = 5MHz, –1dBFS, 80Msps
0
LTC2266-12: 8k Point FFT,
fIN = 30MHz, –1dBFS, 80Msps
0
–10
–20
–20
–20
–30
–30
–30
–60
–70
–80
AMPLITUDE (dBFS)
–10
–50
–40
–50
–60
–70
–80
–70
–80
–110
–120
–110
–120
–110
–120
40
0
10
20
30
FREQUENCY (MHz)
226812 G43
–10
–20
–20
–30
–30
–70
16000
14000
12000
–40
–50
–60
–70
10000
8000
–80
6000
–90
–100
–90
–100
4000
–110
–120
–110
–120
–80
0
10
20
30
FREQUENCY (MHz)
40
226812 G46
40
18000
COUNT
–60
20
30
FREQUENCY (MHz)
LTC2266-12:
Shorted Input Histogram
0
–10
–40
10
226812 G45
LTC2266-12: 8k Point 2-Tone FFT,
fIN = 70MHz, 75MHz, –1dBFS,
80Msps
LTC2266-12: 8k Point FFT,
fIN = 140MHz, –1dBFS, 80Msps
–50
0
226812 G44
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
40
LTC2266-12: 8k Point FFT,
fIN = 70MHz, –1dBFS, 80Msps
–60
–90
–100
20
30
FREQUENCY (MHz)
4096
–40
–90
–100
10
2048
3072
OUTPUT CODE
–50
–90
–100
0
1024
226812 G42
–10
–40
0
226812 G41
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
–0.2
–0.8
226812 G35
0
0.2
–0.6
–1.0
1.3
DNL ERROR (LSB)
72
LTC2266-12: Differential
Nonlinearity (DNL)
2000
0
10
20
30
FREQUENCY (MHz)
40
226812 G47
0
2052
2053
2054
2055
OUTPUT CODE
2056
226812 G48
22687612fa
14
LTC2268-12/
LTC2267-12/LTC2266-12
Typical Performance Characteristics
LTC2266-12: SNR vs Input
Frequency, –1dBFS, 2V Range,
80Msps
LTC2266-12: SFDR vs Input
Frequency, –1dBFS, 2V Range,
80Msps
72
95
71
90
70
85
LTC2266-12: SFDR vs Input Level,
fIN = 70MHz, 2V Range, 80Msps
110
69
80
68
75
67
70
66
65
dBFS
90
SFDR (dBc AND dBFS)
SFDR (dBFS)
SNR (dBFS)
100
80
70
dBc
60
50
40
30
20
10
0
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
350
0
50
100 150 200 250 300
INPUT FREQUENCY (MHz)
226812 G35a
226812 G49
110
350
72
PEAK-TO-PEAK JITTER (ps)
100
SNR (dBFS)
IVDD (mA)
70
69
68
80
67
0
20
40
60
SAMPLE RATE (Msps)
80
226812 G55a
66
DCO Cycle-Cycle Jitter vs Serial
Data Rate
300
71
90
0
226812 G52
LTC2266-12: SNR vs SENSE,
fIN = 5MHz, –1dBFS
LTC2266-12: IVDD vs Sample Rate,
5MHz Sine Wave Input, –1dBFS
70
0
–80 –70 –60 –50 –40 –30 –20 –10
INPUT LEVEL (dBFS)
350
250
200
150
100
50
0.6
0.7
0.8
0.9 1.0 1.1
SENSE PIN (V)
1.2
1.3
226812 G55
0
0
200
400
600
800
SERIAL DATA RATE (Mbps)
1000
226812 G52a
22687612fa
15
LTC2268-12/
LTC2267-12/LTC2266-12
Pin Functions
AIN1+ (Pin 1): Channel 1 Positive Differential Analog
Input.
AIN1– (Pin 2): Channel 1 Negative Differential Analog
Input.
VCM1 (Pin 3): Common Mode Bias Output, Nominally Equal
to VDD/2. VCM should be used to bias the common mode
of the analog inputs of channel 1. Bypass to ground with
a 0.1µF ceramic capacitor.
REFH (Pins 4,5): ADC High Reference. Bypass to pins 6, 7
with a 2.2µF ceramic capacitor and to ground with a 0.1µF
ceramic capacitor.
REFL (Pins 6,7): ADC Low Reference. Bypass to pins 4, 5
with a 2.2µF ceramic capacitor and to ground with a 0.1µF
ceramic capacitor.
VCM2 (Pin 8): Common Mode Bias Output, Nominally Equal
to VDD/2. VCM should be used to bias the common mode
of the analog inputs of channel 2. Bypass to ground with
a 0.1µF ceramic capacitor.
AIN2+ (Pin 9): Channel 2 Positive Differential Analog
Input.
SCK (Pin 16): In serial programming mode, (PAR/SER =
0V), SCK is the serial interface clock input. In the parallel
programming mode (PAR/SER= VDD), SCK selects 3.5mA
or 1.75mA LVDS output currents. SCK can be driven with
1.8V to 3.3V logic.
SDI (Pin 17): In serial programming mode, (PAR/SER =
0V), SDI is the serial interface data input. Data on SDI is
clocked into the mode control registers on the rising edge
of SCK. In the parallel programming mode (PAR/SER =
VDD), SDI can be used to power down the part. SDI can
be driven with 1.8V to 3.3V logic.
GND (Pins 18, 33, 37, Exposed Pad Pin 41): ADC Power
Ground. The exposed pad must be soldered to the PCB
ground.
OGND (Pin 25): Output Driver Ground. Must be shorted
to the ground plane by a very low inductance path. Use
multiple vias close to the pin.
OVDD (Pin 26): Output Driver Supply, 1.7V to 1.9V. Bypass
to ground with a 0.1µF ceramic capacitor.
ENC– (Pin 14): Encode Complement Input. Conversion
starts on the falling edge.
SDO (Pin 34): In serial programming mode, (PAR/SER
= 0V), SDO is the optional serial interface data output.
Data on SDO is read back from the mode control registers
and can be latched on the falling edge of SCK. SDO is an
open-drain NMOS output that requires an external 2k
pull-up resistor to 1.8V – 3.3V. If read back from the mode
control registers is not needed, the pull-up resistor is not
necessary and SDO can be left unconnected. In the parallel
programming mode (PAR/SER = VDD), SDO is an input that
enables internal 100Ω termination resistors on the digital
outputs. When used as an input, SDO can be driven with
1.8V to 3.3V logic through a 1k series resistor.
CS (Pin 15): In serial programming mode, (PAR/SER=0V),
CS is the serial interface chip select input. When CS is low,
SCK is enabled for shifting data on SDI into the mode control
registers. In the parallel programming mode (PAR/SER =
VDD), CS selects 2-lane or 1-lane output mode. CS can
be driven with 1.8V to 3.3V logic.
PAR/SER (Pin 35): Programming Mode Selection Pin.
Connect to ground to enable the serial programming mode.
CS, SCK, SDI, SDO become a serial interface that control
the A/D operating modes. Connect to VDD to enable the
parallel programming mode where CS, SCK, SDI, SDO
become parallel logic inputs that control a reduced set of
AIN2– (Pin 10): Channel 2 Negative Differential Analog
Input.
VDD (Pins 11, 12, 39, 40): Analog Power Supply, 1.7V
to 1.9V. Bypass to ground with 0.1µF ceramic capacitors.
Adjacent pins can share a bypass capacitor.
ENC+ (Pin 13): Encode Input. Conversion starts on the
rising edge.
22687612fa
16
LTC2268-12/
LTC2267-12/LTC2266-12
Pin Functions
the A/D operating modes. PAR/SER should be connected
directly to ground or the VDD of the part and not be driven
by a logic signal.
VREF (Pin 36): Reference Voltage Output. Bypass to ground
with a 1µF ceramic capacitor, nominally 1.25V.
SENSE (Pin 38): Reference Programming Pin. Connecting
SENSE to VDD selects the internal reference and a ±1V input
range. Connecting SENSE to ground selects the internal
reference and a ±0.5V input range. An external reference
between 0.625V and 1.3V applied to SENSE selects an
input range of ±0.8 • VSENSE.
LVDS Outputs
All pins below are differential LVDS outputs. The output
current level is programmable. There is an optional
internal 100Ω termination resistor between the pins of
each LVDS output pair.
OUT2B – /OUT2B + , OUT2A – /OUT2A + (Pins 19/20,
Pins 21/22): Serial Data Outputs for Channel 2. In 1-lane
output mode only OUT2A–/OUT2A+ are used.
FR–/FR+ (Pins 23/24): Frame Start Outputs.
DCO–/DCO+ (Pins 27/28): Data Clock Outputs.
OUT1B – /OUT1B + , OUT1A – /OUT1A + (Pins 29/30,
Pins 31/32): Serial Data Outputs for Channel 1. In 1-lane
output mode only OUT1A–/OUT1A+ are used.
22687612fa
17
LTC2268-12/
LTC2267-12/LTC2266-12
Block Diagram
1.8V
1.8V
ENC+
VDD
ENC–
OVDD
OUT1A+
CHANNEL 1
ANALOG INPUT–
OUT1A–
PLL
CHANNEL 1
ANALOG INPUT+
OUT1B+
OUT1B–
12-BIT
ADC CORE
SAMPLEAND-HOLD
OUT2A+
CHANNEL 2
ANALOG INPUT+
CHANNEL 2
ANALOG INPUT–
OUT2A–
DATA
SERIALIZER
OUT2B+
12-BIT
ADC CORE
SAMPLEAND-HOLD
OUT2B–
DATA
CLOCK OUT+
VREF
1µF
DATA
CLOCK OUT–
1.25V
REFERENCE
FRAME+
RANGE
SELECT
FRAME–
REFH
REF
BUF
SENSE
OGND
REFL
VDD /2
DIFF
REF
AMP
GND
MODE
CONTROL
REGISTERS
REFH
REFL
VCM1
VCM2
PAR/SER
CS
SCK
SDI
SDO
226812 F01
0.1µF
0.1µF
0.1µF
2.2µF
0.1µF
0.1µF
Figure 1. Functional Block Diagram
22687612fa
18
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
CONVERTER OPERATION
ANALOG INPUT
The LTC2268-12/LTC2267-12/LTC2266-12 are low power,
2-channel, 12-bit, 125Msps/105Msps/80Msps A/D converters that are powered by a single 1.8V supply. The
analog inputs should be driven differentially. The encode
input can be driven differentially for optimal jitter performance, or single ended for lower power consumption.
To minimize the number of data lines the digital outputs
are serial LVDS. Each channel outputs two bits at a time
(2-lane mode). At lower sampling rates there is a one bit
per channel option (1-lane mode). Many additional features
can be chosen by programming the mode control registers
through a serial SPI port.
The analog inputs are differential CMOS sample-and-hold
circuits (Figure 2). The inputs should be driven differentially
around a common mode voltage set by the VCM1 or VCM2
output pins, which are nominally VDD/2. For the 2V input
range, the inputs should swing from VCM – 0.5V to VCM
+ 0.5V. There should be 180° phase difference between
the inputs.
The two channels are simultaneously sampled by a shared
encode circuit (Figure 2).
INPUT DRIVE CIRCUITS
Input filtering
LTC2268-12
VDD
+
AIN
RON
25Ω
10Ω
CPARASITIC
1.8pF
VDD
AIN–
CSAMPLE
3.5pF
RON
25Ω
10Ω
CSAMPLE
3.5pF
CPARASITIC
1.8pF
If possible, there should be an RC lowpass filter right at
the analog inputs. This lowpass filter isolates the drive
circuitry from the A/D sample-and-hold switching, and
also limits wideband noise from the drive circuitry. Figure 3
shows an example of an input RC filter. The RC component
values should be chosen based on the application’s input
frequency.
VDD
50Ω
VCM
0.1µF
0.1µF
1.2V
ANALOG
INPUT
10k
ENC+
T1
1:1
25Ω
25Ω
AIN+
LTC2268-12
0.1µF
12pF
25Ω
ENC–
10k
25Ω
T1: MA/COM MABAES0060
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
1.2V
AIN–
226812 F03
226812 F02
Figure 2. Equivalent Input Circuit. Only One
of the Two Analog Channels Is Shown
Figure 3. Analog Input Circuit Using a Transformer.
Recommended for Input Frequencies from 5MHz to 70MHz
22687612fa
19
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
Transformer Coupled Circuits
Amplifier Circuits
Figure 3 shows the analog input being driven by an RF
transformer with a center-tapped secondary. The center
tap is biased with VCM, setting the A/D input at its optimal
DC level. At higher input frequencies a transmission line
balun transformer (Figures 4 to 6) has better balance,
resulting in lower A/D distortion.
Figure 7 shows the analog input being driven by a high
speed differential amplifier. The output of the amplifier is
AC-coupled to the A/D so the amplifier’s output common
mode voltage can be optimally set to minimize distortion.
50Ω
VCM
0.1µF
0.1µF
ANALOG
INPUT
AIN+
T2
T1
25Ω
At very high frequencies an RF gain block will often
have lower distortion than a differential amplifier. If the
gain block is single-ended, then a transformer circuit
(Figures 4 to 6) should convert the signal to differential
before driving the A/D.
LTC2268-12
0.1µF
50Ω
4.7pF
0.1µF
25Ω
0.1µF
AIN–
0.1µF
226812 F04
2.7nH
ANALOG
INPUT
T1: MA/COM MABA-007159-000000
T2: MA/COM MABAES0060
RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE
AIN+
LTC2268-12
0.1µF
25Ω
T1
0.1µF
Figure 4.Recommended Front End Circuit for Input
Frequencies from 70MHz to 170MHz
50Ω
VCM
25Ω
2.7nH
AIN–
T1: MA/COM ETC1-1-13
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
226812 F06
Figure 6. Recommended Front End Circuit for Input
Frequencies Above 300MHz
VCM
0.1µF
0.1µF
ANALOG
INPUT
AIN+
T2
T1
25Ω
VCM
LTC2268-12
0.1µF
HIGH SPEED
DIFFERENTIAL
0.1µF
AMPLIFIER
1.8pF
0.1µF
25Ω
AIN–
ANALOG
INPUT
226812 F05
T1: MA/COM MABA-007159-000000
T2: COILCRAFT WBC1-1LB
RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE
Figure 5. Recommended Front End Circuit for Input
Frequencies from 170MHz to 300MHz
+
+
–
–
200Ω
200Ω
25Ω
0.1µF
AIN+
LTC2268-12
12pF
0.1µF
25Ω
AIN–
226812 F07
Figure 7. Front End Circuit Using a High Speed
Differential Amplifier
22687612fa
20
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
Reference
The LTC2268-12/LTC2267-12/LTC2266-12 has an internal
1.25V voltage reference. For a 2V input range using the
internal reference, connect SENSE to VDD. For a 1V input
range using the internal reference, connect SENSE to
ground. For a 2V input range with an external reference,
apply a 1.25V reference voltage to SENSE (Figure 9).
The input range can be adjusted by applying a voltage to
SENSE that is between 0.625V and 1.30V. The input range
will then be 1.6 • VSENSE.
LTC2268-12
VREF
1.25V
5Ω
1.25V BANDGAP
REFERENCE
1µF
0.625V
TIE TO VDD FOR 2V RANGE;
TIE TO GND FOR 1V RANGE;
RANGE = 1.6 • VSENSE FOR
0.625V < VSENSE < 1.300V
The VREF, REFH and REFL pins should be bypassed as
shown in Figure 8. The 0.1µF capacitor between REFH
and REFL should be as close to the pins as possible (not
on the backside of the circuit board).
Encode Input
The signal quality of the encode inputs strongly affects
the A/D noise performance. The encode inputs should be
treated as analog signals — do not route them next to
digital traces on the circuit board. There are two modes
of operation for the encode inputs: the differential encode
mode (Figure 10), and the single-ended encode mode
(Figure 11).
RANGE
DETECT
AND
CONTROL
LTC2268-12
VDD
SENSE
BUFFER
15k
REFH
ENC+
0.1µF
0.1µF
DIFFERENTIAL
COMPARATOR
VDD
INTERNAL ADC
HIGH REFERENCE
0.1µF
2.2µF
The reference is shared by both ADC channels, so it is
not possible to independently adjust the input range of
individual channels.
ENC–
0.8x
DIFF AMP
30k
REFL
226812 F10
INTERNAL ADC
LOW REFERENCE
Figure 10. Equivalent Encode Input Circuit
for Differential Encode Mode
226812 F08
Figure 8. Reference Circuit
LTC2268-12
1.8V TO 3.3V
VREF
1µF
1.25V
EXTERNAL
REFERENCE
0V
LTC2268-12
SENSE
ENC+
ENC–
30k
CMOS LOGIC
BUFFER
226812 F11
1µF
226812 F09
Figure 11. Equivalent Encode Input Circuit
for Single-Ended Encode Mode
Figure 9. Using an External 1.25V Reference
22687612fa
21
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
The differential encode mode is recommended for sinusoidal, PECL, or LVDS encode inputs (Figures 12 and 13).
The encode inputs are internally biased to 1.2V through
10k equivalent resistance. The encode inputs can be taken
above VDD (up to 3.6V), and the common mode range is
from 1.1V to 1.6V. In the differential encode mode, ENC–
should stay at least 200mV above ground to avoid falsely
triggering the single-ended encode mode. For good jitter
performance ENC+ should have fast rise and fall times.
The single-ended encode mode should be used with CMOS
encode inputs. To select this mode, ENC– is connected
to ground and ENC+ is driven with a square wave encode
input. ENC+ can be taken above VDD (up to 3.6V) so 1.8V
to 3.3V CMOS logic levels can be used. The ENC+ threshold
is 0.9V. For good jitter performance ENC+ should have fast
rise and fall times.
0.1µF
ENC+
T1
50Ω
0.1µF
LTC2268-12
100Ω
50Ω
ENC–
0.1µF
226812 F12
T1 = MA/COM ETC1-1-13
RESISTORS AND CAPACITORS
ARE 0402 PACKAGE SIZE
Figure 12. Sinusoidal Encode Drive
0.1µF
PECL OR
LVDS
CLOCK
Clock PLL and Duty Cycle Stabilizer
The encode clock is multiplied by an internal phase-locked
loop (PLL) to generate the serial digital output data. If the
encode signal changes frequency or is turned off, the PLL
requires 25µs to lock onto the input clock.
A clock duty cycle stabilizer circuit allows the duty cycle
of the applied encode signal to vary from 30% to 70%.
In the serial programming mode it is possible to disable
the duty cycle stabilizer, but this is not recommended. In
the parallel programming mode the duty cycle stabilizer
is always enabled.
DIGITAL OUTPUTS
The digital outputs of the LTC2268-12/LTC2267-12/
LTC2266-12 are serialized LVDS signals. Each channel
outputs two bits at a time (2-lane mode). At lower sampling rates there is a one bit per channel option (1-lane
mode). The data can be serialized with 16-, 14-, or 12-bit
serialization (see Timing Diagrams for details).
The output data should be latched on the rising and falling
edges of the data clock out (DCO). A data frame output
(FR) can be used to determine when the data from a new
conversion result begins. In the 2-lane, 14-bit serialization
mode, the frequency of the FR output is halved.
The maximum serial data rate for the data outputs is 1Gbps,
so the maximum sample rate of the ADC will depend on
the serialization mode as well as the speed grade of the
ADC (see Table 1). The minimum sample rate for all serialization modes is 5Msps.
ENC+
LTC2268-12
0.1µF
ENC
–
226812 F13
Figure 13. PECL or LVDS Encode Drive
22687612fa
22
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
Table 1. Maximum Sampling Frequency for All Serialization Modes. Note That These Limits Are for the LTC2268-12. The Sampling
Frequency for the Slower Speed Grades Cannot Exceed 105MHz (LTC2267-12) or 80MHz (LTC2266-12).
SERIALIZATION MODE
MAXIMUM SAMPLING
FREQUENCY, fS (MHz)
DCO FREQUENCY
FR FREQUENCY
SERIAL DATA RATE
2-Lane
16-Bit Serialization
125
4 • fS
fS
8 • fS
2-Lane
14-Bit Serialization
125
3.5 • fS
0.5 • fS
7 • fS
2-Lane
12-Bit Serialization
125
3 • fS
fS
6 • fS
1-Lane
16-Bit Serialization
62.5
8 • fS
fS
16 • fS
1-Lane
14-Bit Serialization
71.4
7 • fS
fS
14 • fS
1-Lane
12-Bit Serialization
83.3
6 • fS
fS
12 • fS
By default the outputs are standard LVDS levels: 3.5mA
output current and a 1.25V output common mode voltage. An external 100Ω differential termination resistor
is required for each LVDS output pair. The termination
resistors should be located as close as possible to the
LVDS receiver.
DATA FORMAT
The outputs are powered by OVDD and OGND which are
isolated from the A/D core power and ground.
In addition to the 12 data bits (D11 - D0), two additional
bits (DX and DY) are sent out in the 14-bit and 16-bit
serialization modes. These extra bits are to ensure complete software compatibility with the 14-bit versions of
these A/Ds. During normal operation when the analog
inputs are not overranged, DX and DY are always logic 0.
When the analog inputs are overranged positive, DX and
DY become logic 1. When the analog inputs are overranged
negative, DX and DY become logic 0. DX and DY can also
be controlled by the digital output test pattern. See the
Timing Diagrams section for more information.
Programmable LVDS Output Current
The default output driver current is 3.5mA. This current
can be adjusted by control register A2 in the serial programming mode. Available current levels are 1.75mA,
2.1mA, 2.5mA, 3mA, 3.5mA, 4mA and 4.5mA. In the
parallel programming mode the SCK pin can select either
3.5mA or 1.75mA.
Optional LVDS Driver Internal Termination
In most cases using just an external 100Ω termination
resistor will give excellent LVDS signal integrity. In addition, an optional internal 100Ω termination resistor can
be enabled by serially programming mode control register
A2. The internal termination helps absorb any reflections
caused by imperfect termination at the receiver. When the
internal termination is enabled, the output driver current is
doubled to maintain the same output voltage swing. In the
Parallel Programming Mode, the SDO pin enables internal
termination. Internal termination should only be used with
1.75mA, 2.1mA or 2.5mA LVDS output current modes.
Table 2 shows the relationship between the analog input
voltage and the digital data output bits. By default the
output data format is offset binary. The 2’s complement
format can be selected by serially programming mode
control register A1.
Table 2. Output Codes vs Input Voltage
AIN+ – AIN–
(2V RANGE)
>+1.000000V
D11-D0
(OFFSET BINARY)
1111 1111 1111
D11-D0
(2’s COMPLEMENT)
0111 1111 1111
DX, DY
11
+0.999512V
1111 1111 1111
0111 1111 1111
00
+0.999024V
1111 1111 1110
0111 1111 1110
00
+0.000488V
1000 0000 0001
0000 0000 0001
00
0.000000V
1000 0000 0000
0000 0000 0000
00
–0.000488V
0111 1111 1111
1111 1111 1111
00
–0.000976V
0111 1111 1110
1111 1111 1110
00
–0.999512V
0000 0000 0001
1000 0000 0001
00
–1.000000V
0000 0000 0000
1000 0000 0000
00
≤–1.000000V
0000 0000 0000
1000 0000 0000
00
22687612fa
23
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
Digital Output Randomizer
Interference from the A/D digital outputs is sometimes
unavoidable. Digital interference may be from capacitive or
inductive coupling or coupling through the ground plane.
Even a tiny coupling factor can cause unwanted tones
in the ADC output spectrum. By randomizing the digital
output before it is transmitted off chip, these unwanted
tones can be randomized which reduces the unwanted
tone amplitude.
The digital output is randomized by applying an exclusive-OR logic operation between the LSB and all other
data output bits. To decode, the reverse operation is
applied—an exclusive-OR operation is applied between
the LSB and all other bits. The FR and DCO outputs are
not affected. The output randomizer is enabled by serially
programming mode control register A1.
Digital Output Test Pattern
To allow in-circuit testing of the digital interface to the
A/D, there is a test mode that forces the A/D data outputs
(D11-D0, DX, DY) of both channels to known values. The
digital output test patterns are enabled by serially programming mode control registers A3 and A4. When enabled,
the test patterns override all other formatting modes: 2’s
complement and randomizer.
Output Disable
The digital outputs may be disabled by serially programming mode control register A2. The current drive for all
digital outputs including DCO and FR are disabled to save
power or enable in-circuit testing. When disabled the common mode of each output pair becomes high impedance,
but the differential impedance may remain low.
In nap mode any combination of A/D channels can be
powered down while the internal reference circuits and the
PLL stay active, allowing faster wake-up than from sleep
mode. Recovering from nap mode requires at least 100
clock cycles. If the application demands very accurate DC
settling then an additional 50µs should be allowed so the
on-chip references can settle from the slight temperature
shift caused by the change in supply current as the A/D
leaves nap mode. Nap mode is enabled by mode control
register A1 in the serial programming mode.
DEVICE PROGRAMMING MODES
The operating modes of the LTC2268-12/LTC2267-12/
LTC2266-12 can be programmed by either a parallel
interface or a simple serial interface. The serial interface
has more flexibility and can program all available modes.
The parallel interface is more limited and can only program
some of the more commonly used modes.
Parallel Programming Mode
To use the parallel programming mode, PAR/SER should
be tied to VDD. The CS, SCK, SDI and SDO pins are binary
logic inputs that set certain operating modes. These pins
can be tied to VDD or ground, or driven by 1.8V, 2.5V, or
3.3V CMOS logic. When used as an input, SDO should
be driven through a 1k series resistor. Table 3 shows the
modes set by CS, SCK, SDI and SDO.
Table 3. Parallel Programming Mode Control Bits (PAR/SER = VDD)
PIN
DESCRIPTION
CS
2-Lane/1-Lane Selection Bit
0 = 2-Lane, 16-Bit Serialization Output Mode
1 = 1-Lane, 14-Bit Serialization Output Mode
SCK
LVDS Current Selection Bit
Sleep and Nap Modes
0 = 3.5mA LVDS Current Mode
The A/D may be placed in sleep or nap modes to conserve
power. In sleep mode the entire device is powered down,
resulting in 1mW power consumption. Sleep mode is
enabled by mode control register A1 (serial programming mode), or by SDI (parallel programming mode).
The amount of time required to recover from sleep mode
depends on the size of the bypass capacitors on VREF,
REFH, and REFL. For the suggested values in Figure 8,
the A/D will stabilize after 2ms.
1 = 1.75mA LVDS Current Mode
24
SDI
Power Down Control Bit
0 = Normal Operation
1 = Sleep Mode
SDO
Internal 100Ω Termination Selection Bit
0 = Internal Termination Disabled
1 = Internal Termination Enabled
22687612fa
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
Serial Programming Mode
To use the serial programming mode, PAR/SER should be
tied to ground. The CS, SCK, SDI and SDO pins become
a serial interface that programs the A/D mode control
registers. Data is written to a register with a 16-bit serial
word. Data can also be read back from a register to verify
its contents.
Serial data transfer starts when CS is taken low. The data
on the SDI pin is latched at the first 16 rising edges of
SCK. Any SCK rising edges after the first 16 are ignored.
The data transfer ends when CS is taken high again.
The first bit of the 16-bit input word is the R/W bit. The
next seven bits are the address of the register (A6:A0).
The final eight bits are the register data (D7:D0).
If the R/W bit is low, the serial data (D7:D0) will be written
to the register set by the address bits (A6:A0). If the R/W bit
is high, data in the register set by the address bits (A6:A0)
will be read back on the SDO pin (see the Timing Diagrams
section). During a read back command the register is not
updated and data on SDI is ignored.
The SDO pin is an open-drain output that pulls to ground
with a 200Ω impedance. If register data is read back
through SDO, an external 2k pull-up resistor is required. If
serial data is only written and read back is not needed, then
SDO can be left floating and no pull-up resistor is needed.
Table 4 shows a map of the mode control registers.
Software Reset
If serial programming is used, the mode control registers
should be programmed as soon as possible after the power
supplies turn on and are stable. The first serial command
must be a software reset which will reset all register data bits
to logic 0. To perform a software reset, bit D7 in the reset
register is written with a logic 1. After the reset SPI write
command is complete, bit D7 is automatically set back to zero.
Table 4. Serial Programming Mode Register Map (PAR/SER = GND)
REGISTER A0: RESET REGISTER (ADDRESS 00h)
D7
D6
RESET
X
RESET
Bit 7
D5
D4
D3
D2
D1
D0
X
X
X
X
X
X
Software Reset Bit
0 = Not Used
1 = Software Reset. All Mode Control Registers Are Reset to 00h. The ADC is momentarily placed in SLEEP mode.
This Bit Is Automatically Set Back to Zero at the End of the SPI Write Command.
The Reset Register is Write Only.
Bits 6-0
Unused, Don’t Care Bits.
REGISTER A1: POWER-DOWN REGISTER (ADDRESS 01h)
D7
D6
D5
D4
D3
D2
D1
D0
DCSOFF
RAND
TWOSCOMP
SLEEP
NAP_2
X
X
NAP_1
Bit 7
DCSOFF
Clock Duty Cycle Stabilizer Bit
0 = Clock Duty Cycle Stabilizer On
1 = Clock Duty Cycle Stabilizer Off. This is Not Recommended.
Bit 6
RAND
Data Output Randomizer Mode Control Bit
0 = Data Output Randomizer Mode Off
1 = Data Output Randomizer Mode On
Bit 5
TWOSCOMP Two’s Complement Mode Control Bit
0 = Offset Binary Data Format
1 = Two’s Complement Data Format
Bits 4,3,0
Sleep/Nap Mode Control Bits
SLEEP:NAP_2:NAP_1
000 = Normal Operation
0X1 = Channel 1 in Nap Mode
01X = Channel 2 in Nap Mode
1XX = Sleep Mode. Both Channels Are Disabled
Note: Any Combination of Channels Can Be Placed in Nap Mode.
Bits 2,1
Unused, Don’t Care Bits.
22687612fa
25
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
REGISTER A2: OUTPUT MODE REGISTER (ADDRESS 02h)
D7
ILVDS2
D6
D5
D4
D3
D2
D1
D0
ILVDS1
ILVDS0
TERMON
OUTOFF
OUTMODE2
OUTMODE1
OUTMODE0
Bits 7-5
ILVDS2:ILVDS0 LVDS Output Current Bits
000 = 3.5mA LVDS Output Driver Current
001 = 4.0mA LVDS Output Driver Current
010 = 4.5mA LVDS Output Driver Current
011 = Not Used
100 = 3.0mA LVDS Output Driver Current
101 = 2.5mA LVDS Output Driver Current
110 = 2.1mA LVDS Output Driver Current
111 = 1.75mA LVDS Output Driver Current
Bit 4
LVDS Internal Termination Bit
TERMON
0 = Internal Termination Off
1 = Internal Termination On. LVDS Output Driver Current is 2x the Current Set by ILVDS2:ILVDS0. Internal termination should only be
used with 1.75mA, 2.1mA or 2.5mA LVDS output current modes.
Bit 3
OUTOFF
Output Disable Bit
0 = Digital Outputs are enabled.
1 = Digital Outputs are disabled.
Bits 2-0
OUTMODE2:OUTMODE0 Digital Output Mode Control Bits
000 = 2-Lanes, 16-Bit Serialization
001 = 2-Lanes, 14-Bit Serialization
010 = 2-Lanes, 12-Bit Serialization
011 = Not Used
100 = Not Used
101 = 1-Lane, 14-Bit Serialization
110 = 1-Lane, 12-Bit Serialization
111 = 1-Lane, 16-Bit Serialization
REGISTER A3: TEST PATTERN MSB REGISTER (ADDRESS 03h)
D7
OUTTEST
D6
D5
D4
D3
D2
D1
D0
X
TP11
TP10
TP9
TP8
TP7
TP6
Bit 7
OUTTEST
Digital Output Test Pattern Control Bit
0 = Digital Output Test Pattern Off
1 = Digital Output Test Pattern On
Bit 6
Unused, Don’t Care Bit.
Bits 5-0
TP11:TP6
Test Pattern Data Bits (MSB)
TP11:TP6 Set the Test Pattern for Data Bit 11 (MSB) Through Data Bit 6.
REGISTER A4: TEST PATTERN LSB REGISTER (ADDRESS 04h)
D7
D6
D5
D4
D3
D2
D1
D0
TP5
TP4
TP3
TP2
TP1
TP0
TPX
TPY
Bits 7-2
TP5:TP0
Test Pattern Data Bits (LSB)
TP5:TP0 Set the Test Pattern for Data Bit 5 Through Data Bit 0 (LSB).
Bits 1-0
TPX:TPY
Set the Test Pattern for Extra Bits DX and DY. These Bits are for Compatibility with the 14-Bit Version of the A/D.
22687612fa
26
LTC2268-12/
LTC2267-12/LTC2266-12
Applications Information
GROUNDING AND BYPASSING
The LTC2268-12/LTC2267-12/LTC2266-12 requires a
printed circuit board with a clean unbroken ground plane.
A multilayer board with an internal ground plane in the
first layer beneath the ADC is recommended. Layout for
the printed circuit board should ensure that digital and
analog signal lines are separated as much as possible. In
particular, care should be taken not to run any digital track
alongside an analog signal track or underneath the ADC.
High quality ceramic bypass capacitors should be used at
the VDD, OVDD, VCM, VREF, REFH and REFL pins. Bypass
capacitors must be located as close to the pins as possible.
Of particular importance is the 0.1µF capacitor between
REFH and REFL. This capacitor should be on the same
side of the circuit board as the A/D, and as close to the
device as possible (1.5mm or less). Size 0402 ceramic
capacitors are recommended. The larger 2.2µF capacitor
between REFH and REFL can be somewhat further away.
The traces connecting the pins and bypass capacitors must
be kept short and should be made as wide as possible.
The analog inputs, encode signals, and digital outputs
should not be routed next to each other. Ground fill and
grounded vias should be used as barriers to isolate these
signals from each other.
HEAT TRANSFER
Most of the heat generated by the LTC2268-12/LTC2267‑12/
LTC2266-12 is transferred from the die through the
bottom-side Exposed Pad and package leads onto the
printed circuit board. For good electrical and thermal
performance, the Exposed Pad must be soldered to a large
grounded pad on the PC board. This pad should be connected to the internal ground planes by an array of vias.
TYPICAL APPLICATIONS
Silkscreen Top
Top Side
22687612fa
27
LTC2268-12/
LTC2267-12/LTC2266-12
TYPICAL APPLICATIONS
Inner Layer 2 GND
Inner Layer 3
Inner Layer 4
Inner Layer 5 Power
Bottom Side
Silkscreen Bottom
22687612fa
28
LTC2268-12/
LTC2267-12/LTC2266-12
TYPICAL APPLICATIONS
LTC2268 Schematic
PAR/SER
C4
1µF
SDO
SENSE
VDD
C5
1µF
C59
0.1µF
9
10
OUT1A–
GND
OUT1A+
SDO
VREF
PAR/SER
GND
28
REFH
DCO–
27
LTC2268
REFH
OVDD
26
25
REFL
OGND
REFL
FR+
VCM2
FR–
AIN2+
OUT2A+
22
AIN2–
OUT2A–
21
VDD
AIN2
AIN2
OUT2B+
8
DCO+
OUT2B–
7
VCM1
GND
6
29
SDI
C3
0.1µF
C30
0.1µF
OUT1B–
SCK
C2
0.1µF
C1
2.2µF
5
AIN1–
CS
4
30
ENC–
3
DIGITAL
OUTPUTS
OUT1B+
AIN1+
ENC+
2
VDD
1
VDD
VDD
C29
0.1µF
AIN1
SENSE
40 39 38 37 36 35 34 33 32 31
AIN1
24
OVDD
23
DIGITAL
OUTPUTS
11 12 13 14 15 16 17 18 19 20
VDD
C16
0.1µF
C7
0.1µF
C47
0.1µF
ENCODE
CLOCK
C46
0.1µF
ENCODE
CLOCK
SPI BUS
226812 TA02
22687612fa
29
LTC2268-12/
LTC2267-12/LTC2266-12
Package Description
UJ Package
40-Lead Plastic QFN (6mm × 6mm)
(Reference LTC DWG # 05-08-1728 Rev Ø)
0.70 0.05
6.50 0.05
5.10 0.05
4.42 0.05
4.50 0.05
(4 SIDES)
4.42 0.05
PACKAGE OUTLINE
0.25 0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
6.00 0.10
(4 SIDES)
0.75 0.05
R = 0.10
TYP
R = 0.115
TYP
39 40
0.40 0.10
PIN 1 TOP MARK
(SEE NOTE 6)
1
4.50 REF
(4-SIDES)
4.42 0.10
2
PIN 1 NOTCH
R = 0.45 OR
0.35 ¥ 45
CHAMFER
4.42 0.10
(UJ40) QFN REV Ø 0406
0.200 REF
0.00 – 0.05
NOTE:
1. DRAWING IS A JEDEC PACKAGE OUTLINE VARIATION OF (WJJD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.25 0.05
0.50 BSC
BOTTOM VIEW—EXPOSED PAD
22687612fa
30
LTC2268-12/
LTC2267-12/LTC2266-12
Revision History
REV
DATE
DESCRIPTION
A
6/11
Revised Software Reset paragraph and Table 4 in Applications Information section
PAGE NUMBER
25
22687612fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
31
LTC2268-12/
LTC2267-12/LTC2266-12
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
ADCs
LTC2170-14/LTC2171-14/ 14-Bit, 25Msps/40Msps/65Msps 1.8V
LTC2172-14
Quad ADCs, Ultralow Power
178mW/234mW/360mW, 73.4dB SNR, 88dB SFDR, Serial LVDS Outputs,
7mm × 8mm QFN-52
LTC2170-12/LTC2171-12/ 12-Bit, 25Msps/40Msps/65Msps 1.8V
LTC2172-12
Quad ADCs, Ultralow Power
178mW/234mW/360mW, 70.5dB SNR, 88dB SFDR, Serial LVDS Outputs,
7mm × 8mm QFN-52
LTC2173-14/LTC2174-14/ 14-Bit, 80Msps/105Msps/125Msps
LTC2175-14
1.8V Quad ADCs, Ultralow Power
373mW/445mW/551mW, 73.2 dB SNR, 88dB SFDR, Serial LVDS Outputs,
7mm × 8mm QFN-52
LTC2173-12/LTC2174-12/ 12-Bit, 80Msps/105Msps/125Msps 1.8V
LTC2175-12
Quad ADCs, Ultralow Power
412mW/481mW/567mW, 70.5 dB SNR, 88dB SFDR, Serial LVDS Outputs,
7mm × 8mm QFN-52
LTC2256-14/LTC2257-14/ 14-Bit, 25Msps/40Msps/65Msps 1.8V
LTC2258-14
ADCs, Ultralow Power
35mW/49mW/81mW, 74dB SNR, 88dB SFDR, DDR LVDS/DDR CMOS/CMOS
Outputs, 6mm × 6mm QFN-36
LTC2259-14/LTC2260-14/ 14-Bit, 80Msps/105Msps/125Msps 1.8V
LTC2261-14
ADCs, Ultralow Power
89mW/106mW/127mW, 73.4dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/CMOS
Outputs, 6mm × 6mm QFN-36
LTC2262-14
14-Bit, 150Msps 1.8V ADC, Ultralow Power 149mW, 72.8dB SNR, 88dB SFDR, DDR LVDS/DDR CMOS/CMOS Outputs,
6mm × 6mm QFN-36
LTC2263-14/LTC2264-14/ 14-Bit, 25Msps/40Msps/65Msps 1.8V
LTC2265-14
Dual ADCs, Ultralow Power
99mW/126mW/191mW, 73.4dB SNR, 88dB SFDR, Serial LVDS Outputs,
6mm × 6mm QFN-36
LTC2263-12/LTC2264-12/ 12-Bit, 25Msps/40Msps/65Msps 1.8V
LTC2265-12
Dual ADCs, Ultralow Power
99mW/126mW/191mW, 70.5dB SNR, 88dB SFDR, Serial LVDS Outputs,
6mm × 6mm QFN-36
LTC2266-14/LTC2267-14/ 14-Bit, 80Msps/105Msps/125Msps
LTC2268-14
1.8V Dual ADCs, Ultralow Power
216mW/250mW/293mW, 73.4dB SNR, 88dB SFDR, Serial LVDS Outputs,
6mm × 6mm QFN-36
RF Mixers/Demodulators
LT5517
40MHz to 900MHz Direct Conversion
Quadrature Demodulator
High IIP3: 21dBm at 800MHz, Integrated LO Quadrature Generator
LT5527
400MHz to 3.7GHz High Linearity
Downconverting Mixer
24.5dBm IIP3 at 900MHz, 23.5dBm IIP3 at 3.5GHz, NF = 12.5dB,
50Ω Single-Ended RF and LO Ports
LT5557
400MHz to 3.8GHz High Linearity
Downconverting Mixer
23.7dBm IIP3 at 2.6GHz, 23.5dBm IIP3 at 3.5GHz, NF = 13.2dB, 3.3V Supply
Operation, Integrated Transformer
LT5575
800MHz to 2.7GHz Direct Conversion
Quadrature Demodulator
High IIP3: 28dBm at 900MHz, Integrated LO Quadrature Generator, Integrated RF
and LO Transformer
LTC6412
800MHz, 31dB Range, Analog-Controlled
Variable Gain Amplifier
Continuously Adjustable Gain Control, 35dBm OIP3 at 240MHz, 10dB Noise
Figure, 4mm × 4mm QFN-24
LTC6420-20
1.8GHz Dual Low Noise, Low Distortion
Differential ADC Drivers for 300MHz IF
Fixed Gain 10V/V, 1nV/√Hz Total Input Noise, 80mA Supply Current per Amplifier,
3mm × 4mm QFN-20
LTC6421-20
1.3GHz Dual Low Noise, Low Distortion
Differential ADC Drivers
Fixed Gain 10V/V, 1nV/√Hz Total Input Noise, 40mA Supply Current per Amplifier,
3mm × 4mm QFN-20
LTC6605-7/ LTC6605-10/
LTC6605-14
Dual Matched 7MHz/10MHz/14MHz Filters Dual Matched 2nd Order Lowpass Filters with Differential Drivers,
with ADC Drivers
Pin-Programmable Gain, 6mm × 3mm DFN-22
LTM9002
14-Bit Dual Channel IF/Baseband Receiver Integrated High Speed ADC, Passive Filters and Fixed Gain Differential Amplifiers
Subsystem
Amplifiers/Filters
22687612fa
32 Linear Technology Corporation
LT 0611 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
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