ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
14 Bit, 80 MSPS
Analog-to-Digital Converter
D 52 Pin HTQFP Package With Exposed
FEATURES
D 14 Bit Resolution
D 80 MSPS Maximum Sample Rate
D SNR = 74 dBc at 80 MSPS and 50 MHz IF
D SFDR = 94 dBc at 80 MSPS and 50 MHz IF
D 2.2 Vpp Differential Input Range
D 5 V Supply Operation
D 3.3 V CMOS Compatible Outputs
D 1.85 W Total Power Dissipation
D 2s Complement Output Format
D On-Chip Input Analog Buffer, Track and Hold,
Heatsink
D Pin Compatible to the AD6644/45
D Industrial Temperature Range = −405C to 855C
APPLICATIONS
D Single and Multichannel Digital Receivers
D Base Station Infrastructure
D Instrumentation
D Video and Imaging
RELATED DEVICES
D Clocking: CDC7005
D Amplifiers: OPA695, THS4509
and Reference Circuit
DESCRIPTION
The ADS5423 is a 14 bit 80 MSPS analog-to-digital converter (ADC) that operates from a 5 V supply, while providing 3.3 V
CMOS compatible digital outputs. The ADS5423 input buffer isolates the internal switching of the on-chip Track and Hold
(T&H) from disturbing the signal source. An internal reference generator is also provided to further simplify the system
design. The ADS5423 has outstanding low noise and linearity, over input frequency. With only a 2.2 VPP input range,
simplifies the design of multicarrier applications, where the carriers are selected on the digital domain.
The ADS5423 is available in a 52 pin HTQFP with heatsink package and is pin compatible to the AD6645. The ADS5423
is built on state of the art Texas Instruments complementary bipolar process (BiCom3) and is specified over full industrial
temperature range (−40°C to 85°C).
FUNCTIONAL BLOCK DIAGRAM
AVDD
AIN
AIN
TH1
A1
+
TH2
Σ
A2
+
TH3
ADC1
DAC1
A3
ADC3
−
−
VREF
Σ
DRVDD
ADC2
DAC2
Reference
5
5
6
C1
C2
CLK+
CLK−
Digital Error Correction
Timing
DMID OVR
DRY
D[13:0]
GND
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPad is a trademark of Texas Instruments. All other trademarks are the property of their respective owners.
Copyright 2005, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
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ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
This integrated circuit can be damaged by ESD. Texas
Instruments recommends that all integrated circuits be
handled with appropriate precautions. Failure to observe
proper handling and installation procedures can cause damage.
NOTE:
For the most current package and ordering
information, see the Package Option Addendum at
the end of this document, or see the TI Web site at
www.ti.com.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
ADS5423
Supply voltage
AVDD to GND
6
DRVDD to GND
5
ESD damage can range from subtle performance degradation to
complete device failure. Precision integrated circuits may be more
susceptible to damage because small parametric changes could cause
the device not to meet its published specifications.
UNIT
V
RECOMMENDED OPERATING CONDITIONS
PARAMETER
MIN
TYP
MAX
UNIT
4.75
5
5.25
V
3
3.3
3.6
V
Analog input to GND
−0.3 to
AVDD + 0.3
V
Clock input to GND
−0.3 to
AVDD + 0.3
V
±2.5
V
−0.3 to
DRVDD + 0.3
V
Differential input range
2.2
VPP
−40 to 85
°C
2.4
V
150
°C
Input common-mode voltage,
VCM
−65 to 150
°C
10
pF
CLK to CLK
Digital data output to GND
Operating temperature range
Maximum junction temperature
Storage temperature range
(1)
Analog supply voltage, AVDD
THERMAL CHARACTERISTICS(1)
(1)
2
Output driver supply voltage,
DRVDD
Analog Input
Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods
may degrade device reliability. These are stress ratings only, and
functional operation of the device at these or any other conditions
beyond those specified is not implied.
Digital Output
Maximum output load
Clock Input
ADCLK input sample rate (sine
wave) 1/tC
30
Clock amplitude, sine wave,
differential(1)
TYP
θJA
Soldered slug, no
airflow
22.5
°C/W
θJA
Soldered slug,
200-LPFM airflow
15.8
°C/W
θJA
Unsoldered slug,
no airflow
33.3
°C/W
θJA
Unsoldered slug,
200-LPFM airflow
25.9
°C/W
θJC
Bottom of
package
(heatslug)
2
°C/W
UNIT
Using 25 thermal vias (5 x 5 array). See the Application Section.
Open free-air temperature range
(1)
80
3
Clock duty cycle(2)
TEST
CONDITIONS
PARAMETER
Supplies
MSPS
VPP
50%
−40
85
See Figure 17 and Figure 18 for more information.
(2) See Figure 16 for more information.
°C
ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
ELECTRICAL CHARACTERISTICS
Over full temperature range (TMIN = −40°C to TMAX = 85°C), sampling rate = 80 MSPS, 50% clock duty cycle, AVDD = 5 V, DRVDD = 3.3 V,
−1 dBFS differential input, and 3 VPP differential sinusoidal clock, unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
Resolution
TYP
MAX
UNIT
14
Bits
2.2
VPP
1
kΩ
Analog Inputs
Differential input range
Differential input resistance
See Figure 30
Differential input capacitance
See Figure 30
Analog input bandwidth
1.5
pF
570
MHz
2.4
V
Internal Reference Voltages
Reference voltage, VREF
Dynamic Accuracy
No missing codes
Tested
Differential linearity error, DNL
fIN = 5 MHz
Integral linearity error, INL
fIN = 5 MHz
Offset error
−0.95
±0.5
1.5
±1.5
−5
Offset temperature coefficient
0
LSB
5
1.7
Gain error
−5
0.9
LSB
mV
ppm/°C
5
%FS
PSRR
1
mV/V
Gain temperature coefficient
77
ppm/°C
Power Supply
Analog supply current, IAVDD
VIN = full scale, fIN = 70 MHz
355
410
mA
Output buffer supply current, IDRVDD
VIN = full scale, fIN = 70 MHz
35
42
mA
Power dissipation
Total power with 10-pF load on each digital output
to ground, fIN = 70 MHz
1.85
2.2
W
20
100
ms
Power-up time
Dynamic AC Characteristics
fIN = 10 MHz
fIN = 30 MHz
74.6
73
fIN = 50 MHz
Signal-to-noise ratio, SNR
fIN = 70 MHz
74.2
73
fIN = 100 MHz
74.1
fIN = 170 MHz
72
fIN = 230 MHz
71.5
fIN = 30 MHz
dBc
73.5
fIN = 10 MHz
Spurious-free dynamic range, SFDR
74.3
94
85
93
fIN = 50 MHz
94
fIN = 70 MHz
90
fIN = 100 MHz
86
fIN = 170 MHz
73
fIN = 230 MHz
64
dBc
3
ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
ELECTRICAL CHARACTERISTICS
Over full temperature range (TMIN = −40°C to TMAX = 85°C), sampling rate = 80 MSPS, 50% clock duty cycle, AVDD = 5 V, DRVDD = 3.3 V,
−1 dBFS differential input, and 3 VPP differential sinusoidal clock, unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
fIN = 10 MHz
Second harmonic, HD2
Third harmonic, HD3
Worst-harmonic / spur (other than HD2 and
HD3)
RMS idle channel noise
MAX
UNIT
74.6
fIN = 30 MHz
Signal-to-noise + distortion, SINAD
TYP
72.8
74.2
fIN = 50 MHz
74.1
fIN = 70 MHz
73.9
fIN = 100 MHz
72.7
fIN = 170 MHz
69.1
fIN = 230 MHz
62.8
fIN = 10 MHz
105
fIN = 30 MHz
100
fIN = 50 MHz
99
fIN = 70 MHz
92
fIN = 100 MHz
90
fIN = 170 MHz
94
fIN = 230 MHz
88
fIN = 10 MHz
94
fIN = 30 MHz
93
fIN = 50 MHz
94
fIN = 70 MHz
90
fIN = 100 MHz
86
fIN = 170 MHz
73
fIN = 230 MHz
64
fIN = 10 MHz
94
fIN = 30 MHz
95
fIN = 50 MHz
95
fIN = 70 MHz
90
fIN = 100 MHz
88
fIN = 170 MHz
88
fIN = 230 MHz
88
Input pins tied together
0.9
dBc
dBc
dBc
dBc
LSB
DIGITAL CHARACTERISTICS
Over full temperature range (TMIN = −40°C to TMAX = 85°C), AVDD = 5 V, DRVDD = 3.3 V, unless otherwise noted
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
0.1
0.6
V
Digital Outputs
Low-level output voltage
CLOAD = 10 pF(1)
High-level output voltage
CLOAD = 10 pF(1)
Output capacitance
DMID
(1)
4
Equivalent capacitance to ground of (load + parasitics of transmission lines).
2.6
3.2
V
3
pF
DRVDD/2
V
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TIMING CHARACTERISTICS(3)
Over full temperature range, AVDD = 5 V, DRVDD = 3.3 V, sampling rate = 80 MSPS
DESCRIPTION
PARAMETER
MIN
TYP
MAX
UNIT
Aperture Time
tA
Aperture delay
500
tJ
Clock slope independent aperture uncertainity (jitter)
150
ps
fs
kJ
Clock slope dependent jitter factor
50
µV
Clock Input
tCLK
Clock period
12.5
ns
tCLKH(1)
Clock pulsewidth high
6.25
ns
tCLKL(1)
Clock pulsewidth low
6.25
ns
Clock to DataReady (DRY)
tDR
Clock rising 50% to DRY falling 50%
2.8
3.9
4.7
tDR +
tCLKH
tC_DR
Clock rising 50% to DRY rising 50%
tC_DR_50%
Clock rising 50% to DRY rising 50% with 50% duty cycle clock
9
10.1
ns
ns
11
ns
Clock to DATA, OVR(4)
tr
Data VOL to data VOH (rise time)
2
tf
Data VOH to data VOL (fall time)
2
ns
L
Latency
3
Cycles
tsu(C)
Valid DATA(2) to clock 50% with 50% duty cycle clock (setup time)
4.8
6.3
ns
2.6
3.6
ns
tH(C)
Clock 50% to invalid
DATA(2)
(hold time)
ns
DataReady (DRY) to DATA, OVR(4)
tsu(DR)_50%
Valid DATA(2) to DRY 50% with 50% duty cycle clock (setup time)
3.3
4
ns
th(DR)_50%
DRY 50% to invalid DATA(2) with 50% duty cycle clock (hold time)
5.4
5.9
ns
(1)
See Figure 1 for more information.
(2) See V
OH and VOL levels.
(3) All values obtained from design and characterization.
(4) Data is updated with clock rising edge or DRY falling edge.
tA
N+3
N
AIN
N+1
N+2
tCLKH
tCLK
CLK, CLK
N+1
N
N+4
tCLKL
N+2
N+3
tC_DR
D[13:0], OVR
DRY
N−3
tr
N−2
tf
tsu(C)
N−1
tsu(DR)
N+4
th(C)
N
th(DR)
tDR
Figure 1. Timing Diagram
5
ADS5423
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PIN CONFIGURATION
DRY
D13 (MSB)
D12
D11
D10
D9
D8
D7
D6
DRVCC
GND
D5
D4
PJY PACKAGE
(TOP VIEW)
52 51 50 49 48 47 46 45 44 43 42 41 40
DRVDD
GND
VREF
GND
CLK
CLK
GND
AVDD
AVDD
GND
AIN
AIN
GND
1
39
2
3
38
37
4
36
5
6
35
34
7
33
GND
8
9
32
31
10
30
11
12
29
28
13
27
D3
D2
D1
D0 (LSB)
DMID
GND
DRVDD
OVR
DNC
AVDD
GND
AVDD
GND
AVDD
GND
AVDD
GND
AVDD
GND
C1
GND
AVDD
GND
C2
GND
AVDD
14 15 16 17 18 19 20 21 22 23 24 25 26
PIN ASSIGNMENTS
TERMINAL
NAME
NO.
DRVDD
1, 33, 43
DESCRIPTION
3.3 V power supply, digital output stage only
GND
2, 4, 7, 10, 13, 15,
17, 19, 21, 23, 25,
27, 29, 34, 42
Ground
VREF
3
2.4 V reference. Bypass to ground with a 0.1-µF microwave chip capacitor.
CLK
5
Clock input. Conversion initiated on rising edge.
CLK
6
Complement of CLK, differential input
AVDD
8, 9, 14, 16, 18,
22, 26, 28, 30
5 V analog power supply
AIN
11
Analog input
AIN
12
Complement of AIN, differential analog input
C1
20
Internal voltage reference. Bypass to ground with a 0.1-µF chip capacitor.
C2
24
Internal voltage reference. Bypass to ground with a 0.1-µF chip capacitor.
DNC
31
Do not connect
OVR
32
Overrange bit. A logic level high indicates the analog input exceeds full scale.
DMID
35
Output data voltage midpoint. Approximately equal to (DVCC)/2
36
Digital output bit (least significant bit); two’s complement
D0 (LSB)
D1−D5, D6−D12
37−41, 44−50
Digital output bits in two’s complement
D13 (MSB)
51
Digital output bit (most significant bit); two’s complement
DRY
52
Data ready output
6
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DEFINITION OF SPECIFICATIONS
Analog Bandwidth
The analog input frequency at which the power of the
fundamental is reduced by 3 dB with respect to the low
frequency value.
Aperture Delay
The delay in time between the rising edge of the input
sampling clock and the actual time at which the
sampling occurs.
Aperture Uncertainty (Jitter)
The sample-to-sample variation in aperture delay.
Clock Pulse Width/Duty Cycle
The duty cycle of a clock signal is the ratio of the time
the clock signal remains at a logic high (clock pulse
width) to the period of the clock signal. Duty cycle is
typically expressed as a percentage. A perfect
differential sine wave clock results in a 50% duty cycle.
Maximum Conversion Rate
The maximum sampling rate at which certified
operation is given. All parametric testing is performed
at this sampling rate unless otherwise noted.
Minimum Conversion Rate
The minimum sampling rate at which the ADC
functions.
Differential Nonlinearity (DNL)
An ideal ADC exhibits code transitions at analog input
values spaced exactly 1 LSB apart. The DNL is the
deviation of any single step from this ideal value,
measured in units of LSB.
Integral Nonlinearity (INL)
The INL is the deviation of the ADC’s transfer function
from a best fit line determined by a least squares curve
fit of that transfer function, measured in units of LSB.
Gain Error
The gain error is the deviation of the ADC’s actual input
full-scale range from its ideal value. The gain error is
given as a percentage of the ideal input full-scale range.
Temperature Drift
The temperature drift coefficient (with respect to gain
error and offset error) specifies the change per degree
celcius of the paramter from TMIN or TMAX. It is
computed as the maximum variation of that parameter
over the whole temperature range divided by TMAX −
TMIN.
Signal-to-Noise Ratio (SNR)
SNR is the ratio of the power of the fundamental (PS)
to the noise floor power (PN), excluding the power at dc
and the first five harmonics.
SNR + 10Log 10
PS
PN
SNR is either given in units of dBc (dB to carrier) when
the absolute power of the fundamental is used as the
reference or dBFS (dB to full scale) when the power of
the fundamental is extrapolated to the converter’s
full-scale range.
Signal-to-Noise and Distortion (SINAD)
SINAD is the ratio of the power of the fundamental (PS)
to the power of all the other spectral components
including noise (PN) and distortion (PD), but excluding
dc.
SINAD + 10Log 10
PS
PN ) PD
SINAD is either given in units of dBc (dB to carrier) when
the absolute power of the fundamental is used as the
reference or dBFS (dB to full scale) when the power of
the fundamental is extrapolated to the converter’s
full-scale range.
Total Harmonic Distortion (THD)
THD is the ratio of the fundamental power (PS) to the
power of the first five harmonics (PD).
THD + 10Log 10
PS
PD
THD is typically given in units of dBc (dB to carrier).
Offset Error
The offset error is the difference, given in number of
LSBs, between the ADC’s actual value average idle
channel output code and the ideal average idle channel
output code. This quantity is often mapped into mV.
Power Up Time
The difference in time from the point where the supplies
are stable at ±5% of the final value, to the time the ac
test is past.
PSRR
The maximum change in offset voltage divided by the
total change in supply voltage, in units of mV/V.
7
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Spurious-Free Dynamic Range (SFDR)
The ratio of the power of the fundamental to the highest
other spectral component (either spur or harmonic). SFDR
is typically given in units of dBc (dB to carrier).
8
Two-Tone Intermodulation Distortion
IMD3 is the ratio of the power of the fundamental (at
frequiencies f1, f2) to the power of the worst spectral
component at either frequency 2f1 − f2 or 2f2 − f1). IMD3 is
either given in units of dBc (dB to carrier) when the
absolute power of the fundamental is used as the
reference or dBFS (dB to full scale) when it is referred to
the full-scale range.
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TYPICAL CHARACTERISTICS
Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
SPECTRAL PERFORMANCE
fS = 80 MSPS
fIN = 2 MHz
SNR = 74.5 dBc
SINAD = 74.4 dBc
SFDR = 94 dBc
THD = 93 dBc
−60
−80
5
−60
−80
5 3
4
−120
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
30
f − Frequency − MHz
f − Frequency − MHz
Figure 2
Figure 3
SPECTRAL PERFORMANCE
fS = 80 MSPS
fIN = 70 MHz
SNR = 74 dBc
SINAD = 73.9 dBc
SFDR = 91 dBc
THD = 88 dBc
−60
−80
2
X
5
3
fS = 80 MSPS
fIN = 100 MHz
SNR = 73.4 dBc
SINAD = 72.9 dBc
SFDR = 84 dBc
THD = 82 dBc
−20
Amplitude − dBFS
−40
40
1
0
−20
35
SPECTRAL PERFORMANCE
1
0
Amplitude − dBFS
X
6
−120
−40
−60
−80
3
2
5 X
4
−100
6
−100
4
6
−120
−120
0
5
10
15
20
25
30
35
40
0
5
20
25
30
Figure 4
Figure 5
−40
−60
3
X
79
2
6
−100
40
1
5
fS = 80 MSPS
fIN = 230 MHz
SNR = 70.3 dBc
SINAD = 62.8 dBc
SFDR = 63 dBc
THD = 63 dBc
−20
Amplitude − dBFS
−20
35
SPECTRAL PERFORMANCE
0
fS = 80 MSPS
fIN = 150 MHz
SNR = 71.9 dBc
SINAD = 70.8 dBc
SFDR = 77 dBc
THD = 77 dBc
8
15
f − Frequency − MHz
1
−80
10
f − Frequency − MHz
SPECTRAL PERFORMANCE
0
Amplitude − dBFS
2
−100
6
4
−40
X
2
3
fS = 80 MSPS
fIN = 30 MHz
SNR = 74.3 dBc
SINAD = 74.2 dBc
SFDR = 93 dBc
THD = 89 dBc
−20
Amplitude − dBFS
−40
−100
1
0
−20
Amplitude − dBFS
SPECTRAL PERFORMANCE
1
0
−40
−60
3
2
−80
5
X
4
4
−100
−120
6
−120
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
f − Frequency − MHz
f − Frequency − MHz
Figure 6
Figure 7
30
35
40
9
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TYPICAL CHARACTERISTICS
Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
SPECTRAL PERFORMANCE
SPECTRAL PERFORMANCE
0
0
fS = 80 MSPS
fIN 1 = 69.2 MHz, −7 dBFS
fIN 2 = 70.7 MHz, −7 dBFS
IMD3 = −93 dBFS
−40
fS = 80 MSPS
fIN 1 = 169.6 MHz, −7 dBFS
fIN 2 = 170.4 MHz, −7 dBFS
IMD3 = −81 dBFS
−20
Amplitude − dBFS
Amplitude − dBFS
−20
−60
−80
−100
−120
−40
−60
−80
−100
−120
−140
−140
0
5
10
15
20
25
30
35
40
0
5
10
15
Figure 8
Figure 9
WCDMA CARRIER
35
40
WCDMA CARRIER
fS = 76.8 MSPS
fIN = 70 MHz
PAR = 5 dB
ACPR Adj Top = 79.2 dB
−40
fS = 76.8 MSPS
fIN = 170 MHz
PAR = 5 dB
ACPR Adj Top = 74.8 dB
ACPR Adj Low = 73.9 dB
−20
Amplitude − dBFS
Amplitude − dBFS
30
0
−20
−60
−80
−100
−120
−40
−60
−80
−100
−120
−140
−140
0
5
10
15
20
25
30
35
40
0
5
10
15
f − Frequency − MHz
Figure 11
AC PERFORMANCE
vs
INPUT AMPLITUDE
AC PERFORMANCE
vs
INPUT AMPLITUDE
30
35
40
120
SFDR (dBFS)
100
100
AC Performance − dB
SNR (dBFS)
80
60
SFDR (dBc)
20
SNR (dBc)
0
−20
−90
25
Figure 10
SFDR (dBFS)
40
20
f − Frequency − MHz
120
AC Performance − dB
25
f − Frequency − MHz
0
10
20
f − Frequency − MHz
−70
−60
−50
−40
−30
−20
−10
60
40
SFDR (dBc)
20
SNR (dBc)
0
fS = 80 MSPS
fIN = 70 MHz
−80
SNR (dBFS)
80
0
−20
−90
fS = 80 MSPS
fIN = 170 MHz
−80
−70
−60
−50
−40
−30
−20
AIN − Input Amplitude − dBFS
AIN − Input Amplitude − dBFS
Figure 12
Figure 13
−10
0
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TYPICAL CHARACTERISTICS
TWO-TONE SPURIOUS-FREE DYNAMIC RANGE
vs
INPUT AMPLITUDE
NOISE HISTOGRAM WITH INPUTS SHORTED
120
50
45
100
SFDR (dBFS)
40
Percentage − %
80
60
40
SFDR (dBc)
20
90 dBFS Line
0
−20
−110−100 −90 −80 −70 −60 −50 −40 −30 −20 −10
30
25
20
15
5
0
8174
0
8175
8176
8177
AIN − Input Amplitude − dBFS
Code Number
Figure 14
Figure 15
SPURIOUS-FREE DYNAMIC RANGE
vs
DUTY CYCLE
AC PERFORMANCE
vs
CLOCK LEVEL
100
8178
100
SFDR (dBc)
95
fIN = 2 MHz
95
90
90
85
fIN = 40 MHz
80
85
80
SNR (dBc)
75
70
65
60
fS = 80 MSPS
fIN = 70 MHz
55
75
50
30
40
50
60
70
0
1
2
3
Duty Cycle − %
Clock Level − VPP
Figure 16
Figure 17
AC PERFORMANCE
vs
CLOCK LEVEL
AC PERFORMANCE
vs
CLOCK COMMON MODE
80
100
SFDR
70
AC Performance − dB
SFDR (dBc)
SNR (dBc)
65
60
55
50
1
2
3
90
85
80
SNR
75
70
65
fS = 80 MSPS
fIN = 170 MHz
0
4
fS = 80 MSPS
fIN = 69.6 MHz
95
75
AC Performance − dB
35
10
fIN1 = 69 MHz
fIN2 = 71 MHz
fS = 80 MSPS
AC Performance − dB
SFDR − Spurious-Free Dynamic Range − dBc
SFDR − Two-Tone Spurious-Free Dynamic Range − dB
Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
60
4
0
1
2
3
Clock Level − VPP
Clock Common Mode − V
Figure 18
Figure 19
4
5
11
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
TYPICAL CHARACTERISTICS
SPURIOUS-FREE DYNAMIC RANGE
vs
SUPPLY VOLTAGE
SIGNAL-TO−NOISE RATIO
vs
SUPPLY VOLTAGE
96
74.8
SNR − Signal-to-Noise Ratio − dBc
85°C
60°C
95
94
93
92
91
−40°C
90
89
−20°C
88
87
86
4.6
fS = 80 MSPS
fIN = 69.6 MHz
0°C
4.8
5.0
5.2
−40°C
74.6
74.4
0°C
74.2
40°C
74.0
73.8
73.6
85°C
73.4
73.2
73.0
4.6
5.4
4.8
5.0
5.2
Figure 20
Figure 21
SPURIOUS-FREE DYNAMIC RANGE
vs
SUPPLY VOLTAGE
SIGNAL-TO-NOISE RATIO
vs
SUPPLY VOLTAGE
96
5.4
74.8
95
fS = 80 MSPS
fIN = 69.6 MHz
85°C
40°C
94
93
92
91
−40°C
90
89
0°C
88
2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8
−40°C
74.6
74.4
0°C
20°C
74.2
40°C
74.0
60°C
73.8
73.6
85°C
73.4
73.2
2.6
fS = 80 MSPS
fIN = 69.6 MHz
2.8
3.0
3.2
3.4
AVDD − Supply Voltage − V
IOVDD − Supply Voltage − V
Figure 22
Figure 23
3.6
3.8
INTEGRAL NONLINEARITY
1.5
1.0
0.8
INL − Integral Nonlinearity − LSB
DNL − Differential Nonlinearity − LSB
100°C
AVDD − Supply Voltage − V
DIFFERENTIAL NONLINEARITY
0.6
0.4
0.2
0.0
−0.2
−0.4
−0.6
−0.8
1.0
0.5
0.0
−0.5
−1.0
−1.5
−2.0
−1.0
0
5000
10000
Code
Figure 24
12
fS = 80 MSPS
fIN = 69.6 MHz
AVDD − Supply Voltage − V
SNR − Signal-to-Noise Ratio − dBc
SFDR − Sprious-Free Dynamic Range − dBc
SFDR − Sprious-Free Dynamic Range − dBc
Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
15000
0
5000
10000
Code
Figure 25
15000
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TYPICAL CHARACTERISTICS
Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
TOTAL POWER
vs
SAMPLING FREQUENCY
INPUT BANDWIDTH
5
1.90
IF = 70 MHz
1.89
PT − Total Power − W
Power Output − dB
0
−5
−10
−15
fS = 80 MSPS
AIN = −1dBFS
1.88
1.87
1.86
1.85
1.84
1.83
1.82
−20
1.81
1
10
100
1k
0
20
40
60
80
100
f − Frequency − MHz
fS − Sampling Frequency − MSPS
Figure 26
Figure 27
120
140
13
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Typical values are at TA = 25°C, AVDD = DRVDD = 3.3 V, differential input amplitude = −1 dBFS, sampling rate = 80 MSPS, 3.3 Vpp sinusoidal
clock, 50% duty cycle, 16k FFT points, unless otherwise noted
90
73
71
fS − Sampling Frequency − MHz
80
70
74
72
73
70
60
71
69
74
50
68
72
74
70
40
73
69
71
68
70
30
73
67
69
72
20
71
70
67
68
69
66
20
0
40
60
80
120
100
64
65
10
140
66
160
180
65
63
200
62
220
fIN − Input Frequency − MHz
62
64
66
68
70
72
74
SNR − dBc
Figure 28.
90
94
91
94
94
fS − Sampling Frequency − MHz
80
67
70
82
94
94
73
76
88
94
85
70
94
79
91
94
60
94
94
76
88
50
73
94
94
67
70
40
91
30
91
85
91
94
94
82
79
94
20
64
91
61
70
73
76
85
10
0
20
40
60
80
100
120
140
160
180
fIN − Input Frequency − MHz
60
65
70
75
SFDR − dBc
Figure 29.
14
80
85
90
200
220
ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
EQUIVALENT CIRCUITS
AVDD
AIN
BUF
T/H
AVDD
500 Ω
BUF
1.2 kΩ
500 Ω
AIN
VREF
−
Bandgap
AVDD
25 Ω
+
VREF
BUF
1.2 kΩ
T/H
Figure 33. Reference
Figure 30. Analog Input
DRVDD
AVDD
−
DAC
Bandgap
+
IOUTP
IOUTM
C1, C2
Figure 31. Digital Output
Figure 34. Decoupling Pin
AVDD
DRVDD
10 kΩ
CLK
1 kΩ
Clock Buffer
DMID
Bandgap
AVDD
1 kΩ
10 kΩ
CLK
Figure 32. Clock Input
Figure 35. DMID Generation
15
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APPLICATION INFORMATION
THEORY OF OPERATION
The ADS5423 is a 14 bit, 80 MSPS, monolithic pipeline
analog to digital converter. Its bipolar analog core
operates from a 5 V supply, while the output uses 3.3 V
supply for compatibility with the CMOS family. The
conversion process is initiated by the rising edge of the
external input clock. At that instant, the differential input
signal is captured by the input track and hold (T&H) and
the input sample is sequentially converted by a series
of small resolution stages, with the outputs combined in
a digital correction logic block. Both the rising and the
falling clock edges are used to propagate the sample
through the pipeline every half clock cycle. This process
results in a data latency of three clock cycles, after
which the output data is available as a 14 bit parallel
word, coded in binary two’s complement format.
INPUT CONFIGURATION
The analog input for the ADS5423 (see Figure 30)
consists of an analog differential buffer followed by a
bipolar track-and-hold. The analog buffer isolates the
source driving the input of the ADC from any internal
switching. The input common mode is set internally
through a 500 Ω resistor connected from 2.4 V to each
of the inputs. This results in a differential input
impedance of 1 kΩ.
of 2.2 VPP. The maximum swing is determined by the
internal reference voltage generator eliminating any
external circuitry for this purpose.
The ADS5423 obtains optimum performance when the
analog inputs are driven differentially. The circuit in
Figure 36 shows one possible configuration using an
RF transformer with termination either on the primary or
on the secondary of the transformer. If voltage gain is
required a step up transformer can be used. For higher
gains that would require impractical higher turn ratios on
the transformer, a single-ended amplifier driving the
transformer can be used (see Figure 37). Another
circuit optimized for performance would be the one on
Figure 38, using the THS4304 or the OPA695. Texas
Instruments has shown excellent performance on this
configuration up to 10 dB gain with the THS4304 and at
14 dB gain with the OPA695. For the best performance,
they need to be configured differentially after the
transformer (as shown) or in inverting mode for the
OPA695 (see SBAA113); otherwise, HD2 from the op
amps limits the useful frequency.
R0
50W
VIN
R
50W
AC Signal
Source
RS
100 Ω
OPA695
−
0.1 µF
1000 µF
AIN
Figure 36. Converting a Single-Ended Input to a
Differential Signal Using RF Transformers
RIN
1:1
RT
100 Ω
RIN
AIN
CIN
R1
400 Ω
AV = 8V/V
(18 dB)
Figure 37. Using the OPA695 With the ADS5423
16
ADS5423
ADT1−1WT
−5 V
+
R2
57.5 Ω
AIN
1:1
For a full-scale differential input, each of the differential
lines of the input signal (pins 11 and 12) swings
symmetrically between 2.4 +0.55 V and 2.4 –0.55 V.
This means that each input is driven with a signal of up
to 2.4 ±0.55 V, so that each input has a maximum signal
swing of 1.1 VPP for a total differential input signal swing
5V
Z0
50W
ADS5423
AIN
ADS5423
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
APPLICATION INFORMATION
RG
RF
CM
5V
−
THS4304
+
1:1
VIN
49.9 Ω
CM
From
50 Ω
Source
5V
AIN
ADS5423
VREF
AIN
+
THS4304
−
RG
CM
RF
CM
Figure 38. Using the THS4304 With the ADS5423
Besides these, Texas Instruments offers a wide
selection of single-ended operational amplifiers
(including the THS3201, THS3202, and OPA847) that
can be selected depending on the application. An RF
gain block amplifier, such as Texas Instrument’s
THS9001, can also be used with an RF transformer for
high input frequency applications. For applications
requiring dc-coupling with the signal source, instead of
using a topology with three single ended amplifiers, a
differential input/differential output amplifier like the
THS4509 (see Figure 39) can be used, which
minimizes board space and reduce number of
components.
Figure 41 shows their combined SNR and SFDR
performance versus frequency with −1 dBFS input
signal level and sampling at 80 MSPS.
On this configuration, the THS4509 amplifier circuit
provides 10 dB of gain, converts the single-ended input
to differential, and sets the proper input common-mode
voltage to the ADS5423.
The 225 Ω resistors and 2.7 pF capacitor between the
THS4509 outputs and ADS5423 inputs (along with the
input capacitance of the ADC) limit the bandwidth of the
signal to about 100 MHz (−3 dB).
For this test, an Agilent signal generator is used for the
signal source. The generator is an ac-coupled 50 Ω
source. A band-pass filter is inserted in series with the
input to reduce harmonics and noise from the signal
source.
17
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APPLICATION INFORMATION
Input termination is accomplished via the 69.8 Ω
resistor and 0.22 µF capacitor to ground in conjunction
with the input impedance of the amplifier circuit. A
0.22 µF capacitor and 49.9 Ω resistor is inserted to
ground across the 69.8 Ω resistor and 0.22 µF capacitor
on the alternate input to balance the circuit.
Square Wave or
Sine Wave
From VIN
50 Ω
Source
100 Ω
69.8 Ω
348 Ω
+5V
0.22 µF
100 Ω
49.9 Ω
AIN
ADS5423
AIN VREF
2.7 pF
225 Ω
THS 4509
CM
69.8 Ω
0.22 µF
14-Bit
80 MSPS
225 Ω
49.9 Ω
0.22 µF
0.1 µF
348 Ω
CLK
0.01 µF
Figure 41. Single-Ended Clock
CLOCK INPUTS
The ADS5423 clock input can be driven with either a
differential clock signal or a single-ended clock input,
with little or no difference in performance between both
configurations. In low input frequency applications,
where jitter may not be a big concern, the use of single
ended clock (see Figure 41) could save some cost and
board space without any trade-off in performance.
When driven on this configuration, it is best to connect
CLKM (pin 11) to ground with a 0.01 µF capacitor, while
CLKP is ac-coupled with a 0.01 µF capacitor to the
clock source, as shown in Figure 38.
0.1 µF
0.1 µF
0.01 µF
ADS5423
Gain is a function of the source impedance, termination,
and 348 Ω feedback resistor. See the THS4509 data
sheet for further component values to set proper 50 Ω
termination for other common gains.
Since
the
ADS5423
recommended
input
common-mode voltage is +2.4 V, the THS4509 is
operated from a single power supply input with VS+ =
+5 V and VS− = 0 V (ground). This maintains maximum
headroom on the internal transistors of the THS4509.
CLK
Clock
Source
1:4
CLK
Figure 39. Using the THS4509 With the ADS5423
MA3X71600LCT−ND
ADS5423
CLK
PERFORMANCE
vs
INPUT FREQUENCY
Figure 42. Differential Clock
95
Nevertheless, for jitter sensitive applications, the use of
a differential clock will have some advantages (as with
any other ADCs) at the system level. The first
advantage is that it allows for common-mode noise
rejection at the PCB level. A further analysis (see
Clocking High Speed Data Converters, SLYT075)
reveals one more advantage. The following formula
describes the different contributions to clock jitter:
Performance − dB
90
SFDR (dBc)
85
80
SNR (dBFS)
75
(Jittertotal)2 = (EXT_jitter)2+ (ADC_jitter)2=
(EXT_jitter) 2 + (ADC_int)2 + (K/clock_slope)2
70
10
20
30
40
50
60
70
fIN − Input Frequency − MHz
Figure 40. Performance vs Input Frequency for
the THS4509 + ADS5423 Configuration
18
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SLWS160A − FEBRUARY 2005 − REVIISED JANUARY 2010
APPLICATION INFORMATION
The first term would represent the external jitter, coming
from the clock source, plus noise added by the system
on the clock distribution, up to the ADC. The second
term is the ADC contribution, which can be divided in
two portions. The first does not depend directly on any
external factor. That is the best we can get out of our
ADC. The second contribution is a term inversely
proportional to the clock slope. The faster the slope, the
smaller this term will be. As an example, we could
compute the ADC jitter contribution from a sinusoidal
input clock of 3 Vpp amplitude and Fs = 80 MSPS:
Another possibility is the use of a logic based clock, as
PECL. In this case, the slew rate of the edges will most
likely be much higher than the one obtained for the
same clock amplitude based on a sinusoidal clock. This
solution would minimize the effect of the slope
dependent ADC jitter. Nevertheless, observe that for
the ADS5423, this term is small and has been
optimized. Using logic gates to square a sinusoidal
clock may not produce the best results as logic gates
may not have been optimized to act as comparators,
adding too much jitter while squaring the inputs.
ADC_jitter = sqrt ((150fs)2+ (5 x 10−5/(1.5 x 2 x PI x 80
x 106))2) = 164fs
The common-mode voltage of the clock inputs is set
internally to 2.4 V using internal 1 kΩ resistors. It is
recommended using an ac coupling, but if for any
reason, this scheme is not possible, due to, for
instance, asynchronous clocking, the ADS5423
presents a good tolerance to clock common-mode
variation (see Figure 19).
The use of differential clock allows for the use of bigger
clock amplitudes without exceeding the absolute
maximum ratings. This, on the case of sinusoidal clock,
results on higher slew rates which minimizes the impact
of the jitter factor inversely proportional to the clock
slope.
Figure 42 shows this approach. The back-to-back
Schottky can be added to limit the clock amplitude in
cases where this would exceed the absolute maximum
ratings, even when using a differential clock. Figure 17
and Figure 18 show the performance versus input clock
amplitude for a sinusoidal clock.
100 nF
MC100EP16DT
100 nF
D
D
CLK
VBB Q
499 W
100 nF
Q
100 nF
ADS5423
CLK
499 W
50 Ω
50 Ω
100 nF
113 Ω
Figure 43. Differential Clock Using PECL Logic
Additionally, the internal ADC core uses both edges of
the clock for the conversion process. This means that,
ideally, a 50% duty cycle should be provided. Figure 16
shows the performance variation of the ADC versus
clock duty cycle.
DIGITAL OUTPUTS
The ADC provides 14 data outputs (D13 to D0, with D13
being the MSB and D0 the LSB), a data-ready signal
(DRY, pin 52), and an out-of-range indicator (OVR, pin
32) that equals 1 when the output reaches the full-scale
limits.
The output format is two’s complement. When the input
voltage is at negative full scale (around −1.1 V
differential), the output will be, from MSB to LSB, 10
0000 0000 0000. Then, as the input voltage is
increased, the output switches to 10 0000 0000 0001,
10 0000 0000 0010 and so on until 11 1111 1111 1111
right before mid-scale (when both inputs are tight
together if we neglect offset errors). Further increase on
input voltages, outputs the word 00 0000 0000 0000, to
be followed by 00 0000 0000 0001, 00 0000 0000 0010
and so on until reaching 01 1111 1111 1111 at full-scale
input (1.1 V differential).
19
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APPLICATION INFORMATION
Although the output circuitry of the ADS5423 has been
designed to minimize the noise produced by the
transients of the data switching, care must be taken
when designing the circuitry reading the ADS5423
outputs. Output load capacitance should be minimized
by minimizing the load on the output traces, reducing
their length and the number of gates connected to them,
and by the use of a series resistor with each pin. Typical
numbers on the data sheet tables and graphs are
obtained with 100 Ω series resistor on each digital
output pin, followed by a 74AVC16244 digital buffer as
the one used in the evaluation board.
POWER SUPPLIES
The use of low noise power supplies with adequate
decoupling is recommended, being the linear supplies
the first choice vs switched ones, which tend to
generate more noise components that can be coupled
to the ADS5423.
The ADS5423 uses two power supplies. For the analog
portion of the design, a 5 V AVDD is used, while for the
digital outputs supply (DRVDD), we recommend the use
of 3.3 V. All the ground pins are marked as GND,
although AGND pins and DRGND pins are not tied
together inside the package. Customers willing to
experiment with different grounding schemes should
know that AGND pins are 4, 7, 10, 13, 15, 17, 19, 21,
23, 25, 27, and 29, while DRGND pins are 2, 34, and 42.
Nevertheless, we recommend that both grounds are
tied together externally, using a common ground plane.
That is the case on the production test boards and
20
modules provided to customer for evaluation. In order
to obtain the best performance, the user should layout
the board to assure that the digital return currents do not
flow under the analog portion of the board. This can be
achieved without the need to split the board and just
with careful component placing and increasing the
number of vias and ground planes.
Finally, notice that the metallic heat sink under the
package is also connected to analog ground.
LAYOUT INFORMATION
The evaluation board represents a good guideline of
how to layout the board to obtain the maximum
performance out of the ADS5423. General design rules
as the use of multilayer boards, single ground plane for
both, analog and digital ADC ground connections and
local decoupling ceramic chip capacitors should be
applied. The input traces should be isolated from any
external source of interference or noise, including the
digital outputs as well as the clock traces. The clock
should also be isolated from other signals, especially on
applications where low jitter is required, as high IF
sampling.
Besides performance oriented rules, special care has
to be taken when considering the heat dissipation out
of the device. The thermal heat sink (octagonal, with
2,5 mm on each side) should be soldered to the board,
and provision for more than 16 ground vias should be
made. The thermal package information describes the
TJA values obtained on the different configurations.
PACKAGE OPTION ADDENDUM
www.ti.com
6-Feb-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
ADS5423IPGP
ACTIVE
HTQFP
PGP
52
160
Green (RoHS
& no Sb/Br)
NIPDAU
Level-3-260C-168 HR
-40 to 85
ADS5423IPGP
ADS5423IPGPR
ACTIVE
HTQFP
PGP
52
1000
Green (RoHS
& no Sb/Br)
NIPDAU
Level-3-260C-168 HR
-40 to 85
ADS5423IPGP
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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