THS4521-HT
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SBOS548D – APRIL 2011 – REVISED MAY 2012
VERY LOW POWER, NEGATIVE RAIL INPUT,
RAIL-TO-RAIL OUTPUT, FULLY DIFFERENTIAL AMPLIFIER
Check for Samples: THS4521-HT
FEATURES
1
•
•
•
•
•
•
•
•
•
•
•
•
Fully Differential Architecture
Bandwidth: 40.7 MHz (210°C)
Slew Rate: 353.5 V/μs (210°C)
HD2: –96 dBc at 1 kHz
(1 VRMS, RL = 1 kΩ) (210°C)
HD3: –91.5 dBc at 1 kHz
(1 VRMS, RL = 1 kΩ) (210°C)
Input Voltage Noise: 19.95 nV/√Hz (f = 100 kHz)
Open-Loop Gain: 90 dB (typ) (210°C)
NRI—Negative Rail Input
RRO—Rail-to-Rail Output
Output Common-Mode Control (with Low
Offset and Drift)
Power Supply:
– Voltage: 2.5 V (±1.25 V) to 3.3 V (±1.65 V)
– Current: 1.4 mA/ch (3.3 V)
Power-Down Capability: 10 µA (typ) (210°C)
APPLICATIONS
•
•
Down-Hole Drilling
High Temperature Environments
SUPPORTS EXTREME TEMPERATURE
APPLICATIONS
•
•
•
•
•
•
•
•
(1)
Controlled Baseline
One Assembly/Test Site
One Fabrication Site
Available in Extreme (–55°C/210°C)
Temperature Range (1)
Extended Product Life Cycle
Extended Product-Change Notification
Product Traceability
Texas Instruments high temperature products
utilize highly optimized silicon (die) solutions
with design and process enhancements to
maximize performance over extended
temperatures.
Custom temperature ranges available
DESCRIPTION
The THS4521 is a very low-power, fully differential op amp with rail-to-rail output and an input common-mode
range that includes the negative rail. This amplifier is designed for low-power data acquisition systems and highdensity applications where power dissipation is a critical parameter, and provides exceptional performance in
audio applications.
The THS4521 features accurate output common-mode control that allows for dc-coupling when driving analog-todigital converters (ADCs). This control, coupled with an input common-mode range below the negative rail as
well as rail-to-rail output, allows for easy interfacing between single-ended, ground-referenced signal sources.
Additionally, this device is ideally suited for driving both successive-approximation register (SAR) and deltasigma (ΔΣ) ADCs using only a single 2.5-V to 3.3-V and ground power supply.
The THS4521 is characterized for operation from –55°C to 210°C.
1
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.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2011–2012, Texas Instruments Incorporated
THS4521-HT
SBOS548D – APRIL 2011 – REVISED MAY 2012
www.ti.com
1 kW
1.5 nF
49.9 W
1 kW
AINP1
VIN+
THS4521
VIN-
49.9 W
2.2 nF
ADS1278 (CH 1)
AINN1
1 kW
1.5 nF
Magnitude (dBV)
3.3 V
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
0
2k
1 kW
2
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4k
6k
8k 10k 12k 14k 16k 18k 20k
Frequency (Hz)
Copyright © 2011–2012, Texas Instruments Incorporated
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SBOS548D – APRIL 2011 – REVISED MAY 2012
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.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
BARE DIE INFORMATION
BACKSIDE FINISH
BACKSIDE
POTENTIAL
BOND PAD
METALLIZATION COMPOSITION
BOND PAD
THICKNESS
11 mils.
Silicon with backgrind
Floating
Al-Cu (0.5%)
1380 nm
½
½
922 mm
12
10
11
9
½
DIE THICKNESS
8
76.8 mm
|
809 mm
7
6
3
2
1
0.0
4
5
½
|
75.8 mm
0.0
Table 1. Bond Pad Coordinates in Microns
DISCRIPTION
PAD NUMBER
X min
Y min
X max
Y max
VIN-
1
80.7
3.7
165.7
88.7
VOCM
2
310.6
3.7
395.6
88.7
VS+
3
405.6
3.7
490.6
88.7
VS+
4
500.6
3.7
585.6
88.7
VS+
5
595.6
3.7
680.6
88.7
VOUT+
6
679.6
137.55
764.6
222.55
VOUT-
7
679.6
434.7
764.6
519.7
VS-
8
595.6
568.6
680.6
653.6
VS-
9
500.6
568.6
585.6
653.6
VS-
10
405.6
568.6
490.6
653.6
PD
11
310.6
568.6
395.6
653.6
VIN+
12
80.7
568.6
165.7
653.6
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ORDERING INFORMATION (1)
PACKAGE (2)
TA
–55°C to175°C
(2)
TOP-SIDE MARKING
THS4521
D
THS4521HD
KGD (bare die)
THS4521SKGD1
NA
HKJ
THS4521SHKJ
THS4521SHKJ
HKQ
THS4521SHKQ
THS4521SHKQ
–55°C to 210°C
(1)
ORDERABLE PART NUMBER
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.
Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range (unless otherwise noted).
UNIT
Supply Voltage, VS– to VS+
Input/Output Voltage, VI (VIN±, VOUT±, VOCM pins)
3.6
V
(VS–) – 0.7 to (VS+) + 0.7V
V
Differential Input Voltage, VID
Output Current, IO
Input Current, II (VIN±, VOCM pins)
Continuous Power Dissipation
Operating Free-air Temperature Range, TA
10
mA
217
°C
–40 to 175
KGD, HKJ, HKQ packages
–55 to 210
°C
–65 to 210
°C
Human Body Model (HBM)
1300
V
Charge Device Model (CDM)
1000
V
50
V
Machine Model (MM)
(2)
mA
D package
Storage Temperature Range, TSTG
(1)
V
100
See Thermal Characteristic Specifications
Maximum Junction Temperature, TJ (continuous operation, long-term reliability) (2)
ESD
Rating:
1
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated is not implied. Exposure to absolutemaximum-rated conditions for extended periods may affect device reliability.
Refer to Figure 1 for expected life time.
THERMAL CHARACTERISTICS FOR D PACKAGE
over operating free-air temperature range (unless otherwise noted)
PARAMETER
θJC (1)
Junction-to-case thermal resistance
θJA
Junction-to-ambient thermal resistance
(1)
MIN
TYP
MAX
UNIT
72.5
°C/W
118.5
°C/W
Taken as per JESD51.
THERMAL CHARACTERISTICS FOR HKJ OR HKQ PACKAGE
over operating free-air temperature range (unless otherwise noted)
PARAMETER
θJC
4
Junction-to-case thermal resistance
to ceramic side of case
to top of case lid (metal side of case)
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MIN
TYP
MAX
5.7
13.7
UNIT
°C/W
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SBOS548D – APRIL 2011 – REVISED MAY 2012
ELECTRICAL CHARACTERISTICS: VS+ – VS– = 3.3 V
At VS+ = 3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, input and output referenced to midsupply, unless otherwise noted.
-55°C to 125°C
PARAMETER
CONDITIONS
MIN
TYP
MAX
175°C
MIN
TYP
-55°C to 210°C
MAX
MIN
TYP
MAX
UNIT
TEST
LEVEL (1)
AC PERFORMANCE
VOUT = 100 mVPP,
G=1
104.3
40.7
40.7
MHz
C
VOUT = 100 mVPP,
G=2
42
12.5
12.5
MHz
C
VOUT = 100 mVPP,
G=5
12.2
3.15
3.15
MHz
C
VOUT = 100 mVPP,
G = 10
8.1
2.2
2.2
MHz
C
VOUT = 100 mVPP,
G = 10
81
22
22
MHz
C
Large-Signal Bandwidth
VOUT = 2 VPP, G = 1
84
22
22
MHz
C
Bandwidth for 0.1-dB
Flatness
VOUT = 2 VPP, G = 1
18.1
5.4
5.4
MHz
C
Rising Slew Rate
(Differential)
VOUT = 2-V Step,
G = 1, RL = 200 Ω
377.5
353.5
353.5
V/μs
C
Falling Slew Rate
(Differential)
VOUT = 2-V Step,
G = 1, RL = 200 Ω
422.5
392.5
392.5
V/μs
C
Overshoot
VOUT = 2-V Step,
G = 1, RL = 200 Ω
6.75
8.85
8.85
%
C
Undershoot
VOUT = 2-V Step,
G = 1, RL = 200 Ω
7.85
11.45
11.45
%
C
Rise Time
VOUT = 2-V Step,
G = 1, RL = 200 Ω
13.5
15.9
15.9
ns
C
Fall Time
VOUT = 2-V Step,
G = 1, RL = 200 Ω
11.4
14.6
14.6
ns
C
Settling Time to 1%
VOUT = 2-V Step,
G = 1, RL = 200 Ω
18.5
23.5
23.5
ns
C
f = 1 kHz,
VOUT = 1 VRMS,
G = 1 (2),
differential input
–115
–96
–96
dBc
C
f = 1 MHz,
VOUT = 2 VPP, G = 1
–77
–68.5
–68.5
dBc
C
f = 1 kHz,
VOUT = 1 VRMS,
G = 1 (2),
differential input
–116
–91.5
–91.5
dBc
C
f = 1 MHz,
VOUT = 2 VPP, G = 1
–80.5
–68.5
–68.5
dBc
C
Second-Order
Intermodulation
Distortion
Two-tone, f1 = 2 kHz,
f2 = 500 Hz,
VOUT = 1 VRMS envelope
–91.5
–79.5
–79.5
dBc
C
Third-Order
Intermodulation
Distortion
Two-tone, f1 = 2 kHz,
f2 = 500 Hz,
VOUT = 1 VRMS envelope
–95.5
–79.5
–79.5
dBc
C
Input Voltage Noise
f > 10 kHz
9.05
19.95
19.95
nV/√Hz
C
Input Current Noise
f > 100 kHz
1.8
2.45
2.45
pA/√Hz
C
Overdrive Recovery
Time
Overdrive = ±0.5 V
116.5
126
126
ns
C
Output Balance Error
VOUT = 100 mV,
f ≤ 2 MHz (differential input)
–51.5
–45.5
–45.5
dB
C
Closed-Loop Output
Impedance
f = 1 MHz (differential)
0.3
Ω
C
Small-Signal Bandwidth
Gain Bandwidth
Product
HARMONIC DISTORTION
2nd harmonic
3rd harmonic
(1)
(2)
Test levels: (A) 100% tested. (B) Limits set by characterization and simulation. (C) Typical value only for information.
Not directly measureable; calculated using noise gain of 101.
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ELECTRICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = 3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, input and output referenced to midsupply, unless otherwise noted.
-55°C to 125°C
PARAMETER
CONDITIONS
MIN
TYP
175°C
MAX
MIN
TYP
-55°C to 210°C
MAX
MIN
TYP
MAX
UNIT
TEST
LEVEL (1)
dB
A
DC PERFORMANCE
Open-Loop Voltage
Gain (AOL)
102
Input-Referred Offset
Voltage
±0.1
Input offset voltage
drift (3)
81.9
90
±5
±0.13
±0.43
±11.5
mV
A
±1
±28
±10
±2
±50
μV/°C
B
Input Bias Current
±0.75
±3.3
±0.75
±0.78
±4.5
μA
A
Input bias current
drift (3)
±3.3
±14
±4.7
±4.8
±17
nA/°C
B
Input Offset Current
±0.3
±1.7
±0.5
±0.5
±3.5
µA
A
Input offset current
drift (3)
±1.1
±8
±3.6
±1.26
±9
nA/°C
B
–0.1
0
-0.1
–0.1
0
V
A
±4.5
±3.2
INPUT
Common-Mode Input
Voltage Low
Common-Mode Input
Voltage High
1.8
1.9
1.9
1.8
1.9
V
A
Common-Mode
Rejection Ratio
(CMRR)
80
105
95
74
98
dB
A
154∥3.
2
12.3∥4
6
12.3∥4
6
kΩ∥pF
C
V
A
V
A
mA
C
Input Resistance
OUTPUT
Output Voltage Low
0.09
Output Voltage High
2.95
Output Current Drive
(for linear operation)
RL = 50 Ω
0.25
0.3
3.11
±35
0.09
3.11
(4)
±33
2.85
(4)
0.31
3.05
±33
(4)
POWER SUPPLY
Specified Operating
Voltage
2.5
Quiescent Operating
Current, per channel
0.85
1
66
85
Power-Supply
Rejection Ratio
(±PSRR)
3.6
2.5
1.3
0.9
1.16
62.5
74
3.6
2.5
3.6
1.4
0.9
1.1
60
80
1.4
V
A
mA
A
dB
A
V
A
1.6
V
A
POWER DOWN
Enable Voltage
Threshold
Assured on
above 2.2 V
Disable Voltage
Threshold
Assured off
below 0.7 V
1
0.7
1.6
2.2
1
0.7
1.6
2.2
1
0.7
2.2
Disable Pin Bias
Current
1
1
1
μA
C
Power Down Quiescent
Current
2
10
10
μA
C
Turn-On Time Delay
Time to VOUT = 90% of final
value, VIN= 2 V, RL = 200 Ω
86.5
99
99
ns
C
Turn-Off Time Delay
Time to VOUT = 10% of
original value,
VIN= 2 V, RL = 200 Ω
136
145
144.5
ns
C
21
13
13
MHz
C
VOCM VOLTAGE CONTROL
Small-Signal Bandwidth
(3)
(4)
6
Input Offset Voltage Drift, Input Bias Current Drift and Input Offset Current Drift are average values calculated by taking data at -55°C
and 125°C, computing the difference and dividing by 180. High temperature drift data is an average value calculated by taking data at 55°C and 210°C, computing the difference and diving by 265.
Continuous operation with high current loads at elevated temperature may affect product reliability. Refer to operating lifetime chart
(Figure 1).
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SBOS548D – APRIL 2011 – REVISED MAY 2012
ELECTRICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = 3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, input and output referenced to midsupply, unless otherwise noted.
-55°C to 125°C
PARAMETER
CONDITIONS
MIN
TYP
0.97
Slew Rate
175°C
MAX
MIN
TYP
0.99
1.02
0.97
±0.2
±4
±0.9
±2.73
±0.27
2.3
0.8 to
2.5
49
Gain
Common-Mode Offset
Voltage from VOCM
Input
Measured at VOUT with VOCM
input driven, VOCM = 1.65 V
±0.5 V
Input Bias Current
VOCM = 1.65 V ±0.5 V
VOCM Voltage Range
1.01
0.8 to
2.5
Default Output
Common-Mode Voltage
Offset from
(VS+– VS–)/2
Measured at VOUT
with VOCM input open
±0.3
MIN
1.03
0.97
39
±0.7
±2.75
1.09
148∥3.
7
±5
TYP
MAX
UNIT
TEST
LEVEL (1)
39
1
114∥3.
6
Input Impedance
-55°C to 210°C
MAX
±0.6
V/μs
C
1
1.03
V/V
A
±0.7
±10
mV
A
±0.91
±2.75
μA
A
0.8 to
2.5
2.3
V
A
kΩ∥pF
C
mV
A
148∥3.
7
±10
±0.6
±10
1000000
Estimated Life - Hours
100000
Output Load = 10 mA
10000
Output Load = 25 mA
Output Load = 35 mA
1000
100
110
120
130
140
150
160
170
180
190
200
210
220
Continuous TJ - °C
(1)
See data sheet for absolute maximum and minimum recommended operating conditions.
(2)
Silicon operating life design goal is 10 years at 105°C junction temperature (does not include package interconnect
life).
(3)
The predicted operating lifetime vs. junction temperature is based on reliability modeling using electromigration as the
dominant failure mechanism affecting device wearout for the specific device process and design characteristics.
(4)
Device is qualified to ensure reliable operation for 1000 hours at maximum rated temperature. This includes, but is
not limited to temperature bake, temperature cycle, electromigration, bond intermetallic life, and mold compound life.
Such qualification testing should not be viewed as justifying use of this component beyond specified performance and
environmental limits. For plastic package only.
Figure 1. THS4521SHKJ/SHKQ/SKGD1 Operating Life Derating Chart
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DEVICE INFORMATION
HKQ PACKAGE
(TOP VIEW)
D OR HKJ PACKAGE
(TOP VIEW)
VIN- 1
8
VIN+
VOCM 2
7
PD
VS+ 3
6
VS-
VOUT+ 4
5
VOUT-
VIN+
8
1
VIN-
PD
VOCM
VS-
VS+
VOUT-
5
4
VOUT+
HKQ as formed or HKJ mounted dead bug
TERMINAL FUNCTIONS
PIN NO.
8
NAME
DESCRIPTION
1
VIN–
2
VOCM
Inverting amplifier input
3
VS+
4
VOUT+
Noninverting amplifier output
5
VOUT–
Inverting amplifier output
6
VS–
Amplifier negative power-supply input. Note that VS– is tied together on multi-channel devices.
7
PD
Power down. PD = logic low puts device into low-power mode. PD = logic high or open for normal
operation.
8
VIN+
Noninverting amplifier input
Common-mode voltage input
Amplifier positive power-supply input
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SBOS548D – APRIL 2011 – REVISED MAY 2012
TYPICAL CHARACTERISTICS
Table of Graphs (1): VS+ – VS– = 3.3 V
TITLE
FIGURE
Small-Signal Frequency Response
Figure 2
Large-Signal Frequency Response
Figure 3
Large- and Small-Signal Pulse Response
Figure 4
Slew Rate vs VOUT Step
Figure 5
Overdrive Recovery
Figure 6
10-kHz Output Spectrum on AP Analyzer
Figure 7
Harmonic Distortion vs Frequency
Figure 8
Harmonic Distortion vs Output Voltage at 1 MHz
Figure 9
Harmonic Distortion vs Gain at 1 MHz
Figure 10
Harmonic Distortion vs Load at 1 MHz
Figure 11
Harmonic Distortion vs VOCM at 1 MHz
Figure 12
Two-Tone, Second- and Third-Order Intermodulation Distortion vs Frequency
Figure 13
Single-Ended Output Voltage Swing vs Load Resistance
Figure 14
Main Amplifier Differential Output Impedance vs Frequency
Figure 15
Frequency Response vs CLOAD (RLOAD = 1 kΩ)
Figure 16
RO vs CLOAD (RLOAD = 1 kΩ)
Figure 17
Rejection Ratio vs Frequency
Figure 18
Turn-on Time
Figure 19
Turn-off Time
Figure 20
Input-Referred Voltage Noise and Current Noise Spectral Density
Figure 21
Main Amplifier Differential Open-Loop Gain and Phase
Figure 22
Output Balance Error vs Frequency
Figure 23
VOCM Small-Signal Frequency Response
Figure 24
VOCM Large-Signal Frequency Response
Figure 25
VOCM Input Impedance vs Frequency
Figure 26
(1)
Graphs are plotted for room temperature only and are given only for reference.
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TYPICAL CHARACTERISTICS: VS+ – VS– = 3.3 V
At VS+ = +3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, and input and output referenced to midsupply, unless otherwise noted. Graphs are plotted for room
temperature only and are given only for reference.
SMALL-SIGNAL FREQUENCY RESPONSE
LARGE-SIGNAL FREQUENCY RESPONSE
6
6
3
G = 1 V/V
0
-3
Normalized Gain (dB)
Normalized Gain (dB)
3
G = 2 V/V
-6
G = 5 V/V
-9
-12
G = 10 V/V
-15
VS+ = 3.3 V
RL = 1 kW
VO = 100 mVPP
-18
-21
-24
100 k
G = 1 V/V
0
G = 2 V/V
-3
-6
G = 5 V/V
-9
-12
G = 10 V/V
-15
VS+ = 3.3 V
RL = 1 kW
VO = 2.0 VPP
-18
-21
1M
10 M
100 M
-24
100 k
1G
Rising
500
0
Slew Rate (V/ms)
Differential VOUT (V)
SLEW RATE vs VOUT
600
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 200 W
0.5
0.5-V Step
-0.5
400
Falling
300
200
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 200 W
2-V Step
-1.0
100
-1.5
0
0
20
40
60
80
100
0
1
Figure 5.
OVERDRIVE RECOVERY
10-kHz OUTPUT SPECTRUM ON
AP ANALYZER
1.5
1.0
1
0.5
0
0
-1
-0.5
VS+ = 3.3 V
G = 2 V/V
RF = 1 kW
RL = 200 W
0
100 200
-1.0
-1.5
-2.0
300 400 500 600
800
900
1k
Input Voltage (V)
2
Magnitude (dBv)
3
Differential VOUT (V)
2.0
VOUT Diff
Input
-4
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
VOUT = 5 VPP
0
Time (ns)
5k
Generator
THS4521
10 k
15 k
20 k
25 k
30 k
35 k
Frequency (Hz)
Figure 6.
10
5
4
Differential VOUT (V)
Figure 4.
4
-3
3
2
Time (ns)
-2
1G
Figure 3.
LARGE- AND SMALL-SIGNAL PULSE RESPONSE
1.0
100 M
Frequency (Hz)
Figure 2.
1.5
10 M
1M
Frequency (Hz)
Figure 7.
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TYPICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = +3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, and input and output referenced to midsupply, unless otherwise noted. Graphs are plotted for room
temperature only and are given only for reference.
HARMONIC DISTORTION
vs VOUT AT 1 MHZ
HARMONIC DISTORTION vs FREQUENCY
Harmonic Distortion (dBc)
-50
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 1 kW
VOUT = 2.0 VPP
-20
-30
-40
-50
Third
Harmonic
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 1 kW
f = 1 MHz
-55
Harmonic Distortion (dBc)
-10
Second
Harmonic
-60
-70
-80
-90
-100
-60
-65
-70
-75
Second
Harmonic
-80
-85
-90
Third
Harmonic
-95
-110
-100
10
1
100
1
3
2
Frequency (MHz)
Figure 8.
Figure 9.
HARMONIC DISTORTION
vs GAIN AT 1 MHZ
HARMONIC DISTORTION
vs LOAD AT 1 MHZ
-70
6
5
-70
-75
Second
Harmonic
-80
-85
VS+ = 3.3 V
RF = 1 kW
RL = 1 kW
f = 1 MHz
VOUT = 2.0 VPP
Third
Harmonic
-90
-95
-100
Harmonic Distortion (dBc)
Harmonic Distortion (dBc)
4
VOUT (VPP)
-75
Second
Harmonic
-80
-85
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
f = 1 MHz
VOUT = 2.0 VPP
-90
-95
Third
Harmonic
-100
1
2
3
4
5
6
7
8
9
10
0
100 200
300 400 500 600
800
900
1k
Load (W)
Gain (V/V)
Figure 10.
Figure 11.
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TYPICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = +3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, and input and output referenced to midsupply, unless otherwise noted. Graphs are plotted for room
temperature only and are given only for reference.
HARMONIC DISTORTION
vs VOCM AT 1 MHZ
-10
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 1 kW
f = 1 MHz
VOUT = 2.0 VPP
-40
-50
-60
-70
Second
Harmonic
-80
-90
Third
Harmonic
-100
0
0.5
1.0
1.5
2.0
2.5
Intermodulation Distortion (dBc)
Harmonic Distortion (dBc)
-30
TWO-TONE INTERMODULATION DISTORTION
vs FREQUENCY
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 1 kW
VOUT = 2.0 VPP
envelope
-20
-30
-40
-50
-60
-70
Third
Intermodulation
-80
-90
-100
-110
3.0
Figure 12.
Figure 13.
SINGLE-ENDED OUTPUT VOLTAGE SWING
vs LOAD RESISTANCE
MAIN AMPLIFIER DIFFERENTIAL OUTPUT IMPEDANCE
vs FREQUENCY
100
Linear Voltage Range
VOCM = 1.65 V
2.5
VOUT max
2.0
1.5
VOUT min
1.0
0.5
0
10
100
1k
10 k
10
1
0.1
0.01
100 k
10 M
1M
100 M
Frequency (Hz)
Load Resistance (W)
Figure 14.
12
100
Frequency (MHz)
Differential Output Impedance (W)
Single-Ended VOUT (V)
3.0
10
1
VOCM (V)
3.5
Second
Intermodulation
Figure 15.
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TYPICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = +3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, and input and output referenced to midsupply, unless otherwise noted. Graphs are plotted for room
temperature only and are given only for reference.
FREQUENCY RESPONSE vs CLOAD
RLOAD = 1 kΩ
RO vs CLOAD
RLOAD = 1 kΩ
1k
5
CL = 4.7 pF
RO = 150 W
CL = 1000 pF
RO = 7.15 W
-5
-10
100
RO (W)
Normalized Gain (dB)
0
CL = 100 pF
RO = 35.7 W
10
-15
CL = 10 pF
RO = 124 W
-20
1
-25
100 k
1M
100 M
10 M
10
1G
100
Frequency (Hz)
Figure 16.
Figure 17.
REJECTION RATIO vs FREQUENCY
TURN-ON TIME
4.0
3.5
100
3.0
PD Pulse (V)
90
80
CMRR
70
50
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
10 k
2.5
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 200 W
2.0
2.5
1.5
2.0
1.0
1.5
VOUT Diff
PD
1.0
-PSRR
0
0
10 M
1M
0
100 M
20
40
60
2.0
1.8
1.6
1.2
2.0
1.0
1.5
0.8
0.6
1.0
VOUT Diff
PD
0.5
0.4
0.2
0
0
80
100 120
140 160
180 200
Differential VOUT (V)
1.4
Input-Referred Voltage Noise (nV/ÖHz)
Input-Referred Current Noise (pA/ÖHz)
INPUT-REFERRED VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY
2.5
PD Pulse (V)
180 200
TURN-OFF TIME
3.0
60
140 160
Figure 19.
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 200 W
40
100 120
Figure 18.
3.5
20
80
Time (ns)
Frequency (Hz)
0
0.5
0.5
+PSRR
100 k
Differential VOUT (V)
Common-Mode Rejection Ratio (dB)
Power-Supply Rejection Ratio (dB)
110
60
1000
CLOAD (pF)
100
10
Voltage
Noise
1
Current
Noise
0
10
100
1k
10 k
100 k
1M
Frequency (Hz)
Time (ns)
Figure 20.
Figure 21.
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TYPICAL CHARACTERISTICS: VS+ – VS– = 3.3 V (continued)
At VS+ = +3.3 V, VS– = 0 V, VOCM = open, VOUT = 2 VPP (differential), RL = 1 kΩ differential, G = 1 V/V, single-ended input,
differential output, and input and output referenced to midsupply, unless otherwise noted. Graphs are plotted for room
temperature only and are given only for reference.
MAIN AMPLIFIER
DIFFERENTIAL OPEN-LOOP GAIN AND PHASE
OUTPUT BALANCE ERROR
vs FREQUENCY
0
120
-20
Gain
-45
60
40
-90
20
Phase
0
Output Balance Error (dB)
OPen-Loop Gain (dB)
80
Open-Loop Phase (Degrees)
100
-20
10
100
1k
10 k
100 k
1M
-30
-35
-40
-45
-50
-55
-135
1
G = 0 dB
-25
-60
100 k
10 M 100 M
100 M
Frequency (Hz)
Figure 22.
Figure 23.
VOCM SMALL-SIGNAL FREQUENCY RESPONSE
VOCM LARGE-SIGNAL PULSE RESPONSE
0
VOUT Common-Mode Voltage (V)
2.5
-5
Gain (dB)
10 M
1M
Frequency (Hz)
-10
-15
G = 0 dB
VIN = -20 dBm
-20
100 k
1M
2.3
2.1
1.9
1.7
1.5
1.3
1.1
VS+ = 3.3 V
G = 1 V/V
RF = 1 kW
RL = 1 kW
0.9
0.7
0.5
10 M
100 M
1G
0
100
Frequency (Hz)
200
300
400
Time (ns)
Figure 24.
Figure 25.
VOCM INPUT IMPEDANCE
vs FREQUENCY
VOCM Input Impedance (W)
100 k
10 k
1k
100
100 k
10 M
1M
100 M
Frequency (Hz)
Figure 26.
14
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TEST CIRCUITS
Overview
The THS4521 is tested with the test circuits shown in
this section; all circuits are built using the available
THS4521 evaluation module (EVM). For simplicity,
power-supply decoupling is not shown; see the layout
in the Applications section for recommendations.
Depending on the test conditions, component values
change in accordance with Table 2 and Table 3, or
as otherwise noted. In some cases the signal
generators used are ac-coupled and in others they
dc-coupled 50-Ω sources. To balance the amplifier
when ac-coupled, a 0.22-μF capacitor and 49.9-Ω
resistor to ground are inserted across RIT on the
alternate input; when dc-coupled, only the 49.9-Ω
resistor to ground is added across RIT. A split power
supply is used to ease the interface to common test
equipment, but the amplifier can be operated in a
single-supply configuration as described in the
Applications section with no impact on performance.
Also, for most of the tests, except as noted, the
devices are tested with single-ended inputs and a
transformer on the output to convert the differential
output to single-ended because common lab test
equipment has single-ended inputs and outputs.
Similar or better performance can be expected with
differential inputs and outputs.
As a result of the voltage divider on the output formed
by the load component values, the amplifier output is
attenuated. The Atten column in Table 3 shows the
attenuation expected from the resistor divider. When
using a transformer at the output (as shown in
Figure 28), the signal sees slightly more loss because
of transformer and line loss; these numbers are
approximate.
Ω input termination.
Table 3. Load Component Values For 1:1
Differential to Single-Ended Output Transformer(1)
RL
RO
ROT
100 Ω
24.9 Ω
Open
6 dB
200 Ω
86.6 Ω
69.8 Ω
16.8 dB
499 Ω
237 Ω
56.2 Ω
25.5 dB
1 kΩ
487 Ω
52.3 Ω
31.8 dB
1. Total load includes 50-Ω termination by the test
equipment. Components are chosen to achieve
load and 50-Ω line termination through a 1:1
transformer.
Frequency Response
The circuit shown in Figure 27 is used to measure the
frequency response of the circuit.
An HP network analyzer is used as the signal source
and the measurement device. The output impedance
of the HP network analyzer is is dc-coupled and is
50 Ω. RIT and RG are chosen to impedance-match to
50 Ω and maintain the proper gain. To balance the
amplifier, a 49.9-Ω resistor to ground is inserted
across RIT on the alternate input.
The output is probed using a Tektronix highimpedance differential probe across the 953-Ω
resistor and referred to the amplifier output by adding
back the 0.42-dB because of the voltage divider on
the output.
From
50-W
Source
RF
RG
RIT
1 V/V
2 V/V
1 kΩ
1 kΩ
52.3 Ω
1 kΩ
487 Ω
53.6 Ω
5 V/V
10 V/V
1 kΩ
187 Ω
59.0 Ω
1 kΩ
86.6 Ω
69.8 Ω
1. Gain setting includes 50-Ω source impedance.
Components are chosen to achieve gain and 50-
VIN+
RG
Calibrated
Differential
Probe
Across
RIT
1 kW
VS+
RIT
24.9 W
PD
Open
Table 2. Gain Component Values for
Single-Ended Input(1)
Gain
Atten
THS452x
0.22 mF
VOCM
Installed to
Balance
Amplifier
VS-
49.9 W
RIT
RG
24.9 W
953 W
Measure with
Differential
Probe
Across ROT
Open
0.22 mF
1 kW
Figure 27. Frequency Response Test Circuit
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Distortion
The circuit shown in Figure 28 is used to measure
harmonic and intermodulation distortion of the
amplifier.
An HP signal generator is used as the signal source
and the output is measured with a Rhode and
Schwarz spectrum analyzer. The output impedance
of the HP signal generator is ac-coupled and is 50 Ω.
RIT and RG are chosen to impedance match to 50 Ω
and maintain the proper gain. To balance the
amplifier, a 0.22-μF capacitor and 49.9-Ω resistor to
ground are inserted across RIT on the alternate input.
A low-pass filter is inserted in series with the input to
reduce harmonics generated at the signal source.
The level of the fundamental is measured and then a
high-pass filter is inserted at the output to reduce the
fundamental so it does not generate distortion in the
input of the spectrum analyzer.
Slew Rate, Transient Response, Settling
Time, Output Impedance, Overdrive, Output
Voltage, and Turn-On/Turn-Off Time
The circuit shown in Figure 29 is used to measure
slew rate, transient response, settling time, output
impedance, overdrive recovery, output voltage swing,
and ampliifer turn-on/turn-off time. Turn-on and turnoff time are measured with the same circuit modified
for 50-Ω input impedance on the PD input by
replacing the 0.22-μF capacitor with a 49.9-Ω
resistor. For output impedance, the signal is injected
at VOUT with VIN open; the drop across the 2x 49.9-Ω
resistors is then used to calculate the impedance
seen looking into the amplifier output.
From
50-W
Source
VIN+
RG
RIT
49.9 W
PD
Open
The transformer used in the output to convert the
signal from differential to single-ended is an
ADT1–1WT. It limits the frequency response of the
circuit so that measurements cannot be made below
approximately 1 MHz.
From
50-W
Source
VIN+
RG
RF
VS+
RIT
VOUT
RO
PD
Open
THS452x
0.22 mF
RO
VOCM
Installed to
Balance
Amplifier
VS0.22 mF
RIT
RG
1:1
ROT
To 50-W
Test
Equipment
1 kW
VS+
THS452x
0.22 mF
VOCM
Installed to
Balance
Amplifier
VS-
49.9 W
RIT
RG
49.9 W
VOUT-
VOUT+
To Oscilloscope
with 50-W Input
Open
0.22 mF
1 kW
Figure 29. Slew Rate, Transient Response,
Settling Time, Output Impedance, Overdrive
Recovery, VOUT Swing, and Turn-On/Turn-Off Test
Circuit
Open
0.22 mF
RF
49.9 W
Figure 28. Distortion Test Circuit
16
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Common-Mode and Power-Supply Rejection
VOCM Input
The circuit shown in Figure 30 is used to measure the
CMRR. The signal from the network analyzer is
applied common-mode to the input. Figure 31 is used
to measure the PSRR of VS+ and VS–. The power
supply under test is applied to the network analyzer
dc offset input. For both CMRR and PSRR, the output
is probed using a Tektronix high-impedance
differential probe across the 953-Ω resistor and
referred to the amplifier output by adding back the
0.42-dB as a result of the voltage divider on the
output. For these tests, the resistors are matched for
best results.
The circuit illustrated in Figure 32 is used to measure
the frequency response and input impedance of the
VOCM input. Frequency response is measured using a
Tektronix high-impedance differential probe, with
RCM = 0 Ω at the common point of VOUT+ and VOUT–,
formed at the summing junction of the two matched
499-Ω resistors, with respect to ground. The input
impedance is measured using a Tektronix highimpedance differential probe at the VOCM input with
RCM = 10 kΩ and the drop across the 10-kΩ resistor
is used to calculate the impedance seen looking into
the amplifier VOCM input.
From
Network
Analyzer
VIN+
1 kW
1 kW
VS+
24.9 W
PD
Open
Calibrated
Differential
Probe
THS452x
52.3 W
953 W
24.9 W
0.22 mF
VOCM
Measure with
Differential
Probe
Open
0.22 mF
VS-
The circuit shown in Figure 33 measures the transient
response and slew rate of the VOCM input. A 1-V step
input is applied to the VOCM input and the output is
measured using a 50-Ω oscilloscope input referenced
back to the amplifier output.
1 kW
1 kW
Open
VS+
49.9 W
1 kW
1 kW
499 W
Figure 30. CMRR Test Circuit
PD
Open
THS452x
0.22 mF
499 W
RCM
VOCM
VS
Power
Supply
Open
1 kW
49.9 W
Network
Analyzer
1 kW
1 kW
Open
Calibrated Differential
Probe
Across
VS+ and GND
1 kW
Calibrated
Measurement Differential
Probe
Point for ZIN
Across
49.9 W
Resistor
From
Network
Analyzer
49.9 W
Figure 32. VOCM Input Test Circuit
VS+
52.3 W
1 kW
24.9 W
Open
Measurement
Point for Bandwidth
PD
THS452x
0.22 mF
VOCM
VS-
24.9 W
1 kW
Open
VS+
Measure with
Differential
953 W
Probe
Across ROT
Open
0.22 mF
52.3 W
499 W
PD
Open
THS452x
0.22 mF
To Oscilloscope
50-W Input
499 W
49.9 W
VOCM
Open
1 kW
52.3 W
VS-
1 kW
1 kW
52.3 W
Figure 31. PSRR Test Circuit
space
Step
Input
Open
1 kW
49.9 W
Figure 33. VOCM Transient Response and Slew
Rate Test Circuit
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APPLICATION INFORMATION
The following circuits show application information for
the
THS4521.
For
simplicity,
power-supply
decoupling capacitors are not shown in these
diagrams;
see
the
EVM
and
Layout
Recommendations section for suggested guidelines.
For more details on the use and operation of fully
differential op amps, refer to the Application Report
Fully-Differential Amplifiers (SLOA054), available for
download from the TI web site at www.ti.com.
Single-Ended
Input
VS+
Differential
Input
Differential
Output
RG
VOUT-
VIN+
THS452x
VIN-
VOUT+
RG
VS-
VOUT+
VS-
RF
Figure 35. Single-Ended Input to Differential
Output Amplifier
The input common-mode voltage of a fully-differential
op amp is the voltage at the + and – input pins of the
device.
It is important to not violate the input common-mode
voltage range (VICR) of the op amp. Assuming the op
amp is in linear operation, the voltage across the
input pins is only a few millivolts at most. Therefore,
finding the voltage at one input pin determines the
input common-mode voltage of the op amp.
Treating the negative input as a summing node, the
voltage is given by Equation 1:
RF
Figure 34. Differential Input to Differential Output
Amplifier
Single-Ended Input to Differential Output
Amplifier
The THS4521 can also amplify and convert singleended input signals to differential output signals.
Figure 35 illustrates a basic block diagram of the
circuit (VOCM and PD inputs not shown). The gain of
the circuit is again set by RF divided by RG.
18
THS452x
Input Common-Mode Voltage Range
RF
VS+
Differential
Output
VOUT-
RG
Differential Input to Differential Output
Amplifier
The THS4521 is fully-differential operational
amplifiers that can be used to amplify differential
input signals to differential output signals. Figure 34
shows a basic block diagram of the circuit (VOCM and
PD inputs not shown). The gain of the circuit is set by
RF divided by RG.
RF
RG
VOUT+ ´
RF
RG
+ VIN- ´
R G + RF
RG + RF
(1)
To determine the VICR of the op amp, the voltage at
the negative input is evaluated at the extremes of
VOUT+. As the gain of the op amp increases, the input
common-mode voltage becomes closer and closer to
the input common-mode voltage of the source.
Setting the Output Common-Mode Voltage
The output common-model voltage is set by the
voltage at the VOCM pin. The internal common-mode
control circuit maintains the output common-mode
voltage within 5-mV offset (typ) from the set voltage.
If left unconnected, the common-mode set point is set
to midsupply by internal circuitry, which may be
overdriven from an external source.
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Figure 36 represents the VOCM input. The internal
VOCM circuit has typically 23 MHz of –3 dB bandwidth,
which is required for best performance, but it is
intended to be a dc bias input pin. A 0.22-μF bypass
capacitor is recommended on this pin to reduce
noise. The external current required to overdrive the
internal resistor divider is given approximately by the
formula in Equation 2:
2VOCM - (VS+ - VS-)
IEXT =
50 kW
Single-Supply Operation
To facilitate testing with common lab equipment, the
THS4521EVM allows for split-supply operation; most
of the characterization data presented in this data
sheet is measured using split-supply power inputs.
The device can easily be used with a single-supply
power input without degrading performance.
Figure 37 shows a dc-coupled single-supply circuit
with single-ended inputs. This circuit can also be
applied to differential input sources.
where:
•
VOCM is the voltage applied to the VOCM pin
(2)
VIN+
RG
RF
VS+
VS+
RIT
RO
100 kW
IEXT
To internal
VOCM circuit
VOUT-
PD
PD Control
VOCM
THS452x
0.22 mF
VOUT+
VS-
100 kW
Optional;
installed to
balance
impedance seen
at VIN+
VS-
RO
VOCM
VOCM Control
0.22 mF
RIT
RG
RF
Figure 36. VOCM Input Circuit
Typical Performance Variation with Supply
Voltage
The THS4521 provides excellent performance across
the specified power-supply range of 2.5 V to 3.3 V
with only minor variations. The input and output
voltage compliance ranges track with the power
supply in nearly a 1:1 correlation. Other changes can
be observed in slew rate, output current drive, openloop gain, bandwidth, and distortion.
Figure 37. THS4521 DC-Coupled Single-Supply
with Single-Ended Inputs
The input common-mode voltage range of the
THS4521 is designed to include the negative supply
voltage. In the circuit shown in Figure 37, the signal
source is referenced to ground. VOCM is set by an
external control source or, if left unconnected, the
internal circuit defaults to midsupply. Together with
the input impedance of the amplifier circuit, RIT
provides input termination, which is also referenced to
ground.
Note that RIT and optional matching components are
added to the alternate input to balance the
impedance at signal input.
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Copyright © 2011–2012, Texas Instruments Incorporated
Product Folder Link(s): THS4521-HT
19
THS4521-HT
SBOS548D – APRIL 2011 – REVISED MAY 2012
www.ti.com
Low-Power Applications and the Effects of
Resistor Values on Bandwidth
For low-power operation, it may be necessary to
increase the gain setting resistors values to limit
current consumption and not load the source. Using
larger value resistors lowers the bandwidth of the
THS4521 as a result of the interactions between the
resistors, the device parasitic capacitance, and
printed circuit board (PCB) parasitic capacitance.
6.00E+00
100 kW
Signal Gain (dB)
10 kW
1 kW
1.00E+00
-4.00E+00
-9.00E+00
Driving Capacitive Loads
The THS4521 is designed for a nominal capacitive
load of 1 pF on each output to ground. When driving
capacitive loads greater than 1 pF, it is recommended
to use small resistors (RO) in series with the output,
placed as close to the device as possible. Without
RO, capacitance on the output interacts with the
output impedance of the amplifier and causes phase
shift in the loop gain of the amplifier that reduces the
phase margin. This reduction in phase margin results
in
frequency
response
peaking;
overshoot,
undershoot, and/or ringing when a step or squarewave signal is applied; and may lead to instability or
oscillation. Inserting RO isolates the phase shift from
the loop gain path and restores the phase margin, but
it also limits bandwidth.
-1.40E+01
-1.90E+01
-2.40E+01
100000
1000000
10000000
100000000
Frequency (Hz)
1000000000
Figure 38. THS4521 Frequency Response with
Various Gain Setting and Load Resistor Values
20
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Copyright © 2011–2012, Texas Instruments Incorporated
Product Folder Link(s): THS4521-HT
THS4521-HT
www.ti.com
SBOS548D – APRIL 2011 – REVISED MAY 2012
LAYOUT RECOMMENDATIONS
It is recommended to follow the layout of the external components near to the amplifier, ground plane
construction, and power routing as closely as possible. Follow these general guidelines:
1. Signal routing should be direct and as short as possible into and out of the op amp circuit.
2. The feedback path should be short and direct.
3. Ground or power planes should be removed from directly under the amplifier input and output pins.
4. An output resistor is recommended in each output lead, placed as near to the output pins as possible.
5. Two 0.1-μF power-supply decoupling capacitors should be placed as near to the power-supply pins as
possible.
6. Two 10-μF power-supply decoupling capacitors should be placed within 1 inch of the device and can be
shared among multple analog devices.
7. A 0.22-μF capacitor should be placed between the VOCM input pin and ground near to the pin. This capacitor
limits noise coupled into the pin.
8. The PD pin uses TTL logic levels; a bypass capacitor is not necessary if actively driven, but can be used for
robustness in noisy environments whether driven or not.
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Copyright © 2011–2012, Texas Instruments Incorporated
Product Folder Link(s): THS4521-HT
21
PACKAGE OPTION ADDENDUM
www.ti.com
4-Feb-2021
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
THS4521HD
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-55 to 175
T4521H
THS4521SHKJ
ACTIVE
CFP
HKJ
8
1
RoHS & Green
Call TI
N / A for Pkg Type
-55 to 210
THS4521
HKJ
THS4521SHKQ
ACTIVE
CFP
HKQ
8
1
RoHS & Green
AU
N / A for Pkg Type
-55 to 210
THS4521S
HKQ
THS4521SKGD1
ACTIVE
XCEPT
KGD
0
324
RoHS & Green
Call TI
N / A for Pkg Type
-55 to 210
(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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