OPA4353 [BB]
High-Speed, Single-Supply, Rail-to-Rail OPERATIONAL AMPLIFIERS MicroAmplifier ⑩ Series; 高速，单电源，轨至轨运算放大器MicroAmplifier ⑩系列
| 型号： | OPA4353 |
| 厂家： | 
BURR-BROWN CORPORATION |
| 描述： | High-Speed, Single-Supply, Rail-to-Rail OPERATIONAL AMPLIFIERS MicroAmplifier ⑩ Series |
| 文件： | 总11页 (文件大小：196K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
OPA2353
OPA353
OPA2353
OPA4353
OPA4353
O
P
A4353
For most current data sheet and other product
information, visit www.burr-brown.com
High-Speed, Single-Supply, Rail-to-Rail
OPERATIONAL AMPLIFIERS
™
MicroAmplifier Series
APPLICATIONS
FEATURES
● CELL PHONE PA CONTROL LOOPS
● DRIVING A/D CONVERTERS
● VIDEO PROCESSING
● DATA ACQUISITION
● PROCESS CONTROL
● AUDIO PROCESSING
● COMMUNICATIONS
● RAIL-TO-RAIL INPUT
● RAIL-TO-RAIL OUTPUT (within 10mV)
● WIDE BANDWIDTH: 44MHz
● HIGH SLEW RATE: 22V/µs
● LOW NOISE: 5nV/√Hz
● LOW THD+NOISE: 0.0006%
● UNITY-GAIN STABLE
● ACTIVE FILTERS
● MicroSIZE PACKAGES
● TEST EQUIPMENT
● SINGLE, DUAL, AND QUAD
DESCRIPTION
extends 300mV beyond the supply rails. Output voltage
swing is to within 10mV of the supply rails with a 10kΩ
load. Dual and quad designs feature completely indepen-
dent circuitry for lowest crosstalk and freedom from
interaction.
OPA353 series rail-to-rail CMOS operational amplifi-
ers are designed for low cost, miniature applications.
They are optimized for low voltage, single-supply op-
eration. Rail-to-rail input/output, low noise (5nV/√Hz),
and high speed operation (44MHz, 22V/µs) make them
ideal for driving sampling analog-to-digital converters.
They are also well suited for cell phone PA control
loops and video processing (75Ω drive capability) as
well as audio and general purpose applications. Single,
dual, and quad versions have identical specifications
for design flexibility.
The single (OPA353) packages are the tiny 5-lead SOT-
23-5 surface mount and SO-8 surface mount. The dual
(OPA2353) comes in the miniature MSOP-8 surface
mount and SO-8 surface mount. The quad (OPA4353)
packages are the space-saving SSOP-16 surface mount
and SO-14 surface mount. All are specified from –40°C
to +85°C and operate from –55°C to +125°C.
The OPA353 series operates on a single supply as low as
2.5V with an input common-mode voltage range that
OPA4353
SPICE Model available at www.burr-brown.com
OPA353
Out A
–In A
+In A
+V
1
2
3
4
5
6
7
8
16 Out D
15 –In D
14 +In D
13 –V
NC
NC
–In
+In
V–
1
2
3
4
8
7
6
5
A
B
D
C
V+
Output
NC
OPA2353
+In B
–In B
Out B
NC
12 +In C
11 –In C
10 Out C
OPA353
Out A
1
2
3
4
8
7
6
5
V+
A
SO-8
–In A
+In A
V–
Out B
–In B
+In B
Out
V–
1
2
3
5
4
V+
B
9
NC
+In
–In
SSOP-16
(SO-14 package not shown)
SO-8, MSOP-8
SOT-23-5
International Airport Industrial Park
•
Mailing Address: PO Box 11400, Tucson, AZ 85734
•
Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706
• Tel: (520) 746-1111
Twx: 910-952-1111 Internet: http://www.burr-brown.com/
•
•
Cable: BBRCORP Telex: 066-6491
•
•
FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
•
© 1998 Burr-Brown Corporation
PDS-1479B
Printed in U.S.A. March, 1999
SPECIFICATIONS: VS = 2.7V to 5.5V
At TA = +25°C, RL = 1kΩ connected to VS/2 and VOUT = VS /2, unless otherwise noted.
Boldface limits apply over the specified temperature range, TA = –40°C to +85°C. VS = 5V.
OPA353NA, UA
OPA2353EA, UA
OPA4353EA, UA
PARAMETER
CONDITION
MIN
TYP(1)
MAX
UNITS
OFFSET VOLTAGE
Input Offset Voltage
TA = –40°C to +85°C
VOS
VS = 5V
±3
±8
±10
mV
mV
vs Temperature
vs Power Supply Rejection Ratio
TA = –40°C to +85°C
TA = –40°C to +85°C
VS = 2.7V to 5.5V, VCM = 0V
VS = 2.7V to 5.5V, VCM = 0V
dc
±5
40
µV/°C
µV/V
µV/V
µV/V
PSRR
150
175
Channel Separation (dual, quad)
0.15
INPUT BIAS CURRENT
Input Bias Current
IB
±0.5
See Typical Curve
±0.5
±10
±10
pA
pA
T
A = –40°C to +85°C
Input Offset Current
IOS
NOISE
Input Voltage Noise, f = 100Hz to 400kHz
Input Voltage Noise Density, f = 10kHz
f = 100kHz
4
7
5
4
µVrms
nV/√Hz
nV/√Hz
fA/√Hz
en
in
Current Noise Density, f = 10kHz
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
Common-Mode Rejection Ratio
VCM
CMRR
–0.1
76
60
(V+) + 0.1
V
–0.1V < VCM < (V+) – 2.4V
VS = 5V, –0.1V < VCM < 5.1V
VS = 5V, –0.1V < VCM < 5.1V
86
74
dB
dB
dB
TA = –40°C to +85°C
58
INPUT IMPEDANCE
Differential
Common-Mode
1013 || 2.5
1013 || 6.5
Ω || pF
Ω || pF
OPEN-LOOP GAIN
Open-Loop Voltage Gain
TA = –40°C to +85°C
AOL
RL = 10kΩ, 50mV < VO < (V+) – 50mV
RL = 10kΩ, 50mV < VO < (V+) – 50mV
RL = 1kΩ, 200mV < VO < (V+) – 200mV
RL = 1kΩ, 200mV < VO < (V+) – 200mV
100
100
100
100
122
120
dB
dB
dB
dB
TA = –40°C to +85°C
FREQUENCY RESPONSE
Gain-Bandwidth Product
Slew Rate
Settling Time, 0.1%
0.01%
CL = 100pF
G = 1
G = 1
G = ±1, 2V Step
G = ±1, 2V Step
GBW
SR
44
22
0.22
0.5
MHz
V/µs
µs
µs
Overload Recovery Time
Total Harmonic Distortion + Noise
Differential Gain Error
Differential Phase Error
VIN • G = VS
0.1
µs
%
%
deg
THD+N
VOUT
RL = 600Ω, VO = 2.5Vp-p(2), G = 1, f = 1kHz
G = 2, RL = 600Ω, VO = 1.4V(3)
G = 2, RL = 600Ω, VO = 1.4V(3)
0.0006
0.17
0.17
OUTPUT
Voltage Output Swing from Rail(4)
TA = –40°C to +85°C
RL = 10kΩ, AOL ≥ 100dB
RL = 10kΩ, AOL ≥ 100dB
RL = 1kΩ, AOL ≥ 100dB
RL = 1kΩ, AOL ≥ 100dB
10
25
50
50
200
200
mV
mV
mV
mV
mA
mA
TA = –40°C to +85°C
Output Current
Short-Circuit Current
Capacitive Load Drive
IOUT
ISC
CLOAD
±40(5)
±80
See Typical Curve
POWER SUPPLY
Operating Voltage Range
Minimum Operating Voltage
Quiescent Current (per amplifier)
TA = –40°C to +85°C
VS
IQ
TA = –40°C to +85°C
2.7
5.5
V
V
mA
mA
2.5
5.2
IO = 0
IO = 0
8
9
TEMPERATURE RANGE
Specified Range
Operating Range
–40
–55
–55
+85
+125
+125
°C
°C
°C
Storage Range
Thermal Resistance
SOT-23-5
MSOP-8 Surface Mount
SO-8 Surface Mount
SSOP-16 Surface Mount
SO-14 Surface Mount
θJA
200
150
150
100
100
°C/W
°C/W
°C/W
°C/W
°C/W
NOTES: (1) VS = +5V. (2) VOUT = 0.25V to 2.75V. (3) NTSC signal generator used. See Figure 6 for test circuit. (4) Output voltage swings are measured between
the output and power supply rails. (5) See typical performance curve, “Output Voltage Swing vs Output Swing.”
®
2
OPA353, 2353, 4353
PIN CONFIGURATION
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
Top View
SO-14
OPA4353
Out A
–In A
+In A
V+
1
2
3
4
5
6
7
14 Out D
13 –In D
12 +In D
11 V–
A
B
D
C
ESD damage can range from subtle performance degrada-
tion 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.
+In B
–In B
Out B
10 +In C
9
8
–In C
Out C
ABSOLUTE MAXIMUM RATINGS(1)
Supply Voltage ................................................................................... 5.5V
Signal Input Terminals, Voltage(2) .................. (V–) – 0.3V to (V+) + 0.3V
Current(2) .................................................... 10mA
Output Short-Circuit(3) .............................................................. Continuous
Operating Temperature ..................................................–55°C to +125°C
Storage Temperature .....................................................–55°C to +125°C
Junction Temperature ...................................................................... 150°C
Lead Temperature (soldering, 10s)................................................. 300°C
NOTES: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may de-
grade device reliability. (2) Input terminals are diode-clamped to the power
supply rails. Input signals that can swing more than 0.3V beyond the supply
rails should be current-limited to 10mA or less. (3) Short circuit to ground,
one amplifier per package.
PACKAGE/ORDERING INFORMATION
PACKAGE
DRAWING
NUMBER(1)
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER(2)
TRANSPORT
MEDIA
PRODUCT
PACKAGE
Single
OPA353NA
5-Lead SOT-23-5
331
"
182
"
–40°C to +85°C
D53
OPA353NA/250
OPA353NA/3K
OPA353UA
Tape and Reel
Tape and Reel
Rails
"
"
"
"
OPA353UA
SO-8 Surface Mount
–40°C to +85°C
OPA353UA
"
"
"
"
OPA353UA/2K5
Tape and Reel
Dual
OPA2353EA
MSOP-8 Surface Mount
337
"
182
"
–40°C to +85°C
E53
"
OPA2353UA
OPA2353EA/250
OPA2353EA/2K5
OPA2353UA
Tape and Reel
Tape and Reel
Rails
"
"
"
OPA2353UA
SO-8 Surface Mount
–40°C to +85°C
"
"
"
"
OPA2353UA/2K5
Tape and Reel
Quad
OPA4353EA
SSOP-16 Surface Mount
322
"
235
"
–40°C to +85°C
OPA4353EA
OPA4353EA/250
OPA4353EA/2K5
OPA4353UA
Tape and Reel
Tape and Reel
Rails
"
"
"
"
OPA4353UA
SO-14 Surface Mount
–40°C to +85°C
OPA4353UA
"
"
"
"
OPA4353UA/2K5
Tape and Reel
NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) Models with a slash (/) are
available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of “OPA2353EA/2K5” will get a single
2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility
for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or
licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support
devices and/or systems.
®
3
OPA353, 2353, 4353
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = +5V, and RL = 1kΩ connected to VS/2, unless otherwise noted.
POWER SUPPLY AND COMMON-MODE
REJECTION RATIO vs FREQUENCY
OPEN-LOOP GAIN/PHASE vs FREQUENCY
160
140
120
100
80
0
100
90
80
70
60
50
40
30
20
10
0
PSRR
–45
–90
–135
–180
CMRR
(VS = +5V
φ
VCM = –0.1V to 5.1V)
60
G
40
20
0
0.1
1
10
100
1k
10k 100k
1M
10M 100M
10
100
1k
10k
100k
1M
10M
Frequency (Hz)
Frequency (Hz)
INPUT VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY vs FREQUENCY
CHANNEL SEPARATION vs FREQUENCY
10k
1k
100k
10k
1k
140
130
120
110
100
90
Current Noise
100
10
Voltage Noise
100
10
80
1
Dual and Quad
Versions
70
0.1
1
60
10
100
1k
10k
100k
1M
10M
10
100
1k
10k
100k
1M
10M
Frequency (Hz)
Frequency (Hz)
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
HARMONIC DISTORTION + NOISE vs FREQUENCY
1
1
0.1
G = 1
VO = 2.5Vp-p
RL = 600Ω
(–40dBc)
RL = 600Ω
0.1
(–60dBc)
G = 100, 3Vp-p (VO = 1V to 4V)
G = 10, 3Vp-p (VO = 1V to 4V)
0.01
(–80dBc)
0.01
G = 1, 3Vp-p (VO = 1V to 4V)
Input goes through transition region
0.001
(–100dBc)
0.001
0.0001
3rd Harmonic
2nd Harmonic
G = 1, 2.5Vp-p (VO = 0.25V to 2.75V)
Input does NOT go through transition region
0.0001
(–120dBc)
1k
10k
100k
Frequency (Hz)
1M
10
100
1k
10k
100k
Frequency (Hz)
®
4
OPA353, 2353, 4353
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = +5V, and RL = 1kΩ connected to VS/2, unless otherwise noted.
OPEN-LOOP GAIN vs TEMPERATURE
DIFFERENTIAL GAIN/PHASE vs RESISTIVE LOAD
130
125
120
115
110
0.5
0.4
0.3
0.2
0.1
0
G = 2
V
O = 1.4V
Phase
NTSC Signal Generator
See Figure 6 for test circuit.
RL = 1kΩ
RL = 10kΩ
Gain
RL = 600Ω
–75
–50 –25
0
25
50
75
100 125
0
100 200 300 400 500 600 700 800 900 1000
Temperature (°C)
Resistive Load (Ω)
COMMON-MODE AND POWER SUPPLY
REJECTION RATIO vs TEMPERATURE
SLEW RATE vs TEMPERATURE
90
80
70
60
50
110
40
35
30
25
20
15
10
5
CMRR, VS = 5V
(VCM = –0.1V to +5.1V)
100
90
Negative Slew Rate
Positive Slew Rate
PSRR
80
70
0
–75
–50
–25
0
25
50
75
100
125
–75
–50
–25
0
25
50
75
100
125
Temperature (°C)
Temperature (°C)
QUIESCENT CURRENT AND
SHORT-CIRCUIT CURRENT vs TEMPERATURE
QUIESCENT CURRENT vs SUPPLY VOLTAGE
Per Amplifier
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
100
90
80
70
60
50
40
30
6.0
5.5
5.0
4.5
4.0
3.5
3.0
+ISC
–ISC
IQ
–75
–50
–25
0
25
50
75
100
125
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Temperature (°C)
Supply Voltage (V)
®
5
OPA353, 2353, 4353
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = +5V, and RL = 1kΩ connected to VS/2, unless otherwise noted.
INPUT BIAS CURRENT
INPUT BIAS CURRENT vs TEMPERATURE
vs INPUT COMMON-MODE VOLTAGE
1k
100
10
1.5
1.0
0.5
1
0.0
0.1
–0.5
–75
–50
–25
0
25
50
75
100
125
–0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
Temperature (°C)
Common-Mode Voltage (V)
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
CLOSED-LOOP OUTPUT IMPEDANCE vs FREQUENCY
6
100
10
VS = 5.5V
Maximum output
voltage without
slew rate-induced
distortion.
5
4
3
2
1
0
1
G = 100
VS = 2.7V
0.1
G = 10
G = 1
0.01
0.001
0.0001
1
10
100
1k
10k 100k
1M
10M 100M
100k
1M
10M
100M
Frequency (Hz)
Frequency (Hz)
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
OPEN-LOOP GAIN vs OUTPUT VOLTAGE SWING
IOUT = 250µA
IOUT = 2.5mA
V+
(V+)–1
(V+)–2
(V–)+2
(V–)+1
(V–)
140
130
120
110
100
90
+25°C
–55°C
+125°C
Depending on circuit configuration
(including closed-loop gain) performance
may be degraded in shaded region.
IOUT = 4.2mA
+25°C
–55°C
80
+125°C
70
60
0
±10
±20
Output Current (mA)
±30
±40
0
20
40
60
80 100 120 140 160 180 200
Output Voltage Swing from Supply Rails (mV)
®
6
OPA353, 2353, 4353
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = +5V, and RL = 1kΩ connected to VS/2, unless otherwise noted.
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
OFFSET VOLTAGE PRODUCTION DISTRIBUTION
35
30
25
20
15
10
5
25
20
15
10
5
Typical production
distribution of
packaged units.
Typical production
distribution of
packaged units.
0
0
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
–8 –7 –6 –5
4
–3 –2 –1
0
1
2
3
4
5
6
7 8
Offset Voltage Drift (µV/°C)
Offset Voltage (mV)
SETTLING TIME vs CLOSED-LOOP GAIN
SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE
10
80
70
60
50
40
30
20
10
0
G = 1
0.01%
G = –1
1
G = ±10
0.1%
0.1
10
100
1k
10k
100k
1M
±1
±10
±100
Load Capacitance (pF)
Closed-Loop Gain (V/V)
LARGE-SIGNAL STEP RESPONSE
CL = 100pF
SMALL-SIGNAL STEP RESPONSE
CL = 100pF
200ns/div
100ns/div
®
7
OPA353, 2353, 4353
the OPA353 in unity-gain configuration. Operation is
from a single +5V supply with a 1kΩ load connected to
VS /2. The input is a 5Vp-p sinusoid. Output voltage is
approximately 4.95Vp-p.
APPLICATIONS INFORMATION
OPA353 series op amps are fabricated on a state-of-the-art
0.6 micron CMOS process. They are unity-gain stable and
suitable for a wide range of general purpose applications.
Rail-to-rail input/output make them ideal for driving sam-
pling A/D converters. They are well suited for controlling
the output power in cell phones. These applications often
require high speed and low noise. In addition, the OPA353
series offers a low cost solution for general purpose and
consumer video applications (75Ω drive capability).
Power supply pins should be bypassed with 0.01µF ceramic
capacitors.
OPERATING VOLTAGE
OPA353 series op amps are fully specified from +2.7V to
+5.5V. However, supply voltage may range from +2.5V to
+5.5V. Parameters are guaranteed over the specified supply
range—a unique feature of the OPA353 series. In addition,
many specifications apply from –40°C to +85°C. Most
behavior remains virtually unchanged throughout the full
operating voltage range. Parameters which vary signifi-
cantly with operating voltages or temperature are shown in
the typical performance curves.
Excellent ac performance makes the OPA353 series well
suited for audio applications. Their bandwidth, slew rate,
low noise (5nV/√Hz), low THD (0.0006%), and small pack-
age options are ideal for these applications. The class AB
output stage is capable of driving 600Ω loads connected to
any point between V+ and ground.
Rail-to-rail input and output swing significantly increases
dynamic range, especially in low voltage supply applica-
tions. Figure 1 shows the input and output waveforms for
RAIL-TO-RAIL INPUT
The guaranteed input common-mode voltage range of the
OPA353 series extends 100mV beyond the supply rails. This
is achieved with a complementary input stage—an
N-channel input differential pair in parallel with a P-channel
differential pair (see Figure 2). The N-channel pair is active
for input voltages close to the positive rail, typically
(V+) – 1.8V to 100mV above the positive supply, while the
P-channel pair is on for inputs from 100mV below the
negative supply to approximately (V+) – 1.8V. There is a
small transition region, typically (V+) – 2V to (V+) – 1.6V, in
which both pairs are on. This 400mV transition region can
vary ±400mV with process variation. Thus, the transition
region (both input stages on) can range from (V+) – 2.4V to
(V+) – 2.0V on the low end, up to (V+) – 1.6V to (V+) – 1.2V
on the high end.
VS = +5, G = +1, RL = 1kΩ
5V
VIN
0
5V
VOUT
0
FIGURE 1. Rail-to-Rail Input and Output.
V+
Reference
Current
VIN+
VIN–
VBIAS1
Class AB
Control
VO
Circuitry
VBIAS2
V–
(Ground)
FIGURE 2. Simplified Schematic.
®
8
OPA353, 2353, 4353
A double-folded cascode adds the signal from the two input
pairs and presents a differential signal to the class AB output
stage. Normally, input bias current is approximately 500fA.
However, large inputs (greater than 300mV beyond the
supply rails) can turn on the OPA353’s input protection
diodes, causing excessive current to flow in or out of the
input pins. Momentary voltages greater than 300mV beyond
the power supply can be tolerated if the current on the input
pins is limited to 10mA. This is easily accomplished with an
input resistor as shown in Figure 3. Many input signals are
inherently current-limited to less than 10mA, therefore, a
limiting resistor is not required.
FEEDBACK CAPACITOR IMPROVES RESPONSE
For optimum settling time and stability with high-imped-
ance feedback networks, it may be necessary to add a
feedback capacitor across the feedback resistor, RF, as
shown in Figure 4. This capacitor compensates for the zero
created by the feedback network impedance and the
OPA353’s input capacitance (and any parasitic layout
capacitance). The effect becomes more significant with
higher impedance networks.
CF
RIN
RF
V+
VIN
V+
IOVERLOAD
10mA max
CIN
OPA353
CIN
VOUT
OPAx353
RIN • CIN = RF • CF
VIN
VOUT
5kΩ
CL
Where CIN is equal to the OPA353’s input
capacitance (approximately 9pF) plus any
parastic layout capacitance.
FIGURE 3. Input Current Protection for Voltages Exceeding
the Supply Voltage.
RAIL-TO-RAIL OUTPUT
FIGURE 4. Feedback Capacitor Improves Dynamic Perfor-
mance.
A class AB output stage with common-source transistors is
used to achieve rail-to-rail output. For light resistive loads
(>10kΩ), the output voltage swing is typically ten millivolts
from the supply rails. With heavier resistive loads (600Ω to
10kΩ), the output can swing to within a few tens of milli-
volts from the supply rails and maintain high open-loop
gain. See the typical performance curves “Output Voltage
Swing vs Output Current” and “Open-Loop Gain vs Output
Voltage.”
It is suggested that a variable capacitor be used for the
feedback capacitor since input capacitance may vary be-
tween op amps and layout capacitance is difficult to
determine. For the circuit shown in Figure 4, the value of
the variable feedback capacitor should be chosen so that
the input resistance times the input capacitance of the
OPA353 (typically 9pF) plus the estimated parasitic layout
capacitance equals the feedback capacitor times the feed-
back resistor:
CAPACITIVE LOAD AND STABILITY
RIN • CIN = RF • CF
OPA353 series op amps can drive a wide range of capacitive
loads. However, all op amps under certain conditions may
become unstable. Op amp configuration, gain, and load
value are just a few of the factors to consider when determin-
ing stability. An op amp in unity gain configuration is the
most susceptible to the effects of capacitive load. The
capacitive load reacts with the op amp’s output impedance,
along with any additional load resistance, to create a pole in
the small-signal response which degrades the phase margin.
where CIN is equal to the OPA353’s input capacitance
(sum of differential and common-mode) plus the layout
capacitance. The capacitor can be varied until optimum
performance is obtained.
DRIVING A/D CONVERTERS
OPA353 series op amps are optimized for driving medium
speed (up to 500kHz) sampling A/D converters. However,
they also offer excellent performance for higher speed
converters. The OPA353 series provides an effective means
of buffering the A/D’s input capacitance and resulting
charge injection while providing signal gain. For applica-
tions requiring high accuracy, the OPA350 series is recom-
mended.
In unity gain, OPA353 series op amps perform well with
large capacitive loads. Increasing gain enhances the
amplifier’s ability to drive more capacitance. The typical
performance curve “Small-Signal Overshoot vs Capacitive
Load” shows performance with a 1kΩ resistive load. In-
creasing load resistance improves capacitive load drive ca-
pability.
®
9
OPA353, 2353, 4353
Figure 5 shows the OPA353 driving an ADS7861. The
ADS7861 is a dual, 12-bit, 500kHz sampling converter in
the small SSOP-24 package. When used with the miniature
package options of the OPA353 series, the combination is
ideal for space-limited and low power applications. For
further information consult the ADS7861 data sheet.
from becoming too high, which can cause stability prob-
lems when driving capacitive loads. As mentioned previ-
ously, the OPA353 has excellent capacitive load drive
capability for an op amp with its bandwidth.
VIDEO LINE DRIVER
Figure 6 shows a circuit for a single supply, G = 2 com-
posite video line driver. The synchronized outputs of a
composite video line driver extend below ground. As
shown, the input to the op amp should be ac-coupled and
shifted positively to provide adequate signal swing to
account for these negative signals in a single-supply con-
figuration.
OUTPUT IMPEDANCE
The low frequency open-loop output impedance of the
OPA353’s common-source output stage is approximately
1kΩ. When the op amp is connected with feedback, this
value is reduced significantly by the loop gain of the op
amp. For example, with 122dB of open-loop gain, the
output impedance is reduced in unity-gain to less than
0.001Ω. For each decade rise in the closed-loop gain, the
loop gain is reduced by the same amount which results in
a ten-fold increase in output impedance (see the typical
performance curve, “Output Impedance vs Frequency”).
The input is terminated with a 75Ω resistor and ac-coupled
with a 47µF capacitor to a voltage divider that provides the
dc bias point to the input. In Figure 6, this point is
approximately (V–) + 1.7V. Setting the optimal bias point
requires some understanding of the nature of composite
video signals. For best performance, one should be careful
to avoid the distortion caused by the transition region of
the OPA353’s complementary input stage. Refer to the
discussion of rail-to-rail input.
At higher frequencies, the output impedance will rise as
the open-loop gain of the op amp drops. However, at these
frequencies the output also becomes capacitive due to
parasitic capacitance. This prevents the output impedance
CB1
+5V
2kΩ
2kΩ
2
3
4
1/4
OPA4353
VIN B1
0.1µF
0.1µF
CB0
24
+VD
13
+VA
2kΩ
2kΩ
2
3
23
22
21
20
19
18
17
16
15
14
CH B1+
CH B1–
CH B0+
CH B0–
CH A1+
CH A1–
CH A0+
CH A0–
REFIN
Serial Data A
Serial Data B
BUSY
6
7
1/4
OPA4353
4
5
5
VIN B0
CLOCK
6
CA1
CS
Serial
Interface
ADS7861
7
RD
CONVST
A0
2kΩ
2kΩ
8
9
9
10
11
8
1/4
OPA4353
M0
10
VIN A1
REFOUT
M1
CA0
DGND
1
AGND
12
2kΩ
2kΩ
14
1/4
OPA4353
VIN A0
11
VIN = 0V to 2.45V for 0V to 4.9V output.
Choose CB1, CB0, CA1, CA0 to filter high frequency noise.
FIGURE 5. OPA4353 Driving Sampling A/D Converter.
®
10
OPA353, 2353, 4353
RG
RF
1kΩ
1kΩ
C4
0.1µF
+5V
C1
220µF
+
0.1µF
10µF
7
C5
1000µF
ROUT
Cable
6
C2
47µF
VOUT
OPA353
Video
In
RL
R1
75Ω
R2
5kΩ
4
+5V (pin 7)
R3
5kΩ
R4
5kΩ
C3
10µF
FIGURE 6. Single-Supply Video Line Driver.
+5V
50kΩ
(2.5V)
8
RG
REF1004-2.5
R1
100kΩ
R2
25kΩ
4
+5V
R3
R4
25kΩ
100kΩ
1/2
OPA2353
1/2
OPA2353
VOUT
RL
10kΩ
200kΩ
G = 5 +
RG
FIGURE 7. Two Op-Amp Instrumentation Amplifier With Improved High Frequency Common-Mode Rejection.
<1pF (prevents gain peaking)
R1
10.5kΩ
10MΩ
+V
+2.5V
λ
VO
OPA353
C1
C2
1830pF
270pF
VOUT
OPA353
VIN
RL
20kΩ
FIGURE 8. Transimpedance Amplifier.
R2
49.9kΩ
–2.5V
C1
4.7µF
+2.5V
FIGURE 10. 10kHz High-Pass Filter.
R1
2.74kΩ
R2
19.6kΩ
VOUT
OPA353
RL
VIN
20kΩ
C2
1nF
–2.5V
FIGURE 9. 10kHz Low-Pass Filter.
®
11
OPA353, 2353, 4353
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