OPA2604 Dual FET-Input, Low Distortion OPERATIONAL AMPLIFIER

®
OPA
OPA2604
260
OPA
4
260
4
www.burr-brown.com/databook/OPA2604.html
Dual FET-Input, Low Distortion
OPERATIONAL AMPLIFIER
FEATURES
APPLICATIONS
● LOW DISTORTION: 0.0003% at 1kHz
● LOW NOISE: 10nV/√Hz
● HIGH SLEW RATE: 25V/µs
● PROFESSIONAL AUDIO EQUIPMENT
● PCM DAC I/V CONVERTER
● SPECTRAL ANALYSIS EQUIPMENT
● WIDE GAIN-BANDWIDTH: 20MHz
● UNITY-GAIN STABLE
● ACTIVE FILTERS
● TRANSDUCER AMPLIFIER
● WIDE SUPPLY RANGE: VS = ±4.5 to ±24V
● DRIVES 600Ω LOADS
● DATA ACQUISITION
(8)
V+
DESCRIPTION
The OPA2604 is a dual, FET-input operational amplifier designed for enhanced AC performance. Very low
distortion, low noise and wide bandwidth provide
superior performance in high quality audio and other
applications requiring excellent dynamic performance.
New circuit techniques and special laser trimming of
dynamic circuit performance yield very low harmonic
distortion. The result is an op amp with exceptional
sound quality. The low-noise FET input of the
OPA2604 provides wide dynamic range, even with high
source impedance. Offset voltage is laser-trimmed to
minimize the need for interstage coupling capacitors.
(+)
(3, 5)
(–)
(2, 6)
Distortion
Rejection
Circuitry*
(1, 7)
VO
Output
Stage*
The OPA2604 is available in 8-pin plastic mini-DIP
and SO-8 surface-mount packages, specified for the
–25°C to +85°C temperature range.
(4)
V–
* Patents Granted:
#5053718, 5019789
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/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
®
© 1991 Burr-Brown Corporation
1
PDS-1069E
OPA2604
Printed in U.S.A. October, 1997
SPECIFICATIONS
ELECTRICAL
At TA = +25°C, VS = ±15V, unless otherwise noted.
OPA2604AP, AU
PARAMETER
CONDITION
OFFSET VOLTAGE
Input Offset Voltage
Average Drift
Power Supply Rejection
INPUT BIAS CURRENT(1)
Input Bias Current
Input Offset Current
MIN
TYP
MAX
UNITS
±5
70
±1
±8
80
mV
µV/°C
dB
VS = ±5 to ±24V
VCM = 0V
VCM = 0V
NOISE
Input Voltage Noise
Noise Density: f = 10Hz
f = 100Hz
f = 1kHz
f = 10kHz
Voltage Noise, BW = 20Hz to 20kHz
Input Bias Current Noise
Current Noise Density, f = 0.1Hz to 20kHz
INPUT VOLTAGE RANGE
Common-Mode Input Range
Common-Mode Rejection
VCM = ±12V
±12
80
INPUT IMPEDANCE
Differential
Common-Mode
OPEN-LOOP GAIN
Open-Loop Voltage Gain
FREQUENCY RESPONSE
Gain-Bandwidth Product
Slew Rate
Settling Time: 0.01%
0.1%
Total Harmonic Distortion + Noise (THD+N)
Channel Separation
OUTPUT
Voltage Output
Current Output
Short Circuit Current
Output Resistance, Open-Loop
POWER SUPPLY
Specified Operating Voltage
Operating Voltage Range
Current, Total Both Amplifiers
VO = ±10V, RL = 1kΩ
80
G = 100
20Vp-p, RL = 1kΩ
G = –1, 10V Step
15
G = 1, f = 1kHz
VO = 3.5Vrms, RL = 1kΩ
f = 1kHz, RL = 1kΩ
RL = 600Ω
VO = ±12V
±11
±4.5
IO = 0
TEMPERATURE RANGE
Specification
Storage
Thermal Resistance(2), θJA
100
±4
pA
pA
25
15
11
10
1.5
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
µVp-p
6
fA/√Hz
±13
100
V
dB
1012 || 8
1012 || 10
Ω || pF
Ω || pF
100
dB
20
25
1.5
1
0.0003
MHz
V/µs
µs
µs
%
142
dB
±12
±35
±40
25
V
mA
mA
Ω
±15
±10.5
–25
–40
±24
±12
+85
+125
90
V
V
mA
°C
°C
°C/W
NOTES: (1) Typical performance, measured fully warmed-up. (2) Soldered to circuit board—see text.
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.
®
OPA2604
2
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS(1)
Top View
Power Supply Voltage ....................................................................... ±25V
Input Voltage ............................................................. (V–)–1V to (V+)+1V
Output Short Circuit to Ground ............................................... Continuous
Operating Temperature ................................................. –40°C to +100°C
Storage Temperature ..................................................... –40°C to +125°C
Junction Temperature .................................................................... +150°C
Lead Temperature (soldering, 10s) AP ......................................... +300°C
Lead Temperature (soldering, 3s) AU .......................................... +260°C
DIP/SOIC
Output A
1
8
V+
–In A
2
7
Output B
+In A
3
6
–In B
V–
4
5
+In B
NOTE: (1) Stresses above these ratings may cause permanent damage.
ORDERING INFORMATION
PRODUCT
OPA2604AP
OPA2604AU
ELECTROSTATIC
DISCHARGE SENSITIVITY
PACKAGE
TEMP. RANGE
8-Pin Plastic DIP
SO-8 Surface-Mount
–25°C to +85°C
–25°C to +85°C
PACKAGING INFORMATION
Any 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.
PACKAGE DRAWING
PRODUCT
OPA2604AP
OPA2604AU
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 published specifications.
PACKAGE
NUMBER(1)
8-Pin Plastic DIP
SO-8 Surface-Mount
006
182
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
®
3
OPA2604
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = ±15V, unless otherwise noted.
TOTAL HARMONIC DISTORTION + NOISE
vs OUTPUT VOLTAGE
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
1
THD + N (%)
VO
G = 100V/V
0.01
See “Distortion Measurements”
for description of test method.
1kΩ
0.01
THD + N (%)
VO =
3.5Vrms
1kΩ
0.1
0.1
Measurement BW = 80kHz
See “Distortion Measurements” for description of
test method.
f = 1kHz
Measurement BW = 80kHz
0.001
G = 10V/V
0.001
G = 1V/V
0.0001
20
100
1k
10k
0.0001
0.1
20k
1
10
100
Frequency (Hz)
Output Voltage (Vp-p)
OPEN-LOOP GAIN/PHASE vs FREQUENCY
INPUT VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY vs FREQUENCY
1k
1k
0
120
–90
60
40
–135
G
20
100
10
10
–180
0
Current Noise
1
–20
10
100
1k
10k
100k
1M
1
10M
10
100
100
1nA
10
100
Input
Offset Current
1
10
0
25
50
75
100
Input
Bias Current
1nA
100
10
100
Input
Offset Current
10
–15
0.1
125
–10
–5
0
5
Common-Mode Voltage (V)
Ambient Temperature (°C)
®
OPA2604
Input Bias Current (pA)
1nA
Input Offset Current (pA)
Input
Bias Current
–25
1
1M
1nA
10nA
10nA
100nA
–50
100k
INPUT BIAS AND INPUT OFFSET CURRENT
vs INPUT COMMON-MODE VOLTAGE
INPUT BIAS AND INPUT OFFSET CURRENT
vs TEMPERATURE
1
–75
10k
Frequency (Hz)
Frequency (Hz)
10nA
1k
4
10
1
15
Input Offset Current (pA)
1
Input Bias Current (pA)
100
Voltage Noise
Current Noise (fA/ Hz)
φ
Voltage Noise (nV/ Hz)
Voltage Gain (dB)
–45
80
Phase Shift (Degrees)
100
TYPICAL PERFORMANCE CURVES
(CONT)
At TA = +25°C, VS = ±15V, unless otherwise noted.
COMMON-MODE REJECTION
vs COMMON-MODE VOLTAGE
INPUT BIAS CURRENT
vs TIME FROM POWER TURN-ON
120
1nA
Common-Mode Rejection (dB)
Input Bias Current (pA)
VS = ±24VDC
VS = ±15VDC
100
VS = ±5VDC
10
1
2
3
4
100
90
80
–15
1
0
110
5
–10
POWER SUPPLY AND COMMON-MODE
REJECTION vs FREQUENCY
0
5
10
15
AOL, PSR, AND CMR vs SUPPLY VOLTAGE
120
120
CMR
100
110
AOL, PSR, CMR (dB)
PSR, CMR (dB)
–5
Common-Mode Voltage (V)
Time After Power Turn-On (min)
80
–PSR
+PSR
60
40
CMR
100
AOL
90
80
20
PSR
0
10
70
100
1k
10k
100k
1M
10M
5
10
15
20
Frequency (Hz)
Supply Voltage (±VS)
GAIN-BANDWIDTH AND SLEW RATE
vs SUPPLY VOLTAGE
GAIN-BANDWIDTH AND SLEW RATE
vs TEMPERATURE
28
25
28
33
30
29
Slew Rate
20
25
16
21
12
5
10
15
20
24
25
20
20
Gain-Bandwidth
G = +100
16
15
12
17
25
–75
–50
–25
0
Slew Rate (V/µs)
Gain-Bandwidth
G = +100
Gain-Bandwidth (MHz)
24
Slew Rate (V/µs)
Gain-Bandwidth (MHz)
Slew Rate
25
50
75
100
10
125
Temperature (°C)
Supply Voltage (±VS)
®
5
OPA2604
TYPICAL PERFORMANCE CURVES
(CONT)
At TA = +25°C, VS = ±15V, unless otherwise noted.
SETTLING TIME vs CLOSED-LOOP GAIN
CHANNEL SEPARATION vs FREQUENCY
5
160
VO = 10V Step
RL = 1kΩ
CL = 50pF
RL = ∞
Channel Separation (dB)
Settling Time (µs)
4
3
0.01%
2
0.1%
1
140
RL = 1kΩ
120
100
0
VO =
20Vp-p
RL
A
B
Measured
Output
80
–1
–10
–100
–1000
10
100
1k
Closed-Loop Gain (V/V)
MAXIMUM OUTPUT VOLTAGE SWING vs FREQUENCY
14
Total for Both Op Amps
Supply Current (mA)
Output Voltage (Vp-p)
VS = ±15V
20
10
0
VS = ±15VDC
12
VS = ±24VDC
10
VS = ±5VDC
8
6
10k
100k
1M
10M
–75
Frequency (Hz)
Output Voltage (mV)
Output Voltage (V)
+10
FPO
Bleed to edge
0
5
0
25
50
75
+100
–100
0
10
Time (µs)
1µs
Time (µs)
15
10
25
®
OPA2604
–25
SMALL-SIGNAL TRANSIENT RESPONSE
–10
Slew Rate (V/µs)
20
–50
Ambient Temperature (°C)
LARGE-SIGNAL TRANSIENT RESPONSE
25
100k
SUPPLY CURRENT vs TEMPERATURE
30
30
10k
Frequency (Hz)
6
2µs
100
125
TYPICAL PERFORMANCE CURVES
(CONT)
At TA = +25°C, VS = ±15V, unless otherwise noted.
POWER DISSIPATION vs SUPPLY VOLTAGE
SHORT-CIRCUIT CURRENT vs TEMPERATURE
1
Worst case sine
wave RL = 600Ω
(both channels)
0.9
Power Dissipation (W)
ISC+ and ISC–
50
40
30
0.8
Typical high-level
music RL = 600Ω
(both channels)
0.7
0.6
0.5
0.4
No signal
or no load
0.3
0.2
20
0.1
–75
–50
–25
0
25
50
75
100
125
6
8
10
Ambient Temperature (°C)
12
14
16
18
20
22
24
Supply Voltage, ±VS (V)
MAXIMUM POWER DISSIPATION vs TEMPERATURE
1.4
Total Power Dissipation (W)
Short-Circuit Current (mA)
60
θJ-A = 90°C/W
Soldered to
Circuit Board
(see text)
1.2
1.0
0.8
0.6
Maximum
Specified Operating
Temperature
85°C
0.4
0.2
0
0
25
50
75
100
125
150
Ambient Temperature (°C)
®
7
OPA2604
APPLICATIONS INFORMATION
The OPA2604 is unity-gain stable, making it easy to use in a
wide range of circuitry. Applications with noisy or high
impedance power supply lines may require decoupling capacitors close to the device pins. In most cases 1µF tantalum
capacitors are adequate.
and capacitive load will decrease the phase margin and may
lead to gain peaking or oscillations. Load capacitance reacts
with the op amp’s open-loop output resistance to form an
additional pole in the feedback loop. Figure 2 shows various
circuits which preserve phase margin with capacitive load.
Request Application Bulletin AB-028 for details of analysis
techniques and applications circuits.
DISTORTION MEASUREMENTS
The distortion produced by the OPA2604 is below the measurement limit of virtually all commercially available equipment. A special test circuit, however, can be used to extend the
measurement capabilities.
For the unity-gain buffer, Figure 2a, stability is preserved by
adding a phase-lead network, RC and CC. Voltage drop across
RC will reduce output voltage swing with heavy loads. An
alternate circuit, Figure 2b, does not limit the output with low
load impedance. It provides a small amount of positive feedback to reduce the net feedback factor. Input impedance of this
circuit falls at high frequency as op amp gain rolloff reduces
the bootstrap action on the compensation network.
Op amp distortion can be considered an internal error source
which can be referred to the input. Figure 1 shows a circuit
which causes the op amp distortion to be 101 times greater
than normally produced by the op amp. The addition of R3 to
the otherwise standard non-inverting amplifier configuration
alters the feedback factor or noise gain of the circuit. The
closed-loop gain is unchanged, but the feedback available for
error correction is reduced by a factor of 101. This extends the
measurement limit, including the effects of the signal-source
purity, by a factor of 101. Note that the input signal and load
applied to the op amp are the same as with conventional
feedback without R3.
Figures 2c and 2d show compensation techniques for
noninverting amplifiers. Like the follower circuits, the circuit
in Figure 2d eliminates voltage drop due to load current, but
at the penalty of somewhat reduced input impedance at high
frequency.
Figures 2e and 2f show input lead compensation networks for
inverting and difference amplifier configurations.
NOISE PERFORMANCE
Op amp noise is described by two parameters—noise voltage
and noise current. The voltage noise determines the noise
performance with low source impedance. Low noise bipolarinput op amps such as the OPA27 and OPA37 provide very
low voltage noise. But if source impedance is greater than a
few thousand ohms, the current noise of bipolar-input op amps
react with the source impedance and will dominate. At a few
thousand ohms source impedance and above, the OPA2604
will generally provide lower noise.
Validity of this technique can be verified by duplicating
measurements at high gain and/or high frequency where the
distortion is within the measurement capability of the test
equipment. Measurements for this data sheet were made with
the Audio Precision System One which greatly simplifies
such repetitive measurements. The measurement technique
can, however, be performed with manual distortion measurement instruments.
CAPACITIVE LOADS
The dynamic characteristics of the OPA2604 have been
optimized for commonly encountered gains, loads and operating conditions. The combination of low closed-loop gain
R1
R2
SIG. DIST.
GAIN GAIN
1
R3
2
VO = 10Vp-p
(3.5Vrms)
OPA2604
Generator
Output
R2
R3
∞
5kΩ
50Ω
10
101
500Ω
5kΩ
500Ω
100
101
50Ω
5kΩ
∞
Analyzer
Input
Audio Precision
System One
Analyzer*
RL
1kΩ
* Measurement BW = 80kHz
FIGURE 1. Distortion Test Circuit.
®
OPA2604
R1
101
1
8
IBM PC
or
Compatible
(a)
(b)
CC
820pF
1
1
2
eo
eo
OPA2604
ei
750Ω
CL
5000pF
CC
0.47µF
CL
5000pF
CC =
2
OPA2604
RC
R2
RC
2kΩ
10Ω
ei
120 X 10–12 CL
RC =
CC =
R2
4CL X 1010 – 1
CL X 103
RC
(c)
(d)
R1
R2
R1
R2
10kΩ
10kΩ
CC
2kΩ
2kΩ
RC
20Ω
24pF
1
CC
0.22µF
RC
2
eo
OPA2604
ei
2
eo
ei
25Ω
CL
5000pF
50
CL
R2
CC =
1
OPA2604
RC =
CC =
CL
5000pF
R2
2CL X 1010 – (1 + R2/R1)
C L X 103
RC
(e)
(f)
R2
R1
R2
2kΩ
2kΩ
e1
2kΩ
R1
ei
1
2kΩ
RC
20Ω
2
1
eo
OPA2604
CC
0.22µF
RC
20Ω
CL
5000pF
CC
0.22µF
2
eo
OPA2604
R3
R4
2kΩ
2kΩ
CL
5000pF
e2
RC =
R2
2CL X 1010 – (1 + R2/R1)
RC =
CC =
CL X 103
RC
CC =
R2
2C L X 1010 – (1 + R2/R1)
C L X 103
RC
NOTE: Design equations and component values are approximate. User adjustment is required for optimum performance.
FIGURE 2. Driving Large Capacitive Loads.
®
9
OPA2604
Copper leadframe construction used in the OPA2604 improves heat dissipation compared to conventional plastic
packages. To achieve best heat dissipation, solder the device
directly to the circuit board and use wide circuit board traces.
POWER DISSIPATION
The OPA2604 is capable of driving 600Ω loads with power
supply voltages up to ±24V. Internal power dissipation is
increased when operating at high power supply voltage. The
typical performance curve, Power Dissipation vs Power Supply Voltage, shows quiescent dissipation (no signal or no
load) as well as dissipation with a worst case continuous sine
wave. Continuous high-level music signals typically produce
dissipation significantly less than worst case sine waves.
OUTPUT CURRENT LIMIT
Output current is limited by internal circuitry to approximately ±40mA at 25°C. The limit current decreases with
increasing temperature as shown in the typical curves.
R4
22kΩ
C3
R1
R2
100pF
R3
VIN
1
2.7kΩ
22kΩ
C1
3000pF
10kΩ
2
VO
OPA2604
C2
2000pF
fp = 20kHz
FIGURE 3. Three-Pole Low-Pass Filter.
1
R1
R5
2
OPA2604
VIN
6.04kΩ
2kΩ
R2
4.02kΩ
C3
1000pF
R2
4.02kΩ
1
Low-pass
3-pole Butterworth
f–3dB = 40kHz
2
OPA2604
1
2
OPA2604
C1
1000pF
R4
5.36kΩ
See Application Bulletin AB-026
for information on GIC filters.
C2
1000pF
FIGURE 4. Three-Pole Generalized Immittance Converter (GIC) Low-Pass Filter.
®
OPA2604
10
VO
C1*
I-Out DAC
R1
C2
2200pF
2kΩ
1
R2
R3
2.94kΩ
21kΩ
2
1
2
VO
OPA2604
OPA2604
COUT
C3
470pF
~
* C1 =
COUT
Low-pass
2-pole Butterworth
f–3dB = 20kHz
2π R1 fc
R1 = Feedback resistance = 2kΩ
fc = Crossover frequency = 8MHz
FIGURE 5. DAC I/V Amplifier and Low-Pass Filter.
1
7.87kΩ
10kΩ
2
10kΩ
OPA2604
–
1
VIN
100pF
2
OPA2604
VO
G=1
+
1
7.87kΩ
100kHz Input Filter
2
OPA2604
10kΩ
10kΩ
FIGURE 6. Differential Amplifier with Low-Pass Filter.
®
11
OPA2604
100Ω
1
COUT
* C1 ≈
10kΩ
Rf = Internal feedback resistance = 1.5kΩ
fc = Crossover frequency = 8MHz
G = 101
(40dB)
2
2π Rf fc
10
OPA2604
5
PCM63
20-bit
6
D/A
9
Converter
Piezoelectric
Transducer
1MΩ*
C1*
1
2
OPA2604
* Provides input bias
current return path.
FIGURE 7. High Impedance Amplifier.
FIGURE 8. Digital Audio DAC I-V Amplifier.
1/2 OPA2604
A2
I2
R4
1/2 OPA2604
R3
51Ω
51Ω
A1
VIN
IL = I1 + I2
i1
R2
VOUT
Load
R1
VOUT = VIN (1 + R2/R1)
FIGURE 9. Using the Dual OPA2604 Op Amp to Double the Output Current to a Load.
®
OPA2604
VO = ±3Vp
To low-pass
filter.
12