1
OPA27, 37
FEATURES
q
LOW NOISE: 4.5nV/
Hz max at 1kHz
q
LOW OFFSET: 100
V max
q
LOW DRIFT: 0.4
V/
C
q
HIGH OPEN-LOOP GAIN: 117dB min
q
HIGH COMMON-MODE REJECTION:
100dB min
q
HIGH POWER SUPPLY REJECTION:
94dB min
q
FITS OP-07, OP-05, AD510, AD517
SOCKETS
Ultra-Low Noise Precision
OPERATIONAL AMPLIFIERS
APPLICATIONS
q
PRECISION INSTRUMENTATION
q
DATA ACQUISITION
q
TEST EQUIPMENT
q
PROFESSIONAL AUDIO EQUIPMENT
q
TRANSDUCER AMPLIFIER
q
RADIATION HARD EQUIPMENT
DESCRIPTION
The OPA27/37 is an ultra-low noise, high precision
monolithic operational amplifier.
Laser-trimmed thin-film resistors provide excellent
long-term voltage offset stability and allow superior
voltage offset compared to common zener-zap tech-
niques.
A unique bias current cancellation circuit allows bias
and offset current specifications to be met over the full
55
C to +125
C temperature range.
The OPA27 is internally compensated for unity-gain
stability. The decompensated OPA37 requires a closed-
loop gain
5.
The Burr-Brown OPA27/37 is an improved replace-
ment for the industry-standard OP-27/OP-37.
OPA27
OPA37
Output
+V
CC
V
CC
+In
In
Trim
Trim
8
7
6
4
1
2
3
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
OPA27
OPA27
1984 Burr-Brown Corporation
PDS-466M
Printed in U.S.A. March, 1998
2
OPA27, 37
SPECIFICATIONS
At V
CC
=
15V and T
A
= +25
C, unless otherwise noted.
OPA27/37G
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
INPUT NOISE
(6)
Voltage, f
O
= 10Hz
3.8
8.0
nV/
Hz
f
O
= 30Hz
3.3
5.6
nV/
Hz
f
O
= 1kHz
3.2
4.5
nV/
Hz
f
B
= 0.1Hz to 10Hz
0.09
0.25
Vp-p
Current,
(1)
f
O
= 10Hz
1.7
pA/
Hz
f
O
= 30Hz
1.0
pA/
Hz
f
O
= 1kHz
0.4
0.6
pA/
Hz
OFFSET VOLTAGE
(2)
Input Offset Voltage
25
100
V
Average Drift
(3)
T
A MIN
to T
A MAX
0.4
1.8
(6)
V/
C
Long Term Stability
(4)
0.4
2.0
V/mo
Supply Rejection
V
CC
= 4 to 18V
94
120
dB
V
CC
= 4 to 18V
1
20
V/V
BIAS CURRENT
Input Bias Current
15
80
nA
OFFSET CURRENT
Input Offset Current
10
75
nA
IMPEDANCE
Common-Mode
2 || 2.5
G
|| pF
VOLTAGE RANGE
Common-Mode Input Range
11
12.3
V
Common-Mode Rejection
V
IN
=
11VDC
100
122
dB
OPEN-LOOP VOLTAGE GAIN, DC
R
L
2k
117
124
dB
R
L
1k
124
dB
FREQUENCY RESPONSE
Gain-Bandwidth Product
(5)
OPA27
5
(6)
8
MHz
OPA37
45
(6)
63
MHz
Slew Rate
(5)
V
O
=
10V,
R
L
= 2k
OPA27, G = +1
1.7
(6)
1.9
V/
s
OPA37, G = +5
11
(6)
11.9
V/
s
Settling Time, 0.01%
OPA27, G = +1
25
s
OPA37, G = +5
25
s
RATED OUTPUT
Voltage Output
R
L
2k
12
13.8
V
R
L
600
10
12.8
V
Output Resistance
DC, Open Loop
70
Short Circuit Current
R
L
= 0
25
60
(6)
mA
POWER SUPPLY
Rated Voltage
15
VDC
Voltage Range,
Derated Performance
4
22
VDC
Current, Quiescent
I
O
= 0mADC
3.3
5.7
mA
TEMPERATURE RANGE
Specification
40
+85
C
Operating
40
+85
C
NOTES: (1) Measured with industry-standard noise test circuit (Figures 1 and 2). Due to errors introduced by this method, these current noise specifications should
be used for comparison purposes only. (2) Offset voltage specification are measured with automatic test equipment after approximately 0.5 seconds from power turn-
on. (3) Unnulled or nulled with 8k
to 20k
potentiometer. (4) Long-term voltage offset vs time trend line does not include warm-up drift. (5) Typical specification only
on plastic package units. Slew rate varies on all units due to differing test methods. Minimum specification applies to open-loop test. (6) This parameter guaranteed by
design.
3
OPA27, 37
OPA27/37G
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
INPUT VOLTAGE
(1)
Input Offset Voltage
48
220
(3)
V
Average Drift
(2)
T
A MIN
to T
A MAX
0.4
1.8
(3)
V/
C
Supply Rejection
V
CC
= 4.5 to 18V
V
CC
= 4.5 to 18V
90
(3)
122
dB
BIAS CURRENT
Input Bias Current
21
150
(3)
nA
OFFSET CURRENT
Input Offset Current
E, F, G
20
135
(3)
nA
VOLTAGE RANGE
Common-Mode Input Range
10.5
(3)
11.8
V
Common-Mode Rejection
V
IN
=
11VDC
96
(3)
122
dB
OPEN-LOOP GAIN, DC
Open-Loop Voltage Gain
R
L
2k
113
(3)
120
dB
RATED OUTPUT
Voltage Output
R
L
= 2k
11.0
(3)
13.4
V
Short Circuit Current
V
O
= 0VDC
25
mA
TEMPERATURE RANGE
Specification
40
+85
C
NOTES: (1) Offset voltage specification are measured with automatic test equipment after approximately 0.5s from power turn-on. (2) Unnulled or nulled with 8k
to
20k
potentiometer. (3) This parameter guaranteed by design.
SPECIFICATIONS
At V
CC
=
15V and T
A
= +25
C, unless otherwise noted.
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.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ...................................................................................
22V
Internal Power Dissipation
(1)
........................................................ 500mW
Input Voltage ......................................................................................
V
CC
Output Short-Circuit Duration
(2)
................................................. Indefinite
Differential Input Voltage
(3)
.............................................................
0.7V
Differential Input Current
(3)
...........................................................
25mA
Storage Temperature Range .......................................... 55
C to +125
C
Operating Temperature Range ......................................... 40
C to +85
C
Lead Temperature:
P (soldering, 10s) ....................................................................... +300
C
U (soldering, 3s) ......................................................................... +260
C
PACKAGE TYPE
JA
UNITS
8-Pin Plastic DIP (P)
100
C/W
8-Pin SOIC (U)
160
C/W
NOTES: (1) Maximum package power dissipation vs ambient temperature. (2) To
common with
V
CC
= 15V. (3) The inputs are protected by back-to-back diodes.
Current limiting resistors are not used in order to achieve low noise. If differential
input voltage exceeds
0.7V, the input current should be limited to 25mA.
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.
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.
4
OPA27, 37
Top View
P, U Packages
CONNECTION DIAGRAMS
1
2
3
4
5
6
7
8
Offset Trim
+V
CC
In
+In
V
CC
Output
NC
Offset Trim
OFFSET
PACKAGE
TEMPERATURE
VOLTAGE
DRAWING
PRODUCT
(1)
PACKAGE
RANGE (
C)
MAX (
V), 25
C
NUMBER
(3)
OPA27GP
Plastic
40 to +85
100
006
OPA27GU
(2)
SOIC
40 to +85
100
182
NOTE: (1) Packages for OPA37 are same as for OPA27. (2) OPA27GU may
be marked OPA27U. Likewise, OPA37GU may be marked OPA37U. (3) For
detailed drawing and dimension table, please see end of data sheet, or
Appendix C of Burr-Brown IC Data Book.
PACKAGE/ORDERING INFORMATION
FIGURE 1. 0.1Hz to 10Hz Noise Test Circuit.
DUT
OPA111
100k
2k
4.7F
Voltage Gain
Total = 50,000
10
NOTE: All capacitor values are for nonpolarized capacitors only.
0.1F
Scope
x1
R
IN
= 1M
100k
24.3k
4.3k
110k
0.1F
22F
2.2F
FIGURE 2. Low Frequency Noise.
0.1Hz TO 10Hz NOISE
1s/div
40nV/div
5
OPA27, 37
TYPICAL PERFORMANCE CURVES
At T
A
= +25
C,
V
CC
=
15VDC, unless otherwise noted.
INPUT OFFSET VOLTAGE WARM-UP DRIFT
Time From Power Turn-On (min)
0
+10
+5
0
5
10
Offset Voltage Change (V)
1
2
3
4
5
6
G
TO-99
INPUT OFFSET VOLTAGE CHANGE
DUE TO THERMAL SHOCK
Time From Thermal Shock (min)
1
+20
+10
0
10
20
Offset Voltage Change (V)
0
+1
+2
+3
+4
+5
+25C
+70C
T = +25C to T = +70C
Fluid Bath
A
A
INPUT VOLTAGE NOISE vs NOISE BANDWIDTH
(0.1Hz to Indicated Frequency)
Noise Bandwidth (Hz)
100
1k
10k
100k
10
1
0.1
0.01
Voltage Noise (Vrms)
R = 0
S
TOTAL INPUT VOLTAGE NOISE SPECTRAL DENSITY
vs SOURCE RESISTANCE
Source Resistance ( )
100
1k
10k
100
80
60
10
8
6
40
20
4
2
1
Voltage Noise (nV/
Hz)
-
+
R
1
R
1
R = 2 R
1
x
SOURCE
Resistor Noise Only
1kHz
10Hz
VOLTAGE NOISE SPECTRAL DENSITY
vs SUPPLY VOLTAGE
5
4
3
2
1
0
Supply Voltage (V )
CC
5
10
15
20
Voltage Noise (nV/
Hz)
1kHz
10Hz
Voltage Noise (nV/
Hz)
VOLTAGE NOISE SPECTRAL DENSITY
vs TEMPERATURE
5
4
3
2
1
75
50
25
0
+25
+50
+75
+100
+125
Ambient Temperature (C)
10Hz
1kHz
6
OPA27, 37
TYPICAL PERFORMANCE CURVES
(CONT)
At T
A
= +25
C,
V
CC
=
15VDC, unless otherwise noted.
INPUT CURRENT NOISE SPECTRAL DENSITY
Current Noise (pA/
Hz)
10
8
6
4
2
1
0.8
0.6
0.4
0.2
0.1
10
100
1k
10k
This industry-standard equation
is inaccurate and these figures should
be used for comparison purposes only!
Current Noise Test Circuit
I
n =
(e
no
)
2
(130nV)
2
1M 100
x
DUT
100k
500k
500k
10k
e
no
Frequency (Hz)
Warning:
INPUT VOLTAGE NOISE SPECTRAL DENSITY
1
10
100
1k
Frequency (Hz)
Voltage Noise (nV/
Hz)
10
8
6
4
2
0
OPEN-LOOP FREQUENCY RESPONSE
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
100M
140
120
100
80
60
40
20
0
Voltage Gain (dB)
OPA27
OPA37
BIAS AND OFFSET CURRENT vs TEMPERATURE
Ambient Temperature (C)
75
50
25
0
+25
+50
+75
+100
+125
Absolute Bias Current (nA)
20
15
10
5
0
Absolute Offset Current (nA)
20
15
10
5
0
Bias
Offset
OPA27 CLOSED-LOOP VOLTAGE GAIN AND
PHASE SHIFT vs FREQUENCY (G = 100)
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
100M
Voltage Gain (dB)
Phase Shift (degrees)
50
40
30
20
10
0
10
20
0
45
90
135
180
225
Gain
OPA37 CLOSED-LOOP VOLTAGE GAIN AND
PHASE SHIFT vs FREQUENCY (G = 100)
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
100M
Voltage Gain (dB)
Phase Shift (degrees)
50
40
30
20
10
0
10
20
0
45
90
135
180
225
Gain
G = 5
7
OPA27, 37
TYPICAL PERFORMANCE CURVES
(CONT)
At T
A
= +25
C,
V
CC
=
15VDC, unless otherwise noted.
COMMON-MODE REJECTION vs FREQUENCY
140
120
100
80
60
40
20
0
Common-Mode Rejection (dB)
Frequency (Hz)
1
10
100
1k
10k
100k
1M
10M
OPA37
OPA27
OPEN-LOOP VOLTAGE GAIN vs SUPPLY VOLTAGE
130
125
120
115
Voltage Gain (dB)
5
Supply Voltage (V )
CC
10
15
20
25
R = 2k
L
R = 600
L
OPEN-LOOP VOLTAGE GAIN vs TEMPERATURE
Voltage Gain (dB)
135
130
125
120
115
Ambient Temperature (C)
75
50
25
0
+25
+50
+75
+100
+125
R
L
= 2k
SUPPLY CURRENT vs SUPPLY VOLTAGE
6
5
4
3
2
1
0
Supply Current (mA)
0
Supply Voltage (V )
CC
5
10
15
20
+25C
+125C
55C
COMMON-MODE INPUT VOLTAGE RANGE
vs SUPPLY VOLTAGE
+15
+10
+5
0
5
10
15
Common-Mode Range (V)
0
Supply Voltage (V )
CC
5
10
15
20
T = +25C
A
T = +125C
A
T = 55C
A
T = +25C
A
T = +125C
A
T = 55C
A
POWER SUPPLY REJECTION vs FREQUENCY
140
120
100
80
60
40
20
0
Power Supply Rejection (dB)
Frequency (Hz)
1
10
100
1k
10k
100k
1M
10M
OPA27
V
CC
+V
CC
8
OPA27, 37
TYPICAL PERFORMANCE CURVES
(CONT)
At T
A
= +25
C,
V
CC
=
15VDC, unless otherwise noted.
APPLICATIONS INFORMATION
OFFSET VOLTAGE ADJUSTMENT
The OPA27/37 offset voltage is laser-trimmed and will re-
quire no further trim for most applications. Offset voltage
drift will not be degraded when the input offset is nulled with
a 10k
trim potentiometer. Other potentiometer values from
1k
to 1M
can be used but V
OS
drift will be degraded by
an additional 0.1 to 0.2
V/
C. Nulling large system offsets
by use of the offset trim adjust will degrade drift performance
by approximately 3.3
V/
C per millivolt of offset. Large
system offsets can be nulled without drift degradation by
input summing.
The conventional offset voltage trim circuit is shown in
Figure 3. For trimming very small offsets, the higher resolu-
tion circuit shown in Figure 4 is recommended.
The OPA27/37 can replace 741-type operational amplifiers
by removing or modifying the trim circuit.
THERMOELECTRIC POTENTIALS
The OPA27/37 is laser-trimmed to microvolt-level input
offset voltage and for very low input offset voltage drift.
Careful layout and circuit design techniques are necessary to
prevent offset and drift errors from external thermoelectric
potentials. Dissimilar metal junctions can generate small
EMFs if care is not taken to eliminate either their sources
(lead-to-PC, wiring, etc.) or their temperature difference. See
Figure 11.
Short, direct mounting of the OPA27/37 with close spacing
of the input pins is highly recommended. Poor layout can
result in circuit drifts and offsets which are an order of
magnitude greater than the operational amplifier alone.
OPA27 SMALL SIGNAL TRANSIENT RESPONSE
Time (s)
+60
+40
+20
0
20
40
60
Output Voltage (mV)
0
1
2
A = +1
C = 15pF
VCL
L
0.5
1.5
2.5
OPA37 SMALL SIGNAL TRANSIENT RESPONSE
Time (s)
+60
+40
+20
0
20
40
60
Output Voltage (mV)
0.2
0.4
0.6
A = +5
C = 25pF
V
L
0
0.8
1.0
1.2
OPA27 LARGE SIGNAL TRANSIENT RESPONSE
Time (s)
+6
+4
+2
0
2
4
6
Output Voltage (V)
2
4
6
0
8
10
12
A = +1
VCL
OPA37 LARGE SIGNAL TRANSIENT RESPONSE
Time (s)
+15
+10
+5
0
5
10
15
Output Voltage (V)
1
2
3
0
4
5
6
A = +5
V
9
OPA27, 37
COMPENSATION
Although internally compensated for unity-gain stability, the
OPA27 may require a small capacitor in parallel with a
feedback resistor (R
F
) which is greater than 2k
. This
capacitor will compensate the pole generated by R
F
and C
IN
and eliminate peaking or oscillation.
INPUT PROTECTION
Back-to-back diodes are used for input protection on the
OPA27/37. Exceeding a few hundred millivolts differential
input signal will cause current to flow and without external
current limiting resistors the input will be destroyed.
Accidental static discharge as well as high current can
damage the amplifier's input circuit. Although the unit may
still be functional, important parameters such as input offset
voltage, drift, and noise may be permanently damaged as will
any precision operational amplifier subjected to this abuse.
Transient conditions can cause feedthrough due to the
amplifier's finite slew rate. When using the OP-27 as a unity-
gain buffer (follower) a feedback resistor of 1k
is recom-
mended (see Figure 6).
NOISE: BIPOLAR VERSUS FET
Low-noise circuit design requires careful analysis of all noise
sources. External noise sources can dominate in many cases,
so consider the effect of source resistance on overall opera-
tional amplifier noise performance. At low source imped-
ances, the lower voltage noise of a bipolar operational
amplifier is superior, but at higher impedances the high
current noise of a bipolar amplifier becomes a serious liabil-
ity. Above about 15k
the Burr-Brown OPA111 low-noise
FET operational amplifier is recommended for lower total
noise than the OPA27 (see Figure 5).
FIGURE 3. Offset Voltage Trim.
FIGURE 5. Voltage Noise Spectral Density Versus Source
Resistance.
FIGURE 6. Pulsed Operation.
FIGURE 8. Unity-Gain Inverting Amplifier.
OPA27
Output
Input
1k
1k
2
3
6
FIGURE 7. Low-Noise RIAA Preamplifier.
OPA37
Output
97.6k
G
40dB at 1kHz.
Metal film resistors.
Film capacitors.
R
L
and C
L
per cartridge
manufacturer's
recommendations.
100
2
3
6
0.03F
0.01F
7.87k
1F
20k
R
L
Moving
Magnet
Cartridge
C
L
1
2
3
4
6
4mV Typical Trim Range
NOTE: (1) 10k
to 1M
Trim Potentiometer
(10k
Recommended).
+V
CC
V
CC
OPA27/37
7
8
(1)
FIGURE 4. High Resolution Offset Voltage Trim.
1
2
3
4
6
280V Typical Trim Range
NOTE: (1) 1k
Trim Potentiometer.
+V
CC
V
CC
OPA27/37
7
8
4.7k
4.7k
(1)
OPA27
Output
1.9V/s
R
F
1k
Input
+
100
1k
10k
100k
1M
10M
1k
100
10
1
Voltage Noise Spectral Density, E
O
Typical at 1kHz (nV/
Hz)
OPA111 + Resistor
OPA27 + Resistor
Source Resistance, R
S
(
)
E
O
R
S
E
O
=
e
n
2
+ (i
n
R
S
)
2
+ 4kTR
S
F
O
= 1kHz
Resistor Noise Only
OPA27 + Resistor
OPA111 + Resistor
Resistor Noise Only
10
OPA27, 37
10k
0.5V
0.5V
0.5V
0.5V
5V
A. 741 noise with circuit well-shielded from air
currents and RFI. (Note scale change.)
B. OP-07AH with circuit well-shielded from air
currents and RFI.
C. OPA27AJ with circuit well-shielded from air
currents and RFI. (Represents ultimate
OPA27 performance potential.)
D. OPA27 with circuit unshielded and exposed
to normal lab bench-top air currents.
(External thermoelectric potentials far
exceed OPA27 noise.)
E. OPA27 with heat sink and shield which
protects input leads from air currents.
Conditions same as (D).
Offset
G =1k
10Hz Low-
Pass Filter
Chart
Recorder
10mV/mm
5mm/s
DUT
Total Gain = 10
6
10
FIGURE 11. Low Frequency Noise Comparison.
FIGURE 10. NAB Tape Head Preamplifier.
OPA37
Output
316k
4.99k
G
50dB at 1kHz.
Metal film resistors.
Film capacitors.
R
L
and C
L
per head
manufacturer's
recommendations.
100
2
3
6
0.01F
1F
20k
R
L
Magnetic Tape Head
C
L
FIGURE 9. High Slew Rate Unity-Gain Inverting Amplifier.
OPA37
Output
Input
1k
1k
2
3
6
500pF
250
11
OPA27, 37
OPA37
Output
1k
2k
EDO 6166
Transducer
Frequency Response
1kHz to 50kHz
2
3
6
1M
200
500pF
0.1F
FIGURE 12. Low Noise Instrumentation Amplifier.
FIGURE 13. Hydrophone Preamplifier.
FIGURE 14. Long-Wavelength Infrared Detector Amplifier.
Output
NOTE: Use metal film resistors
and plastic film capacitor. Circuit
must be well shielded to achieve
low noise.
Responsivity
2.5 x 10
4
V/W
Output Noise
30Vrms, 0.1Hz to 10Hz
Dexter 1M
Thermopile
Detector
100
100k
OPA27
2
3
6
0.1F
FIGURE 15. High Performance Synchronous Demodulator.
Output
4.99k
D2
D1
DG188
TTL
In
S1
S2
9.76k
500
Balance
Trim
OPA27
2
3
1
8
6
20pF
10k
1k
4.75k
Offset
Trim
4.75k
+V
CC
Input
TTL INPUT
"1"
"0"
GAIN
+1
1
Output
OPA37
2
3
6
OPA37
3
2
6
6
1
5
3
2
Burr-Brown INA105
Differential Amplifier
Input Stage Gain = 1 + 2R
F
/R
G
+In
In
R
G
101
R
F
5k
R
F
5k
Gain = 100
Bandwidth
500kHz
For gain = 1000 use INA106 differential amplifier.
25k
25k
25k
25k
12
OPA27, 37
2k
Gain = 1010V/V
Full Power Bandwidth
180kHz
Gain Bandwidth
500MHz
Equivalent Noise Resistance
50
Signal-to-Noise Ratio
N
since amplifier noise is
uncorrelated.
2k
6
2
3
20
6
2
3
6
2
3
2k
6
2
3
6
2
3
OPA37
OPA37
OPA37
OPA37
OPA37
6
Output
2
3
OPA37
N = 10 Each OPA37EZ
2k
2k
2k
2k
2k
20
2k
20
2k
20
2k
20
Input
FIGURE 16. Ultra-Low Noise "N" Stage Parallel Amplifier.
13
OPA27, 37
OPA37
Output
Input
1k
2
3
6
500pF
250
5V
5s
R
S
= 50
+10V
0V
Output
10V
FIGURE 18. High Slew Rate Unity-Gain Buffer.
FIGURE 17. Unity-Gain Buffer.
OPA27
Output
Input
1k
2
3
6
5V
5s
R
S
= 50
+10V
0V
Output
10V
FIGURE 20. Balanced Pyroelectric Infrared Detector.
OPA27
Output
10k
100
100F/20V
Tantalum
2
3
6
+
+
1
3
2
10k
10k
10F/20V
Siemens LHI 948
+15V
FIGURE 19. RF Detector and Video Amplifier.
OPA37
Video
Output
20k
200
VIRTEC V1000
Planar Tunnel
Diode
2
3
6
0.01F
50
Input
200
RFC
500pF
FIGURE 21. Magnetic Tachometer.
OPA27
Output
0
+
4.8V
1k
2
3
Airpax
Magnetic
Pickup
f
OUT
RPM X N
Where N = Number of Gear Teeth
6
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