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Features
I
165MHz closed-loop – -3dB bandwidth
I
15ns settling to 0.05%
I
1mV input offset voltage, 10
μ
V/
°
C drift
I
100mA output current
I
Excellent AC and DC linearity
I
Direct replacement for CLC231
Applications
I
Driving flash A/D converters
I
Precision line driving
(a gain of 2 cancels matched-line losses)
I
DAC current-to-voltage conversion
I
Low-power, high-speed applications (50mW @ ±5V)
General Description
The KH231 Buffer/Amplifier is a wideband operational
amplifier designed specifically for high-speed, low-
gain applications. The KH231 is based on a current
feedback op amp topology-a unique design that both
eliminates the gain-bandwidth tradeoff and permits
unprecedented high-speed performance. (See table below.)
The KH231 Buffer/Amplifier is the ideal design alter-
native to low precision open-loop buffers and oscillation-
prone conventional op amps. The KH231 offers precise
gains from ±1.000 to ±-5.000 and linearity that is a
true 0.1%-even for demanding 50
loads. Open-loop
buffers, on the other hand, offer a nominal gain of
0.95 ±0.03 and a linearity of only 3% for typical loads.
A buffer
’
s settling time may look impressive but it is
usually specified at unrealistically large load resis-
tances or when the effects of thermal tail are not
included; the KH231 Buffer/Amplifier settles to 0.05%
in 15ns-while driving a 100
load.
Offsets and drifts, usually a low priority in conven-
tional high-speed op amp designs, were not ignored
in the KH231; the input offset voltage is typically 1mV
and input offset voltage drift is only 10
μ
V/
°
C. The
KH231 is stable and oscillation-free across the entire
gain range and since it
’
s internally compensated, the
user is saved the trouble of designing external com-
pensation networks and having to
“
tweak
”
them in
production. The absence of a gain-bandwidth trade-
off in the KH231 allows performance to be predicted
easily; the table below shows how the bandwidth is
affected very little by changing the gain setting.
The KH231 is constructed using thin film resistor/bipolar
transistor technology, and is available in the following
versions:
The KH231 is constructed using thin film resistor/bipolar
transistor technology, and available in these versions:
KH231AI
KH231AK
-25
°
C to +85
°
C
-55
°
C to +125
°
C
12-pin TO-8 can
12-pin TO-8 can, features
burn-in & hermetic testing
12-pin TO-8 can,
environmentally
screened and electrically
tested to MIL-STD-883
SMD#: 5962-8959401HXC
SMD#: 5962-8959401HXA
KH231AM
-55
°
C to +125
°
C
KH231HXC
KH231HXA
-55
°
C to +125
°
C
-55
°
C to +125
°
C
KH231
Fast Settling, Wideband Buffer/Amplifier (Av= ±1 to ±5)
www.fairchildsemi.com
REV. 1A February 2001
Small Signal Pulse Response
O
Time (5ns/div)
A
v
= -2
A
v
= 2
Supply
8
Adjust
7
GND
9
-V
CC
2
Adjust
3
GND
1
+V
CC
6
V+
5
V-
4
NC
10
-V
CC
V
o
+V
CC
11
12
4
4
Collector
Output
Collector
Supply
I
CC
Adjust
I
CC
Adjust
gCase
Non-InvInput
InvInput
ConneNot
grCase
+
-
Bottom View
Pins 2 and 8 are used to adjust the supply current or to adjust the off-
set voltage (see text). These pins are normally left unconnected.
Typical Performance
Gain Setting
5
Parameter
1
2
-1
-2
-5
Units
-3dB bandwidth
rise time (2V)
slew rate
settling time (to 0.1%)
180 165 130 165 150 115
1.8
2.0
2.5
2.5
3.0
3.0
12
12
12
MHz
ns
V/ns
ns
2.0
3.0
12
2.2
3.0
12
2.9
3.0
15