DATA SHEET
KH600
Typical Operating Characteristics
(G = +5V/V (14dB), R
L
= 100Ω (differential), T
a
= +25°C, +V
b1
= +V
b2
= +V
s
= +5V, -V
b
= -V
s
= -5V; unless noted)
Output Offset vs. Temperature
0
-10
4
3
2
Differential Output Offset vs. Temperature
Output (mV)
Output (mV)
Inputs/outputs terminated
into 50Ω to GND
-20
-30
-40
-50
1
0
-1
-2
--3
-4
-40
-20
0
20
40
60
80
OUT1
OUT2
-40
-20
0
20
40
60
80
Temperature (°C)
Low Frequency Gain vs. Temperature
14.2
8
6
14.1
4
Temperature (°C)
Clipping Response
Output (V)
Gain (dB)
2
0
-2
-4
-6
14
13.9
13.8
0
20
40
60
80
-8
Time (2ns/div)
Temperature (°C)
Functional Description
The circuit is a differential amplifier with current output and
feedback. The simplified schematic is shown in Figure 1. The
output impedance is set by the value of the feedback resistors
(R3-R6) and the gain of the current mirrors. Amplifier gain is
set by R1 and R2. All of these resistors are internal due to the
high bandwidth of the amplifier.
The common mode output voltage (both outputs together) can
be varied by changing the voltages on +V
b1
, +V
b2
and -V
b
.
Making all three voltages more negative (for instance, +V
b
’s
change from +5 to +3, and -V
b
changes from -5 to -7) will
cause the output common mode level to become more positive.
The opposite conditions will cause the output common mode
level to become more negative. This can be very useful in driving
differential circuits which have an elevated DC common
mode input level. See
Adjusting Common Mode Output
Offset Voltage
section for more details.
By varying +V
b1
and +V
b2
differentially, the differential out-
put offset can be adjusted. See
Trimming Differential Output
Offset Voltage
for more details.
+OUT
+V
s
+V
b1
+V
b2
+V
s
Current Mirror 3x
out
in
R9
400
R10
400
in
Current Mirror 3x
out
Q1
Q2
-OUT
R3
356
R1
56
R5
356
R4
356
+IN
R11
50
Q3
R7
400
R2
56
Q4
R8
400
R6
356
-IN
R12
50
in
out
Current Mirror 3x
in
out
Current Mirror 3x
-V
s
-V
b
-V
s
Figure 1: KH600 Simplified Schematic
6
REV. 2 January 2004
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
