DATA SHEET
KH600
-10
5V
pp
@ 50MHz
800
600
-20
-30
Distortion (dB)
Output (mV)
-40
-50
-60
-70
-80
-90
3rd
400
200
OUT1, OUT2
0
2nd
-200
-400
-600
-100
40
60
80
100
120
140
-8
-6
-4
-2
0
Total Supply Current (mA)
-V
b
(V)
Figure 14: Harmonic Distortion vs. Total I
s
Figure 17: Output vs. -V
b
Trimming Differential Output Offset Voltage
Vary +V
b1
and +V
b2
to adjust differential offset voltage.
+V
b1
controls OUT1 and +V
b2
controls OUT2. The output
voltage moves in a direction opposite to the direction of the
bias voltage. Figure 15 shows the resulting voltage change at
OUT1 and OUT2 when the voltage on +V
b1
is changed.
Figure 16 shows the resulting voltage change at OUT1 and
OUT2 when the voltage on +V
b2
is changed. OUT1 and
OUT2 change at the same rate when -Vb is changed, as
shown in Figure 17. Therefore, changing the voltage on -V
b
has no effect on differential output offset voltage.
800
600
400
Adjusting Common Mode Output
Offset Voltage
Short +V
b1
to +V
b2
and vary +V
b
and -V
b
to adjust common
mode output offset voltage. The recommended values for
achieving a given output offset are shown in Figure 18. These
values were chosen to give the best distortion performance.
The exact values are not crucial.
6
4
2
0
+V
b1
, +V
b2
+V
s
= +7.5V
-V
s
= -3.5V
Volts (V)
OUT1
-2
-4
-6
-8
-V
b
Output (mV)
200
0
-10
OUT2
-12
0
1
2
3
4
-200
-400
-600
0
2
4
6
8
Common Mode Voltage (V)
Figure 18: V
b
vs. Common Mode Voltage
+V
b1
(V)
For common mode voltages of 0 to -3.5V swap the V
b
’s and
change the polarity. See the example below.
Desired Common
Mode Voltage
2 Volts
-2 Volts
Figure 15: Output vs. +V
b1
800
600
400
+V
b1
and +V
b2
(V)
2
8
-V
b
(V)
-8
-2
Output (mV)
200
0
OUT2
OUT1
-200
-400
-600
0
2
4
6
8
Figures 19 and 20 illustrate how the common mode voltage
effects harmonic distortion. Figure 21 shows the resulting I
s
and -I
s
supply currents.
Pay close attention to your peak-to-peak output voltage
requirement. As you change the common mode voltage, you
may need to increase or shift ±V
s
in order to achieve your
output requirements. A 2V margin is recommended. For
example, if your output requirement is 5V
pp
and you will be
REV. 2 January 2004
+V
b2
(V)
Figure 16: Output vs. +V
b2
10
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
