KH600
pply Current vs.
±
DATA SHEET
Single-to-Differential Operation
The KH600 is specifically designed for differential-to-
differential operation. However, the KH600 can be used in a
single-to-differential configuration with some performance
degradation. The unused input should be terminated into 50Ω.
When driven single-ended, there will be a slight imbalance in
the differential output voltages, see Figure 5. This imbalance
is approximately 2.88dB. To compensate for this imbalance,
attenuate the higher gain output. (If the signal is applied to
IN1, attenuate OUT1.)
Total supply Current (mA)
100
90
80
70
60
50
40
30
20
10
0
0
2
4
6
8
±V
b
=
±5V
Unused Inputs and/or Outputs
For optimal performance, terminate any unused inputs and/or
outputs with 50Ω.
Supply Voltage (±V)
Figure 11: Total Supply Current vs. V
s
1100
The KH600 operates class A, so maximum output current is
directly proportional to supply current. Adjusting the voltages
on +V
b1
and +V
b2
in opposition to -V
b
controls supply
current. The default supply current of the KH600 has been
optimized for best bandwidth and distortion performance. The
main reason for adjusting supply current is to either reduce
power or increase maximum output current. Adjusting the
supply current will not significantly improve bandwidth or
distortion and may actually degrade them.
To adjust the supply current, apply voltages of equal magnitude,
but opposite polarity, to the bias voltage pins. For example,
setting +V
b1
, +V
b2
to +5VDC and -V
b
to -5VDC (as shown
in Figure 3) results in the standard supply current condition.
Setting +V
b1
, +V
b2
to +5.5V and -V
b
to -5.5V results in an
approximate 10% increase in supply current. Figure 10 shows
the how the total supply current of the KH600 is effected by
changes in the bias voltages (V
b
= +V
b1
= +V
b2
= |-V
b
|).
160
±V
s
=
±5V
-3dB Bandwidth (MHz)
Adjusting Supply Current
1000
900
800
700
600
500
40
60
80
100
120
140
Total Supply Current (mA)
Figure 12: -3dB Bandwidth vs. I
s
-40
2V
pp
@ 50MHz
-50
Distortion (dB)
3rd
-60
-70
-80
2nd
Total supply Current (mA)
140
120
100
80
60
40
20
0
0
-90
-100
40
60
80
100
120
140
Total Supply Current (mA)
Figure 13: Harmonic Distortion vs. Total I
s
2
4
6
8
V
b
(V)
Figure 10: Total Supply Current vs. V
b
Supply current is relatively independent of the voltages on
+V
s
and -V
s
as shown in Figure 11.
REV. 2 January 2004
9
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
