KH103
DATA SHEET
with a 70kHz square wave large enough to produce a
transition from +5V to -5V at the KH103 output and
adjusting R
b
until the output of U1 is at a minimum. R
a
should be about 9.5R
g
for bad results; thus, R
b
should be
adjusted around the value of 0.5R
g
.
Distortion and Noise
The graphs of intercept point versus frequency on the
page 3 make it easy to predict the distortion at any fre-
quency, given the output voltage of the KH103. First con-
vert the output voltage V
o
to V
rms
= (V
pp
/2√2) and then to
P = (10log
10
(20V
rms2
)) to get the output power in dBm.
At the frequency of interest, its 2nd harmonic will be S
2
=
(I
2
- P) dB below the level of P. Its third harmonic will be
S
3
= 2(I
3
- P) dB below the level of P, as will the two-tone
third order intermodulation products. These approxima-
tions are useful for P < -1dB compression levels.
Approximate noise figure can determined for the KH103
using the Equivalent Input Noise graph on page 3. The
following equation can be used to determine noise figure
(F) in dB.
Figure 3: Non-Inverting Gain Composite Amplifier
to be Used with Figure 1 Circuit
Figure 4: Inverting Gain Composite Amplifier to be
Used with Figure 2 Circuit
Bias Control
In normal operation, the bias control pin (pin 16) is left
unconnected. However, if control over the bias of the
amplifier is desired, the bias control pin may be driven
with a TTL signal; a TTL high level will turn the amplifier
off.
where v
n
is the rms noise voltage and i
n
is the rms noise
current. Beyond the breakpoint of the curves (i.e. where
they are flat) broadband noise figure equals spot noise,
so
∆f
should equal one (1) and v
n
and i
n
should be read
directly off the graph. Below the breakpoint, the noise
must be integrated and
∆f
set to the appropriate band-
width.
REV. 1A January 2004
5
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
