
Component parasitics also influence high frequency
results, therefore it is recommended to use metal film
resistors such as RN55D or leadless components such
as surface mount devices. High profile sockets are not
recommended. If socketing is necessary, it is recom-
mended to use low impedance flush mount connector
jacks such as Cambion (P/N 450-2598).
Application Circuits
Four-Quadrant Multiplier
Applications requiring multiplication, squaring or other
non-linear functions can be implemented with four-quad-
rant multipliers. The CLC522 implements a four-quad-
rant multiplier as illustrated in figure 8.
Frequency Shaping
Frequency shaping and bandwidth extension of the
CLC522 can be accomplished using parallel networks
connected across the R
g
ports. The network shown in the
Fig. 9 schematic will effectively extend the CLC522's
bandwidth.
2nd Order Tuneable Bandpass Filter
The CLC522 Variable-Gain Amplifier placed into feed-
back loops provide signal processing functions such as
2nd order tuneable bandpass filters. The center fre-
quency of the 2nd order bandpass illustrated on the front
page is adjusted through the use of the CLC522's gain-
control voltage, V
g
. The integrators implemented with
two CLC420s, provide the coefficients for the transfer
function.
V
√
H
Input Referred Voltage Noise vs A
Vmax
0
10
20
MaximumGain Setting, A
Vmax
(V/V)
30
40
50
60
70
80
90 100
100
10
1
Circuit Layout Considerations
Please refer to the CLC522 Evaluation Board Literature
for precise layout guidelines. Good high-frequency op-
eration requires all of the de-coupling capcitors shown in
Fig. 6 to be placed as close as possible to the power
supply pins in order to insure a proper high-frequency
low-impedance bypass. Adequate ground plane and low-
inductive power returns are also required of the layout.
Minimizing the parasitic capacitances at pins 3, 4, 5, 6, 9,
10 and 12 as shown in Fig. 7 will assure best high
frequency performance. Vref (pin 9) to ground should
include a small resistor value of 25 ohms or greater to
buffer the internal voltage follower. The parasitic induc-
tance of component leads or traces to pins 4, 5 and 9
should also be kept to a minimum. Parasitic or load
capacitance, C
L
, on the output (pin 10) degrades phase
margin and can lead to frequency response peaking or
circuit oscillation. This should be treated with a small
series resistor between output (pin 10) and C
L
(see the
plot “Settling Time vs. Capacitive Load" for a recom-
mended series resistance).
Fig. 5
Fig. 6
Fig. 7
R
f
R
g
R
T
50
50
50
V
baseband
V
out
V
carrier
25
10
12
3
4
2
9
5
6
CLC522
R
m
=
2R
g
1.85
R
1
= R
T
|| R
m
|| R
s
R
1
R
s
R
T
=
R
m
R
s
R
m
-R
s
Fig. 8
Fig. 9
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