It is seen that the response of the circuit may be altered in the vicinity of the
cutoff frequency by changing the value of damping
j3
•
The damping is a
function of the gain of the operational amplifier which , in tum, is determined
by the ratio of resistors Rl and R2 .
Likewise, the overall response of a cascade of such prototype sections may be
tailored by appropriate selection of damping and the desired higher-order filter
may thus be synthesized.
In the Model 452, a fourth order Flat-Amplitude , or Butterworth filter ( per channel)
is synthesized in this manner, wnile on eighth-order Butte rworth filter is synthesized
i n the Model 852 . The F lat-Delay response is obtained in either model by
appropriate changes in the damping of the prototype sections .
IN
R
R
T
Fig.
3- 3.
2nd Order Low-Pass Prototype
OUT
Rl
R2
3-5
Summary of Contents for 452
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