Page 200 - Analog and Digital Filter Design

Bandpass Filters 19

Let C = 10puF.

Let R = 22 kO.

Substituting the values&’= 82.81, fR’ = 105.165,fz’ = 201.44 and Q2 = 441, gives
R6 = 22kOl5.2135792 = 4.21975kO.

Reference

1. Williams, A., and E J. Taylor. Electronic Filter Design Handbook, New
York. McGraw-Hill, 1988.

Exercises

6.1 Starting with a passive normalized lowpass filter design, what step-by-
step processes must be performed in order to produce a bandpass
design?
4.2 A passive lowpass Cauer type filter has a parallel LC network in each
series arm. A parallel LC circuit has high impedance at the resonant
frequency and, when in a filter circuit, this produces a notch in the fre-
quency response. This notch is mathematically equivalent to a “zero”
in the S-plane. A bandpass filter has two zeroes in the S-plane for each
lowpass zero. How is the parallel LC circuit of the lowpass filter trans-
lated into the bandpass design?

4.3 An active multiple feedback bandpass (MFBP) filter stage has a
Q = 10 and resonant frequency, fR = 80 kHz. Given that C = 220 pF
and the gain at resonance is 20, find the values of RI, K2, and R3.