Example 16–2. Second-Order Unity-Gain Tschebyscheff Low-Pass Filter
The task is to design a second-order unity-gain Tschebyscheff low-pass filter with a corner
frequency of fC = 3 kHz and a 3-dB passband ripple.
From Table 16–9 (the Tschebyscheff coefficients for 3-dB ripple), obtain the coefficients
a1 and b1 for a second-order filter with a1 = 1.0650 and b1 = 1.9305.
Specifying C1 as 22 nF yields in a C2 of:
C2 C1
4b1
a1
2 22·109nF ·
4 ·1.9305
1.0652
150 nF
Inserting a1 and b1 into the resistor equation for R1,2 results in:
R1
1.065·150·109 1.065·150·109
2
4·1.9305·22·109 ·150·109
4·3·103·22·109·150·109 1.26 k
and
R2
1.065·150·109 1.065·150·109
2
4·1.9305·22·109 ·150·109
4·3·103·22·109·150·109 1.30 k
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