Op Amps for Everyone, 5th Edition

16.5. Band-Pass Filter Design

In Section 16.4, a high-pass response was generated by replacing the term S in the low-pass transfer function with the transformation 1/S. Likewise, a band-pass characteristic is generated by replacing the S term with the transformation:

1ΔΩ(s+1s)

(16.7)

In this case, the passband characteristic of a low-pass filter is transformed into the upper passband half of a band-pass filter. The upper passband is then mirrored at the mid frequency, f_m (Ω = 1), into the lower passband half (See Fig. 16.31).

The corner frequency of the low-pass filter transforms to the lower and upper −3 dB frequencies of the band-pass, Ω₁ and Ω