Circuit Theory-2 #25 | Active Band-Pass, Band-Reject and Butterworth Filters

Instructor: Dr. Süleyman Burak ÇELİK

In this Circuit Theory-2 lesson we extend active filters from low-pass and high-pass forms into middle-band behavior: active band-pass, active band-reject, and the Butterworth idea. You will learn: - How low-pass and high-pass edges create a useful middle band - Why an active band-pass filter can be built as a high-pass stage followed by buffer or gain and then a low-pass stage - How center frequency, lower edge, upper edge, bandwidth, and quality factor relate - Why active band-reject filters combine a direct path with a frequency-selective path - How notch depth depends on matching - What Butterworth means: a maximally flat pass band - How filter order changes roll-off slope - A practical workflow for choosing filter type, order, cutoff values, gain, and real op-amp constraints Timestamps: 00:00 Active band-pass, band-reject and Butterworth filters 00:03 From first-order edges to middle-band filters 00:24 The middle-band goal 00:48 Active band-pass by cascade 01:10 Band-pass gain and cutoff equations 01:37 Active band-reject path 01:59 Band-reject parameters 02:22 Butterworth idea 02:44 Filter order and slope 03:05 Design workflow 03:28 Practical limits 03:51 Summary Next lesson: more active-filter design practice and implementation details. Part of the Circuit Theory-2 playlist by AcEdumy.