State Variable Filter: One Biquad Structure, Three Simultaneous OutputsTransfer Function The State Variable Filter (SVF) implements three simultaneous outputs — lowpass (LP), highpass (HP), and bandpass (BP) — from a single shared pole structure. All three biquads share May 1 · 5 min readpowerelecsw.hashnode.dev
FIR Lowpass Kaiser Window: Linear-Phase Precision for Control Signal FilteringEvery IIR lowpass filter we have covered — Butterworth, Chebyshev, Elliptic — achieves steep rolloff at the cost of nonlinear phase, meaning different frequency components are delayed by different amoApr 26 · 7 min readpowerelecsw.hashnode.dev
Butterworth Lowpass 4th Order: 80 dB/Decade Rolloff With Zero Passband RippleA 2nd-order Butterworth gives you 40 dB/decade. Double the order to fourth and you get 80 dB/decade — the same maximally flat passband, twice the stopband suppression. At fc = 1000 Hz with fs = 44100 Apr 26 · 6 min readpowerelecsw.hashnode.dev
High Shelf Biquad: Boost High Frequencies Without Distorting Your Control BandwidthEvery sensor signal chain has a frequency-dependent noise floor. Below the shelf frequency the signal is clean; above it, quantization noise, switching harmonics, or electromagnetic interference dominApr 26 · 7 min readpowerelecsw.hashnode.dev
Low Shelf Biquad: DC-Range Gain Shaping Without Integrator Wind-UpA pure integrator (pole at z = 1) delivers infinite DC gain and infinite wind-up risk. A low shelf biquad gives you the same low-frequency gain boost with a defined upper limit, no saturation algebra Apr 22 · 6 min readpowerelecsw.hashnode.dev
