2d ago · 6 min read · A 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
Join discussion2d ago · 6 min read · Every filter you've used so far in this series attenuates some frequencies. The allpass filter does something different: it leaves the magnitude spectrum completely untouched — 0 dB gain at every freq
Join discussionApr 18 · 5 min read · Elliptic (Cauer) filters achieve the steepest possible transition from passband to stopband for a given filter order. They pay for this with equiripple in both passband and stopband — but when embedde
Join discussionApr 17 · 5 min read · Every PID loop has a dirty secret: the derivative term amplifies noise. A step change or a noisy measurement causes the D-term to spike — saturating the actuator, stressing the plant, and sometimes de
Join discussionApr 17 · 5 min read · Every control engineer eventually asks: why does my filtered signal ring, overshoot, or arrive late? Butterworth gives you a flat magnitude response, but its non-linear phase smears signals in time. T
Join discussionApr 17 · 6 min read · The moving average is the most-deployed FIR filter in embedded control systems — one accumulator, one subtraction, zero multiply overhead on a power-of-2 window. But "simplest" does not mean "unintell
Join discussionApr 18 · 6 min read · Butterworth and Chebyshev Type I both ripple in one region to save on order—Butterworth ripples in the transition band (gentle rolloff), Type I ripples in the passband. The Chebyshev Type II flips the
Join discussionApr 17 · 6 min read · A motor drive switching at 10 kHz induces 50 Hz ripple in your torque estimate. A resolver excitation tone bleeds into your current feedback. A 60 Hz mains hum corrupts an ADC reading. In each case yo
Join discussionApr 18 · 6 min read · Butterworth gives you a maximally flat passband but pays for it with a gentle rolloff slope. If your control loop or ADC post-processor needs a harder cutoff at the same filter order, the Chebyshev Ty
Join discussionApr 17 · 6 min read · The first-order IIR lowpass is the workhorse of embedded DSP. One multiply, one add, one state variable — yet it is the default pre-filter on PID derivative terms, the ADC post-smoother in motor drive
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