An equal-component Sallen-Key low-pass section is built with gain for a target
PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Feedback, operational amplifiers and analogue signal processing · Feedback, operational amplifiers and analogue signal processing
Inside the Instrument, Ch Filters, crystal oscillators and phase-locked loops
Problem
An equal-component Sallen-Key low-pass section is built with gain K=3−1/Q for a target Q=5, where K is set by two feedback resistors.
((a)) Find the value of K needed.
((b)) Compute the sensitivity SKQ=KQ.
((c)) Use the first-order sensitivity to estimate the percentage change in Q for a 1% increase in K.
((d)) Compute the exact new value of Q for that 1% increase in K, and state the exact percentage change.