Op-Amp Theory — Feedback, Noise & Active Filters

Engineering

Advanced 120 minutes 2 lessons

PhD-level operational amplifier analysis: ideal and non-ideal op-amp models, negative feedback stability (gain-bandwidth product, phase margin), input-referred noise analysis, and systematic active filter design using the Butterworth and Chebyshev approximations in Sallen–Key and multiple-feedback topologies.

Learning Objectives

Apply the virtual-short and virtual-open principles to analyse inverting, non-inverting, difference, and instrumentation amplifier configurations
Derive the closed-loop gain, bandwidth, and phase margin from the open-loop Bode plot and gain-bandwidth product
Compute input-referred voltage noise density and total integrated noise over a specified bandwidth
Design 2nd-order Butterworth and Chebyshev low-pass/high-pass filters using the Sallen–Key topology
Specify unity-gain bandwidth and slew rate to meet signal integrity requirements at a given frequency and amplitude