Switching Power Supplies A - Z, 2nd Edition

Chapter 12

Feedback Loop Analysis and Stability

This chapter advances from the very basics to full stability analysis of power converters. Time and frequency domain analyses are first explained along with the s-plane and the underlying concept behind the Laplace transform. Mathematics in the log-plane is described, and passive filter responses are plotted out. The concept of poles and zeros follows. Basic control loop theory is explained, and the plant transfer functions of the fundamental topologies are all derived. Transconductance amplifiers (OTAs) are compared with conventional voltage op-amps, and it is shown how to use them for implementing a feedback section and thereby closing the loop. Types 1–3 compensation techniques are discussed ...