ABSTRACT
In our previous chapters on linear and switching regulators, our discussions did not consider the detailed aspects of the feedback loop used in the topology. In a well-designed DC-DC converter, irrespective of the load behavior, under all load currents the power supply should be free of any stray oscillations, and the DC rails should not fluctuate beyond specified margins. In a real-world, practical power supply design, when we consider the nonideal components such as op-amps, smoothing capacitors (with finite ESR), and inductors and transformers with parasitics, the design of the control loop becomes a challenge. This is further complicated by the finite frequency response properties of BJTs and MOSFETS, which have junction capacitances and other complex secondary elements. The subject of stability of a power supply that pertains to the closed-loop frequency response of the DC-DC converter has received much attention during the past quarter century. This chapter provides a summary of essential theory and different practical approaches to get the best control loop design without a rigorous mathematical approach.
