Frequency response analysis for switching converters in SPICE without averaging

Stability is the key requirement in designing switching converter ASIC. Achieving this requires an accurate loop gain design. Since DC-DC switching converters are time-varying system, traditional small signal analysis in SPICE cannot be directly used to simulate the loop gain of this kind of system. A new method named periodic small signal analysis is proposed to analyze and simulate DC-DC switching converter inside a SPICE like simulator without the need for averaging. This general method is suitable for any switching regulators. The results are accurate comparing with average modeling and experiment results even beyond half switching frequency. A general procedure to design loop gain is demonstrated in a peak current control buck.