Limit Cycle-Free Digitally Controlled DC-DC Converters based on Dyadic Digital PWM

Quantization-induced limit cycle oscillations (LCOs) in digitally controlled dc–dc converters are addressed in this article. The novel dyadic digital pulsewidth modulator is proposed to increase the effective pulsewidth modulator resolution, as required for LCO-free operation, at low cost, without sacrificing dc accuracy and with no detrimental effects on the ripple voltage. Experimental results on a synchronous buck validate the approach highlighting effective LCOs’ suppression and dc accuracy enhancement at 5× reduced peak output voltage ripple and up to 16-dB lower frequency harmonic component reduction compared to thermometric dithering for the same resolution increase.