A switched-capacitor DC-DC converter using delta-sigma digital pulse frequency modulation control method

This paper presents a switched capacitor (SC) DC-DC converter using digital control method based on delta-sigma pulse frequency modulation (PFM) to accomplish a fast transient recovery time when output load changes rapidly. The DC-DC converter utilizes the first-order error feedback delta-sigma algorithm to control the switching frequency of the digitally controlled oscillator (DCO) using thermometer code. The load voltage of the SC DC-DC converter is regulated by the switching frequency of the DCO output based on the error between the load voltage and the reference voltage. The digital control method has two operation modes for fast transient recovery time; course and fine tuning modes to change the DCO's switching frequencies fast and accurately. The proposed converter accomplishes 72% power conversion efficiency, settling time of less than 460ns, and maximum deliverable output power of 230mW. The estimated total power consumption of the control loop is less than 0.82mW at 1.6V operation voltage.