Design and implementation of a switching DC-DC converter IC using sigma-delta modulator

Abstract

This paper presents an integrated sigma-delta noise-suppression buck converter using a discrete-time second order single-bit sigma-delta modulator (DT-SDM2). The context includes the description of small signal analysis and circuit design flow. The DT-SDM2 buck converter was designed and fabricated with a standard TSMC 0.35μm 3.3V CMOS process. The operating frequency of the proposed DT-SDM2 ranges from 1 to 5MHz. Compared to traditional pulse width modulator (PWM), using DT-SDM2 to control has greater noise suppressing ability. The measurement results show that the DT-SDM2 controlled converter suppresses the switching tones by 60dB at the switching frequency of 1MHz, and suppresses the switching tones by 30dB at the switching frequency of 5MHz.