A Feed-Forward Power-Supply Noise Cancellation Technique for Single-Ended Class-D Audio Amplifiers Adrian I. Colli-Menchi , Student Member , IEEE , Joselyn Torres , Student Member , IEEE ,a n d

Abstract

This paper presents a feed-forward power-supply noise cancellation technique to achieve hig h power-supply rejec- tion ratio (PSRR) in single-ended class-D audio ampli fiers. To show the effectiveness of the technique, it is implemented on a first-order single-e nded pulse-width mod ulation (PWM) class-D amplifier. The implemented technique improves the PSRR from 20 Hz to 20 kHz independently of the close-loop compensator’s filter-order. The design methodolog y, implementation, and trade- offs for the proposed technique are provided. The fabricated class-D audio ampli fier achieves a PSRR of 83 dB at 217 Hz, THD+N of 0.0149%, and a maximum ef ficiency of 94.6% from a 1.8-V power supply. Experimental results show a PSRR im- provement of 33 dB from 20 Hz to 20 kHz compared to a similar amplifier designed without the t echnique. The prototype was implemented using 0.18- m CMOS standard technology, and occupies a total area of 0.121 mm . The total quiescent power consumption was 356 W. The feed-forward power-supply noise cancellation technique enhances single-ended structures to achieve a PSRR performance comparable to differential architecture, and a tt h es a m et i m ei tc o n s u mes small quiescent power with a reduced active silicon area overhead.