A Feed-Forward Power-Supply Noise Cancellation Technique for Single-Ended Class-D Audio Amplifiers

作者：Colli Menchi Adrian I^*; Torres Joselyn; Sanchez Sinencio Edgar

来源：IEEE Journal of Solid-State Circuits, 2014, 49(3): 718-728.

DOI：10.1109/JSSC.2014.2298456

• Audio amplifier
• class-D amplifier
• direct battery hookup
• efficiency
• feed-forward path
• headphone amplifier
• linearity
• noise cancellation
• power-supply rejection ratio (PSRR)
• supply ripple cancellation

This paper presents a feed-forward power-supply noise cancellation technique to achieve high power-supply rejection ratio (PSRR) in single-ended class-D audio amplifiers. To show the effectiveness of the technique, it is implemented on a first-order single-ended pulse-width modulation (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 methodology, implementation, and trade-offs for the proposed technique are provided. The fabricated class-D audio amplifier achieves a PSRR of 83 dB at 217 Hz, THD+N of 0.0149%, and a maximum efficiency of 94.6% from a 1.8-V power supply. Experimental results show a PSRR improvement of 33 dB from 20 Hz to 20 kHz compared to a similar amplifier designed without the technique. The prototype was implemented using 0.18-mu m CMOS standard technology, and occupies a total area of 0.121 mm(2). The total quiescent power consumption was 356 mu W. The feed-forward power-supply noise cancellation technique enhances single-ended structures to achieve a PSRR performance comparable to differential architecture, and at the same time it consumes small quiescent power with a reduced active silicon area overhead.

• 出版日期2014-3