Abstract: This paper describes the design and implementation of a low noise,low power,programmable-gain audio power amplifier used as a headphone driver.It obtains a 0.1% THD+N with a 5V power-supply,a 1kHz frequency audio signal,and a 120mW continuous average output power into a 16Ω load.In addition,the gain can be set from +12 to -34.5dB in 32 discrete steps of 1.5dB.The amplifier is used as the core of a programmable gain audio power amplifier for driving headphones.The audio power architecture,the main module circuits of the amplifier design,the test results,and the chip layout are included.Experimental results using a CSMC 0.6μm double poly double metal CMOS process show that the required performance can be obtained.

Key words: audio power amplifier, low noise, low power