摘要
A high efficiency class-1 linear audio power amplifier （PA） with an adaptive supply is presented. Its efficiency is improved by a dynamic supply to reduce the power transistors＇ voltage drop. A gain compression technique is adopted to make the amplifier accommodate a single positive supply. Circuit complicity and chip area are reduced because no charge pump is necessary for the negative supply. A common shared mode voltage and a symmetric layout pattern are used to minimize the non-linearity. A peak efficiency of 80% is reached at peak output power. The measured THD＋N before and after the supply switching point are 0.01% and 0.05%, respectively. The maximum output power is 410 mW for an 8 f2 speaker load. Unlike switching amplifiers, the class-I amplifier operates as a linear amplifier and hence has a low EMI. The advantage of a high efficiency and low EMI makes the class-1 amplifier suitable for portable and RF sensitive applications.
A high efficiency class-1 linear audio power amplifier （PA） with an adaptive supply is presented. Its efficiency is improved by a dynamic supply to reduce the power transistors＇ voltage drop. A gain compression technique is adopted to make the amplifier accommodate a single positive supply. Circuit complicity and chip area are reduced because no charge pump is necessary for the negative supply. A common shared mode voltage and a symmetric layout pattern are used to minimize the non-linearity. A peak efficiency of 80% is reached at peak output power. The measured THD＋N before and after the supply switching point are 0.01% and 0.05%, respectively. The maximum output power is 410 mW for an 8 f2 speaker load. Unlike switching amplifiers, the class-I amplifier operates as a linear amplifier and hence has a low EMI. The advantage of a high efficiency and low EMI makes the class-1 amplifier suitable for portable and RF sensitive applications.
基金
supported by the Analog Devices and ASIC Laboratory,China
