The Design Of 4 Channels Class-AB Audio Power Amplifier

The research of audio power amplifier is a hot field of integrate circuit all the times. In the design of audio power amplifiers we mind the perfection. However, the simplest circuit sometimes provides the most appropriate project. Now more and more production of amplifiers with low power loudspeaker show the trend to develop class-D audio power amplifier, but class-AB audio power amplifiers have preponderant all the same in lower price, lower distortion, lower noise.Based on bipolar technology, a 4-channel audio power amplifier used in TV- loudspeaker has been presented in this study, which providing 1W~50W output, 35% efficiency, and THD<1%. The chip also has the following features: open loop gain of 70dB, close loop gain of 26dB; current capability of 2A, slew rate of more than 10V/μs and power bandwidth of 40 kHz. This system of audio power amplifier contains mode change function which controlling channels standby or mute. There has a sensor in the chip, which turning on the protect circuit to shut down the power stage when the temperature of the whole chip is 150 cor the temperature of part area is 180 c.Design of each block is described in detail, layout consideration is also presented in brief and the simulation waves are given.The 3μm High Voltage Bipolar process is used to fabricate this chip. We use Cadence Spectre to run simulation, and results of system simulation indicate that the performance of this circuit meets exactly with the design goals. Meanwhile, we use Cadence Virtuoso to edit layout.