A Design And Analyse For Class AB Audio Power Amplifier

With the improvement of science and technology level, analog integrated circuittechnology is developing rapidly. Audio power amplifier as an important analogintegrated circuit plays an important role in the daily lives of people. Class Aamplifier distortion is small, but only theoretical efficiency reached50%;Class Bpower amplifier’s efficiency in an ideal case may reach78.5%, but its existence in thecrossover distortion; Class D power amplifier with low power consumption has beenwidely used on many mobile portable products, but the cost is higher. Class ABamplifiers in the pursuit of low cost, low noise, high efficiency, low distortionapplications have stronger competitiveness. Analog integrated circuit design is theembodiment of such a relationship of weigh and compromise.In order to adapt to market demand, this paper designed a four channel class ABaudio power amplifier which is mainly used in car audio, adopts the BTL output stage.Inhibition of pop-noise circuit structure is designed, can better prevent the switchmachine produce crack; Overvoltage protection to prevent the chip when the voltageis high, low-voltage protection can shut off the circuit when the voltage is too low, toprevent the serious distortion of voice signal; overload protection and short circuitprotection circuit will protect the chip from the large current. Chip over temperatureprotection design is clever, over temperature protection starting point stability can beguaranteed in the case of different process corners. These protection circuitseffectively guarantee the stability of the circuit.This chip design according to the requirements of various functional moduleparameters,use the small signal model to theoretical calculation, apply cadencespectre software simulation, the results show that the circuit designed can meet therequirements of various performance indicators, work stability. Circuit has9to18vvoltage range, single channel maximum output power can be up to45w, typicalstandby current is only0.01uA. In this paper the actual circuit use0.35um HHNEC40v BCD process design and simulate, made comprehensive ac simulation, dc simulation and transient simulation, corner simulation. Finally, simulation concludedthat design result can meet the requirements and adapt to market demand.