The Design Of Class AB Audio Power Amplifier

With the improvement of technology,Power Integrated Circuits(PIC) gets rapid development.PIC is a single chip including high voltage power devices and controlled ICs. Audio power amplifier is an important part of PIC which is widely used in consumer electronic products,and China is the most important market of consumer products and the biggest world manufacture center of the consumer products.We launch a reach on audio power amplifier.In this paper,a class AB folded-cascade CMOS power operational amplifier with stable open-loop gain is presented.First,the advantages and disadvantages of kinds of power amplifiers are introduced;a proper selected folded-cascade amplifier structure is used in order to satisfy the design target.Second,the input stage with double inputs and double outputs deferential amplifier circuit,the voltage amplifier stage,And the complementary symmetry push-full power output stage circuit are designed.The assistant circuits included mute of audio power amplifier and bias circuit.And then by using the method of power and current budget,appropriate device parameter is received.The simulated result shows that the 0 dB gain-band with is 100 KHz,the quiescent supply current is 4mA.The output stage delivers maximum 41mA into a 32Ωload and the power is 85mW for 32Ω,THD+N is less than 0.1%.The amplifier exhibits a 93.8dB open-loop gain at low frequency,1.31V output at a 5V supply in a 0.6μm CMOS technology.On the other hand,in order to improve the input range of the amplifier,a complementary folded-cascade operational amplifier is submitted.At last,0.61μm,N-well,Silicon-gate and double-layer metal are used in CMOS layout design.PMOS transistor and NMOS transistor with big dimension using parallel connection transistors structure,share the same drain region and source region,which makes the system's area even more economic.