Ku-band Mmic Power Amplifier

This paper mainly introduce the circuit design of Ku band HEMT transistor MMICpower amplifier, the design process of topology structure,bias circuit,matching circuit andthe power combining and dividing network are all described in detail. The theory ofTwo-Dimension Electronic Gas(2DEG) about the HEMT is introduced; the characteristicsof HEMT are described including current-voltage, capacity-voltage and small/large signalbehavior. Also, the characteristic and technology of MMIC power amplifier are researched.A Ku-band MMIC power amplifier based on 0.25μm GaAs HEMT process isdesigned. The amplifier is composed of three-stage as gain-stage, driver-stage and outputpower stage. The first stage HEMT with gate width of 6×120μm was used to drive thesecond stage HEMT with gate width of 8×160μm, the output stage has the same gate widthand numbers as the second stage; the chip size is 2.55mm×1.57mm. With double DCpower supply for the drain and the gate, the amplify works at class-A operation for optimalpower output with minimal distortion. In the output stage, a new structure of powercombing and dividing network which is transform from the Wilkinson network andstraightly divide the input power into four-way is used, The power amplifier has27.3±0.2dB small-signal gain with input and output VSWR less than 1.5, The output powerat 1dB gain compression are more than 34.8dBm and Pout is more than 36.7dBm from 13to 14 GHz. Input and output ports all match to 50ohm. In conclusion, analysis of thesimulation results satisfied all requirements, at the same time, these results evidentlyverified the feasibility and reliability of the design conception.