Design Of Power Amplifier Module And Monolithic Circuit Based On SiGe HBT Technology

The rapid development of wireless communication technology has greatly changed the way of people’s daily communication. As one of the core modules of wireless transceiver, the power amplifier (PA) directly affects the operating efficiency of the transceiver as well as the quality of signal transmission. With the popularization of the 4th Generation mobile communication technology (4G), higher speed of information transmission presents higher requirements to the efficiency and linearity of the power amplifiers, making the design of power amplifier become the emphasis and hot spot of the radio frequency (RF) front end project. For now the PAs fabricated with GaAs and InGaP technology have monopolized the market, but SiGe HBT has the advantages of low cost, high characteristic frequency, good performance on noise and thermal dissipation, which prove that it has vast potential for application in the field of wireless communication.A PA MMIC (Monolithic Microwave Integrated Circuit) as well as a PA module on PCB are designed based on the 0.18 μm SiGe HBT technology in this paper, both of them are used for WLAN domain at 2.4 GHz.The PA MMIC adopts three stages structure to satisfy the demand of power gain, it is biased at AB type working state to balance linearity and efficiency, ballast resistors at the base of transistors are added to enhance the stability of the circuit, and a kind of self-adaptation bias circuit is introduced to improve the linearity and power gain. In order to obtain max output power, loadpull technique is used for the output matching net. The type of matching nets at the input port and between stages is selected with flexibility to achieve best power transmission. The layout of the amplifier is designed with full consideration of parasitic factors and heat dispersion. The final measurement result of the PA shows that:output power at the 1 dB compression point is 23.4 dBm, power gain is about 28.8 dB, and PAE (Power Added Efficiency) is 13.6%.The PA module is composed of three cascade powercells on PCB, and the powercells are chosen depend on the focus of power gain or the output power. The TRL calibration kit is designed according to the measurement PCB, and TRL calibration is used to get the accurate output and input matching impedance of the powercell. The matching networks between stages is the key point of the PA module design. The measurement result shows that, for the 64QAM signal, this PA module attains 18.26 dBm output power with 28.5 dB power gain when EVM reaches 3%, good linearity is realized.