Research And Design Of SiGe BiCMOS Power Amplifier For WLAN 802.11b/g

Wireless communication is developing day by day, which is in relation to several fields not only as national defense, scientific research, medical treatment, industry, but also as daily communications, shopping, entertainment, traffic, etc. Low-frequency communications become more and more powerless as the application fields getting wider and the performance needs getting higher, so the radio-frequency technology becomes the key point of research.Power amplifier is one of the most important components in the radio-frequency system, so that the performance of the whole wireless transceiver system is depended on the performance of the power amplifier. There are several institutes and companies carry out research on design and produce of power amplifier. In this article, we advanced a design of SiGe BiCMOS power amplifier for WLAN 802.11b/g (2.4GHz), completed the test and got a good performance.The research work and contribution in this article includes:1) Advanced a structure of class A high-linearity power amplifier consists of two amplifying stages. Designed the bias circuits of two stages and three impedance matching networks. The bias circuits used the temperature insensitive current-mirror structure. For the impadence matching network, we used the T-shape network which has high flexibility and small area, and the matching performance was good.2) Designed the layout based on 0.18um SiGe BiCMOS technology independently, all the devices are on-chip. Optimized the grounding of the emitter of the two transistors, and used the tree-shaped layout structure in the metal connection between collectors of the two amplifying transistors and impedance matching networks, so that the large current could transfer smoothly.3) Completed the on-wafer measurement and the circuit showed a good performance. Sll and S22 are -17dB and -30dB separately, so that the input port and output port matched well. And the maxmum output power is 24dBm at 4V supply, which exceeds the design index.4) Additionally, in order to investigate the circuit well, the schematic and layout with package model were designed, and measured the packaged chip.