Research And Design Of SiGe BiCMOS Power Amplifier For Wireless LAN Applications

PA is the most important RF front-end module and the largest energy consumer among all the components in wireless communication systems.High peak-to-average ratio(PAR) complex modulation signal is usually demanded in modern wireless communication systems to improve the channel capacity and transmission rate. Also battery life is a key factor for the utility of portable devices. Driven by the demands of lower cost, smaller size and lower power consumption, the fully integrated PA emerges.In the initial years for radio frequency power amplifier (RPIC PA), PAs based on GaAs/Inp III-V material are completely dominant. But these PAs are hard to be integrated with other circuit in a single chip. In recent years, SiGe BiCMOS technology has got gradual improvement in device's cutoff frequency, working voltage and power density, because the CMOS process has been more mature and SiGe epitaxy technology has improved greatly. To reduce RF system cost, improve its compatibility for the demanding of multi-mode and multi-band applications, SiGe BiCMOS RFIC PA achieves more and more attention and becomes a hot pot.The research work is based on the newly-built0.18um SiGe BiCMOS process in China. In this dissertation, the modeling of power cell and the PDK data are improved firstly. Then two samples of2.4GHz and5GHz PAs for Wireless-LAN application are studied and verified in the domestic SiGe BiCMOS process. The main work attributions of this thesis are as follows:1) Four kinds of power cell are proposed for the demanding of PAs for Wireless-LAN applications. SiGe HBT nonlinear equivalent circuit is analyzed according to Volterra series and power cell layout are thermally optimized. The effects of harmonic nonlinearity parameter are evaluated. Also the power cells are tested under both DC and RF condition, The measurement results also provide the critical data of the power cell library and lay the technical foundation for PA design.2) A new temperature stabilization design is proposed in the PA's base biasing path based on the comparison of base-ballasting and emitter-ballasting methods. The design is comprised of parallel resistor and capacitor, preventing thermal runaway effectively and almost causing no insert loss or RF power penalty.3) The effect of bondwire upon PA is assessed.Three-dimensional physical models of bondwire are built in HFSS and analyzed by the finite element method. Equivalent circuit is established and parameter is extracted in different physical models. The insert loss of serveral bondwire is evaluated by testing on PCB.4) A fully-integrated2.4GHz PA is implemented which includes all the matching, biasing and power circuits for the demanding of Wireless-LAN802.11b/g protocol. With the diode-based negative feedback dynamic biasing technique, a linearization and temperature-stable bias circuit is proposed. The measurement results show that the PA has a power gain of22dB, OP,dB of19.6dBm and PAE of20%.5) A dual-band PA with3-stage single-ended common-emitter topology is designed for supporting both2.4GHz and5GHz WLAN applications. A varactor-based adaptive biasing circuit with regulating bias current function is designed, which reduces the average DC power consumption of PA and improves its output1dB power. The test results indicate that the PA achieves a power gain of27.2dB, OP1dB of25.5dBm and PAE of26.1%in the2.4GHz band and a power gain of22dB, OP1dB of21.1dBm and PAE of20.2%in the5GHz band.This dissertation work is supported by the National key project "Core Electronic Devices, High-end General Chips and Basic Software", subtitle of,"Embedded Multi-mode, Multi-band Transceiver Hard Core of Key IP"(No.2009ZX01034-002-002-001) and Shanghai International Cooperation Foundation,"SiGe BiCMOS RF front-end Design of Key Integrated Circuits"(No.09700713800)...