Design And Simulate Of A Linear Dual Band Power Amplifier For GSM900and DCS1800Application

With the widely application of the third generation mobile communicationstandard, the development of kinds of wireless standards put forwards newrequirements of multimode and multi-frequency to RF integrated circuits. This paperanalysis the main performance indicators in detail, designs a dual band poweramplifier for mobile communication standard GSM900and DCS1800.Firstly, this paper analysis the theories and technical indicators of the RF poweramplifier circuit, mainly discusses theoretically the feasibility of the dual band poweramplifier, analysis and simulation method and train of thought.Secondly, this paper carries out the theoretical design of a dual band poweramplifier, including the selection of power amplifier transistors and dielectricsubstrate, and the designation of impedance matching circuits. It uses simple RLCresonant networks as input and output impedance matching circuits, with tworesonance frequency points at0.9GHz and1.8GHz, so as to realize poweramplification under double frequency. Then it uses load-pull and source-pull methodcombining with smith chart tool to complete the inter-stage impedance matching.Thirdly, it completes the overall circuit simulation of the designed poweramplifier using the simulation software ADS2009, and then completes theoptimization of each performance index.Finally, it carries out some research on linearization technology of poweramplifier, and uses capacitance feedback method to improve the linearity in the end.Through the above theoretical design and simulation, this paper designs a dualband power amplifier which meets the requirement of mobile communication standardGSM900and DCS1800.Its output power can be up to34.6dBm and31.6dBm, itspower gain can be up to21dB and12dB at0.9GHz and1.8GHz, and its VSWR issmaller than1.5, showing certain advantages comparing with some other designs.