Wcdma Power Amplifier Research And Design

PA (Power Amplifier), which is an important part of transmitter, consumes most parts of transmitter's power. Especially, modern wireless communication has high data rates, the signals have high PAR (Peak Average Ratio), and in order to satisfy signal's specifications, the PAs have even lower efficiency, consuming more power. To enhance PA's efficiency will helps to enhance the transmitter's efficiency, and reduce its power consumption.This paper aims at Doherty high efficiency PA, analyzed and found out the factors which affect DPA's (Doherty PA) efficiency and linearity. Based on these factors(include current ratio, impendency character, single PA's efficiency, single PA's match network, gain, etc.), simulated , practically design and measure the DPA in the WCDMA down link system, and also explained and analyzed these how these factors affects DPA's characters.Based on LDMOS power amplifier MRF21030, began with single PA design, several elements have been quantized their affection to DPA's efficiency and linearity, such as input power division, output offset line and gate voltages. When outputs a 40dBm WCDMA with 9.5dB PAR, LDOMS MRF21030 DPA can reach 36% drain efficiency and ACPR -32dBc. Also CREE's GaN PA CGH40035 has invested to reseach Class-F DPA, with 40dBm output WCDMA, its drain efficiency and reach 52%, 16% enhancement than LDMOS DPA, but ACPR-26, 6dB worse than LDMOS DPA. This paper has not pay much effect on DPA's linearity technology, with Digital Pre-distortion the DPA can be used in real systems.