Design of 70W GaN Based Power Efficient Amplifier for Software Defined Radio Applications

In this paper, high power amplifier is designed and developed in 225 MHz to 400 MHz for software defined radio communication. A GaN based high electron mobility transistor is used in printed circuit technology to analyze the structure. A detail design procedure is described including input, output matching and load pull analysis for optimum output power of the transistor. A prototypes is fabricated to validate the proposed design. The measured small signal input return loss is better than 13.2 dB and gain 22.95 dB with a gain variation of +/- 0.95 dB over the band. Similarly, the measured efficiency is better than 60% over the output power of 48.5 dBm. The proposed design achieves EVM performances of less than 3.5% for QPSK modulation having a symbol rate of 250 kS/sec at an average output power of 47.0 dBm over the entire bandwidth. Also, the adjacent channel power ratio is better than -50 dBc across the frequency band.