A Novel DAC Based Switching Power Amplifier for Polar Transmitter

A novel switching power amplifier based on the concept of digital to analog converter (DAC) is presented for polar transmitter architecture. The novel idea in this amplifier is to generate a current proportional to the amplitude modulation signal and the power control bits. The current is then up-converted to the frequency of interest using switching transistors. In this paper, we demonstrate that the performance of the proposed circuit is superior compare to the existing power amplifiers designed for polar transmitter. The measurement results show maximum output power of 27.8dBm with power efficiency of 34%. Moreover, the amplifier exhibits amplitude modulation bandwidth of 4.2MHz and 62dB power control dynamic range. The circuit is fabricated in CMOS 0.18mum process with 3.3V power supply