J. Desai, I. Deligoz, S. Kiaei, and B. Bakkaloglu (USA)
power amplifiers, software defined radio, DC-DC converter, polar modulation, RF transmitter
Software-defined radio (SDR) is a rapidly evolving technology that offers reconfigurablilty and interoperability in radios, but poses challenges in designing highly efficient, programmable hardware modules. The RF front-end transmit path, specifically the power amplifier (PA), is one of the major bottlenecks in SDR implementations, as current state-of-the-art power amplifiers cannot support the modulation bandwidths and dynamic range required to implement SDR systems in low-power wireless handsets. This work presents a polar modulated SiGe CMOS class-E power amplifier with switch-mode supply modulator (SMPS) that is designed for an RF frequency near 900MHz and a variable envelope BW from baseband to 10MHz. The output filter of the SMPS is eliminated in order to implement the Class E PA and supply modulator on the same chip and reduce the number of filter banks required for SDR applications. The envelope dynamic range is 16dB with an ACPR of 43dBc for a GSM/EDGE waveform. The maximum PA efficiency with constant supply voltage is 62%. When operating the supply modulator with a switching speed of 4.3MHz at 50% duty cycle, the system efficiency is 41%.
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