Burst mode operation as an efficiency enhancement technique for RF power amplifiers

In this paper, the Burst Mode operation is proposed as an efficiency enhancement technique for RF power amplifiers. The essence of the burst mode operation is to modulate the amplitude of the envelope signal into a series of pulses such that the width of the signal burst or the total amount of pulses are varied according to the envelope. The phase information is still contained by the timing of the pulses. This work presents an introduction of the burst mode operation and the efficiency of Burst Mode RF power amplifiers is briefly analyzed. The improvement on the efficiency with a wideband load and a narrow band filter are both illustrated. To demonstrate the validity of the proposed Burst Mode operation, a PCB-mounted Burst Mode PA using a LDMOS transistor has been fabricated. Measurements show a peak efficiency of 78% and 28.5dBm output power and an efficiency of 49.5% at 6dB power back-off.