Broadband High Efficiency S-LMBA Design

In sequential load-modulated balanced power amplifiers (S-LMBA), an over-driven class-B amplifier is used as the carrier amplifier while the balanced PA pair is biased in class-C mode to serve as the peaking amplifier. The sequential operation greatly extends the high-efficiency power range and enables the PA to achieve high backoff efficiency across a wide bandwidth. This presentation will first introduce the operation principle of S-LMBA and then discuss how waveform engineering can be used to expand the design space to further improve the power efficiency over an extended operation bandwidth.