‘Bang-Bang’ technique in supply modulation for linear wideband RF power amplifiers

Abstract

This paper deals with the design techniques of power efficient switching regulators intended for linear power amplifiers employing envelope tracking techniques in wideband wireless standards. The bottlenecks involve a tradeoff between ripple voltage, slew rate and bandwidth. The slew rate limitation is identified as the main challenge, then a ‘bang-bang’ slew enhancement technique is proposed. This approach enables the use of efficient supply modulators in wideband power amplifiers. The proposed scheme does not significantly degrade PA efficiency and preserves the stability of the switching regulator. The prototype has been implemented using the TSMC 0.18 µm technology; schematic simulation results in Cadence® are presented to prove the concept.