Bandwidth reduction in dynamic load-modulated power amplifiers: control and RF signal expansion, efficiency and linearity trade-offs

This paper presents an experimental investigation of the effect of bandwidth reduction for baseband control signals used in dynamic load-modulated (DLM) amplifiers. Using a low-power reactively DLM architecture operating at 2.35GHz the effect of control signal filtering on efficiency, output power and adjacent channel power ratio (ACPR) of the system is shown for various signal bandwidths. The method is applied on WCDMA and LTE signals showing a degradation of 2-4 percentage points (pp) in efficiency, 0.5dB lower output power and similar ACPR performance for reducing the bandwidth of the control signal by 70%.