Digital Shaping and Linearization of a Dual-Input Load-Modulated Balanced Amplifier

This paper presents shaping and linearization techniques to trade-off linearity and power efficiency in a dual-input pseudo-Doherty load-modulated balanced amplifier (PD-LMBA). The proposed shaping function is defined to operate in the frequency domain and it is oriented at exploiting the dual-input architecture of the PD-LMBA to either enhance linearity or power efficiency. In addition, since the linearity requirements are not met by simply shaping the input signals, digital predistortion (DPD) linearization is applied on top of it. Experimental validation of the proposed shaping function and DPD linearization is provided for a PD-LMBA excited with 200 MHz bandwidth 5G-like modulated signals with 8 dB of PAPR. For an output power around 40 dBm, the PD-LMBA presents a power efficiency around 50%, while meeting the linearity specs of -45 dB of adjacent channel power ratio (ACPR) and error vector magnitude (EVM) below 3%.