Experimental Demonstration of E-Band Tunable Analog Predistortion

Journal article, 2025

A novel stand-alone generic analog predistortion (APD) MMIC is fabricated, implemented, characterized, and experimentally demonstrated at E-band (72.78 GHz). The APD has a wide-range tunability of both the fundamental and the 3rd-order coefficients, mapping directly in predistortion functionality to a 3rd-order memoryless polynomial digital predistortion (DPD) solution, with the output bandwidth of 62–84 GHz. Thus, the proposed APD topology takes the form of a stand-alone and generic module, suitable for the predistortion of different E-band power amplifiers (PAs). System-level characterization is performed using 16-QAM 250-MHz wideband modulated signals, following the ETSI spectral mask standard. Performance is measured through the mask-breaking output power (MBOP), error-vector magnitude, and normalized mean-square error (NMSE). Improvements of up to 3 dB in MBOP are observed. In addition to a demonstration of the tunability of the APD, the system performance comparison between implementations with a stand-alone APD, a stand-alone DPD, and a cascade of DPD and APD is provided. It is experimentally shown that with the advantage of an APD, similar predistortion performance to the counterpart DPD can be achieved.