Experimental Demonstration of E-Band Tunable Analog Predistortion

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