Hardik Prakash Gandhi

Concurrent dual-band digital predistortion

With a power amplifier (PA) being able to support widely separated frequency bands, dual-band digital predistortion techniques have been proposed as an efficient alternative to traditional wideband digital predistortion by only compensating nonlinear distortions around the signal bands of interest. In this paper, we provide theoretic analysis of the connection between wideband and dual-band memory polynomial models and propose two efficient implementation schemes based on lookup tables. Performance was evaluated with an experimental test setup using a symmetric Doherty PA and a dual-band signal (10 MHz LTE and 2-carrier WCDMA) with 97 MHz center separation. Drain efficiency of 31% was achieved with 41.2 dBm output power and both bands meeting −45 dBc ACLR requirement.

Crest factor reduction for dual-band systems

As wideband power amplifiers (PAs) become more power and cost efficient, supporting widely separated frequency bands with a common PA and transmit chain is becoming more practical. Dual band digital pre-distortion (DPD) techniques have been proposed as efficient alternatives to traditional wideband solutions for such applications. In this paper, we propose a novel dual band crest factor reduction technique that works together with a dual band DPD solution. Theoretical analysis is performed to compare the dual band solution with the traditional wideband solution. Performance of the proposed technique was demonstrated with a dual-band signal that has two 10 MHz LTE bands with edge to edge separation of 200MHz.