Cross Post-distortion Balanced Power Amplifier

Abstract

In this paper, we propose a new distortion cancellation mechanism for a balanced power amplifier (BPA) structure using the carrier cancellation loop of a feedforward (FFW) and post-distortion (PoD) technique. We use the distortion generated within a portion of a BPA to cancel the distortion generated within the whole BPA. Samples of the signal and distortion from one part of the BPA are combined with a reference signal, and then those signals destructively combine to generate the error signal. When the error signal is injected into the output of another part of the BPA with the gain and phase control, the distortion generated by both part of the BPA are cancelled. The operating frequency bands of the implemented cross PoD BPA is the IMT-2000 (f0 = 2.14 GHz) band. With the commercial high power amplifier of 240 W PEP for base-station application, the adjacent channel leakage ratio (ACLR) measurement with WCDMA 4FA signal shows 18.6 dB improvement at an average output power of 40 dBm.