Alternate Diagnostic Testing and Compensation of RF Transmitter Performance Using Response Detection

Digital predistortion is used as a compensation technique in communication systems to minimize the effect of power amplifier non-linearity while increasing its operational efficiency. Prior linearization schemes use the receiver chain to feed data to the baseband processor that adaptively adjusts the predistortion coefficients. The procedure is iterative, requires many test applications, is sensitive to receiver quality, and is not suitable for RF communication front ends in which the mixer, LNA and PA are dynamically reconfigured to adapt to changing operating conditions. In the proposed scheme, a single multi-sine diagnostic test is applied from the baseband, and the response of the transmitter is captured via a response envelope detector. A novel unified methodology for co-tuning predistortion coefficients along with the PA bias voltage based on response diagnosis is proposed, thereby, enabling the transmitter to operate at high efficiency and linearity.