SDR transmitter based on LINC amplifier with bias control

This paper describes a LINC (Linear Amplification using Nonlinear Components) handset transmitter adopting DC bias control. The power amplifier is operated at a saturated output power level and its level is adjusted by DC bias control. Thus the transmitter guarantees high efficiency at all usable output power level. Due to the LINC linearization, it can operate as a linear power amplifier. The new LINC transmitter can be used as a transmitter for software defined radio (SDR), since it can efficiently amplify both the GSM type constant envelope signal and CDMA type non-constant envelope signal, and its control part is very simple and mostly embodied in the digital domain. For verification, a 1.71 GHz LINC prototype transmitter has been implemented and tested. The results, compared with conventional cases, clearly show the suitability of the new LINC transmitter for SDR application.