High Efficiency RF Power Amplifiers with Dynamic Biases for TD-SCDMA Systems

This paper presents a design approach for high efficiency RF power amplifiers with dynamic biases for TDSCDMA systems. The design principle of a PA with dynamic bias is described in detail. The improvement of the power-added efficiency (PAE) is achieved by the drain bias control technique according to the variation of the input power. The simulation results illustrated that this PA can achieve high power-added efficiency, which presents 5% and 10% enhancement, respectively, compared to the conventional amplifiers at 2.0175 GHz of TD-SCDMA frequency when the input power changes. Furthermore, the average efficiency calculated according to the power added efficiency and the probability density of the one-carrier TD-SCDMA signal has been improved nearly 5%, from 20% to 25%.