Design of high-efficiency voltage-mode class-D RF power amplifier for class-S transmitter using signal analysis and additional multi-section bandpass filter

Abstract

This paper proposes a high-efficiency voltage-mode class-D (VMCD) RF power amplifier (PA) for class-S transmitter, which includes additional multi-section bandpass filter (BPF). For an accurate analysis of class-S transmitter, the output signals of band pass delta sigma modulator (BPDSM) are described with probability distribution functions (PDF) versus pulse widths of quantized signals. Usually, the results show that magnitudes of sub-harmonic terms increases for high peak-to-average power ratio signal such as long term evolution (LTE) signal. For a high efficiency and appropriate linearity of class-S transmitter, we propose a VMCD PA utilizing a multi-section BPF. The proposed architecture effectively improves the linearity without deterioration the efficiency. For the LTE signal, the efficiency is 25.82% and adjacent channel power ratio (ACPR) is -52.44dBc when using a one-section BPF. By using the multi-section BPF, ACPR and efficiency have been improved up to 11.88dB and 13.44% respectively. The effectiveness of the proposed design is demonstrated for various input signals. © (2013) Trans Tech Publications, Switzerland.