Abstract

The pulse-modulated polar transmitter (PMPT) uses radio-frequency (RF) phase modulated signal with pulse-width modulated envelope to drive a power amplifier (PA) as a switch to achieve high linearity and high efficiency. However, as the signal bandwidth increases, various non-idealities limit the performance of the PMPT architecture. In this paper, a Gibbs-phenomenon reduction filter is proposed with a partial Fourier series of digital pulse-width modulation (PWM) such that the pulsed signal is more immune to the distortion in nonlinear high-efficiency RF PAs. For validation, a prototype transmitter was tested with a 20-MHz bandwidth 256-QAM 5G new radio (NR) signal at 2.14 GHz. The proposed method achieved a drain efficiency of 28.3%, error vector magnitude (EVM) of 1.67%, and adjacent channel leakage ratio (ACLR) of -45.4 dBc at an output power of 18 dBm using the prototype transmitter. Linearity requirements for base stations were met without the use of any digital predistortion methods.

Highlights

  • The radio-frequency (RF) power amplifier (PA) has always been the most power-consuming component in a wireless communication system

  • Since the proposed Gibbs-phenomenon-reduced digital pulse-width modulation (GRDPWM) is more immune to PA nonlinearity, the pulse-modulated polar transmitter (PMPT) is able to achieve an adjacent channel leakage ratio (ACLR) of −45.4 dBc, which exceeds the base station linearity specifications for the 5G New Radio (NR) standard without using any digital predistortion (DPD) techniques

  • In this paper, the problems raised by using partial Fourier series (PFS) of digital pulse-width modulation (DPWM) in PMPTs because of Gibbs phenomenon are discussed

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Summary

INTRODUCTION

The radio-frequency (RF) power amplifier (PA) has always been the most power-consuming component in a wireless communication system. Comparison of conventional DPWM, unfiltered and filtered PFS of an envelope signal in the time domain with PWM sampling frequencies fp = 100 MHz. respectively. The Gibbs-phenomenon-reduced digital pulse-width modulation (GRDPWM), which reduces the time-domain ripples in PFS of DPWM by adding the proposed Gibbs phenomenon reduction filter in (25), has the form of EGRDPWM (t) =. Performance Comparison of Conventional IQ signal, DPWM, PFS and GRDPWM

SYSTEM IMPLEMENTATION AND MEASUREMENT
Findings
CONCLUSION

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