Multi-level Waveform Generator with Delay Control for Low Distorted Class D Amplifiers

Keywords: Class D amplifier, delay control, low harmonic distortion, multi-level waveform

Abstract

A multi-level waveform generator with delay control is proposed for improving total-harmonic distortion of class D amplifiers. The voltage-mode class D amplifier is a circuit that amplifies the output voltage at the load to be twice almost the power supply voltage by using an input driving signal. The conventional 3-level class D amplifier generates a lot of harmonics due to the switching operation, and the harmonics can only be removed by the frequency response characteristics of the load. A configuration of the class D amplifier that sets an intermediate voltage level to reduce the harmonics has been presented, but it is required to generate the driving waveform for this. The proposed waveform generator makes driving signals that can change the voltage applied to the amplifier load from three to five levels. The generated step time can be optimally set depending on the driving frequency by controlling the RC delay circuits in the edge detector of the proposed generator. The generator IC fabricated in the area of 840 µm × 640 µm using the TSMC 0.25 µm CMOS process shows 5-level driving waveforms converted the input pulse-width modulation signal of 200 kHz. The measurement results show that the intermediate step time can be adjusted to 0.48 µs by controlling the delay circuit of the proposed waveform generator.

Author Biographies

Moon Jeong Lee, Department of Electronic Engineering, Yeongnam University

Moon Jeong Lee received the B.S degree in electronic engineering from Yeungnam University, Gyeongsan, Korea, in 2020. Her research interests include RF/analog integrated circuits and sub-terahertz detectors.

Ha Neul Lee, Department of Electronic Engineering, Yeungnam University

Ha Neul Lee received the B.S degree in electronic engineering from Yeungnam University, Gyeongsan, Korea, in 2019. Her research interests include sub- terahertz imaging systems and high- speed control circuits for detector arrays.

Ui Gyu Choi, Department of Electronic Engineering, Yeungnam University

Ui-Gyu Choi received a B.S. and M.S. degree in electronic engineering from Yeungnam University, Gyeongsan, Korea, in 2018 and 2020, respectively, where he is currently pursuing the Ph. D. degree in electronic engineering. His research interests include Millimeter-wave/terahertz circuits Transmitter IC.

Published
2021-04-01
Section
Articles