1-비트 4차 델타-시그마 변조기법을 이용한 D급 디지털 오디오 증폭기

초록

In this paper, we present the design of delta-sigma modulation-based class-D amplifier for driving headphones in portable audio applications. The presented class-D amplifier generates PWM(pulse width modulation) signals using a single-bit fourth-order high-performance delta-sigma modulator. To achieve a high SNR(signal-to-noise ratio) and ensure system stability, the locations of the modulator loop filter poles and zeros are optimized and thoroughly simulated. The test chip is fabricated using a standard 0.18㎛ CMOS process. The active area of the chip is 1.6㎟. It operates for the signal bandwidth from 20㎐ to 20㎑. The measured THD+N(total harmonic distortion plus noise) at the 32Ω load terminal is less than 0.03% from a 3V power supply.

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