Design of Σ-ΔDAC based on oversampling technology

An oversampling Σ-Δmodulator based on quantization noise shaping Sigma-delta(Σ-Δ)modulation of the audio DAC is presented in this paper. It improves the resolution and the signal to noise(SNR) in the baseband. The key point is to provide a detail analysis for the Σ-Δ design, and also gives the correlate structure with the circuits and simulations. An experimental product had been fabricated in TSMC 0.18μm CMOS technology, with the clock frequency of 6.144MHz,the modulator achieves a 128.6dB dynamic range and a signal to noise of 109.5 dB ,the total distortion ratio of -117.2dB.