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对Sigma Delta调制与脉冲编码调制进行对比,研究了Sigma Delta调制与脉冲编码调制的优缺点。建立了微加速度计中两位输出的Sigma Delta调制和两位输出的脉冲编码调制的仿真系统。然后,对比使用这两种调制方式的微加速度计的加速度信号,并分析在两种不同调制方式下的输出信号波形的差别。最后,利用周期图法得到了两种调制信号的功率谱密度图,发现在低频段脉冲编码调制信号的量化噪声比Sigma Delta调制信号大很多;而在高频段,两种调制方式信号的量化噪声一样严重。仿真结果表明,尽管Sigma Delta调制系统比脉冲编码调制系统更加复杂,但是Sigma Delta调制得到的信噪比要比脉冲编码调制得到的信噪比高出20dB。
The Sigma Delta modulation and pulse code modulation are compared to study the advantages and disadvantages of Sigma Delta modulation and pulse code modulation. A simulation system of two-output Sigma Delta modulation and two-output pulse code modulation in a micro-accelerometer is established. Then, compare the acceleration signals of the micro accelerometer using these two modulation methods and analyze the difference of the output signal waveforms under the two different modulation methods. Finally, the power spectral density of the two modulated signals is obtained by using the periodic graph method. It is found that the quantization noise of the pulse-coded modulation signal is much larger than that of the Sigma Delta modulation signal in the low frequency band. At high frequency, the quantization noise of the two modulation signals Just as serious. The simulation results show that, although the Sigma Delta modulation system is more complicated than the pulse code modulation system, the sigma-delta modulation obtained by Sigma Delta modulation is 20 dB higher than that obtained by pulse-code modulation.