Delta-Sigma modulator with external disturbance signal

Abstract

The invention discloses a Delta-Sigma modulator with an external disturbance signal. The Delta-Sigma modulator comprises a negative feedback Delta-Sigma modulator module and a noise shaping Delta-Sigma modulator module. The negative feedback Delta-Sigma modulator module is used for transforming an input signal into a pseudo-random output signal, wherein the output signal is used as an external pseudo-random disturbance signal of a post-stage module; and the noise shaping Delta-Sigma modulator module in cascade connection with the negative feedback Delta-Sigma modulator module is used for carrying out noise shaping on the input signal of the whole modulator circuit and outputting a shaped digital signal. According to the invention, with the output of the negative feedback Delta-Sigma modulator module as the external disturbance signal of the noise shaping Delta-Sigma modulator module, the output sequence length of the noise shaping Delta-Sigma modulator is extended effectively, so thatthe smooth output frequency spectrum is obtained and the output ground noises and burrs are reduced effectively.

Description

technical field [0001] The invention belongs to the technical field of signal processing, in particular to a Delta-Sigma modulator using an external disturbance signal. Background technique [0002] In today's digital communication systems, Nyquist sampling technology is gradually replaced by oversampling technology because it is easily affected by component matching, circuit non-ideality, and high-power quantization noise interference. Oversampling refers to sampling the input signal with a frequency much higher than the Nyquist frequency. Since the number of quantization bits remains unchanged, the total quantization noise power remains unchanged, but the power of quantization noise is distributed to more frequency points due to the increase of sampling frequency, so the quantization noise power spectrum in the corresponding signal band The density is reduced, thereby improving the signal-to-noise ratio (SNR, Signal to Noise Ration) of the communication system. However, ...

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Problems solved by technology

However, on the one hand, because the filter order of the disturbance shaping generally cannot exceed 1-2 (1 is the modulator order of the noise shaping MASH DDSM), therefore, if the output signal period of the LFSR is too long, the output of the modulator will be low On the other hand, the output period of the modulator using LFSR perturbation is easily affected by the initial conditions of the modulator itself and the initial conditions of the LFSR itself. If these initial conditions are not set properly, the LFSR perturbation signal will not be effective Extending or even reducing the period of the modulator's output signal

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