Integral analogue-to-digital converter and sampling control method thereof

Abstract

The invention relates to an integral analogue-to-digital converter and a sampling control method thereof. The converter comprises an integrator, a comparator and a down-sampling filter which are sequentially connected, and also comprises a logic control circuit, an input sampling circuit and a feedback sampling circuit, wherein the input end of the logic control circuit is connected with the output end of the comparator on the one hand, and is connected with the output end of the comparator through a negation gate on the other hand, and receives a first input control signal and a second input control signal input from the outside and outputs a first feedback control signal and a second feedback control signal for controlling the feedback sampling circuit. The logic control circuit is arranged to control alternate opening and closing of each sampling switch in a sampling period, so the sampling speed ratio between the input signal and the feedback signal is lowered, the signal-to-noise ratio caused by overload is finally and effectively lowered and defects of a method for reducing the ratio of input capacitance to feedback capacitance in the prior art are overcome.

Description

technical field [0001] The invention relates to the field of electric energy metering, in particular to an integral analog-to-digital converter used in an analog circuit module of an electric energy metering chip and a sampling control method thereof. Background technique [0002] As we all know, the integral analog-to-digital converter (that is, ΣΔA / D converter) generally adopts oversampling technology, noise shaping technology and digital filtering technology, by pushing a large amount of noise energy to the high frequency outside the signal baseband, and then using digital The filter filters out-of-band noise to obtain very high precision. However, due to the high oversampling, the bandwidth of the signal is limited to a certain extent. Therefore, the ΣΔA / D converter is mainly used in low-speed, high-speed In the field of accuracy, especially in the design of ammeters that require high precision in low bandwidth requirements, they are widely used. [0003] In the prior a...

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Problems solved by technology

But this method actually reduces the ratio of the input capacitance to the feedback capacitance by reducing the input capacitance, that is, on the summing node, the share from the input signal decreases, and the share from the feedback signal increases, due to the input The signal of the integrator is attenuated, thereby reducing the dynamic range of the entire ΣΔA / D converter

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