Continuous-time delta-sigma modulator

Abstract

A continuous-time delta-sigma modulator includes a loop filter, a quantizer, a finite impulse response (FIR) filter, and a digital to analog converter. The loop filter integrates a difference between an input signal and a feedback signal. The quantizer quantizes a signal output from the loop filter to convert the quantized signal into a digital signal. The FIR filter performs an FIR filtering process on the digital signal output from the quantizer. The digital to analog converter converts a signal output from the FIR filter into an analog signal and outputs the converted analog signal as a feedback signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the priority of Korean Patent Application No. 10-2018-0068451, filed on Jun. 14, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.BACKGROUNDField[0002]The present disclosure relates to a continuous-time delta-sigma modulator.Description of the Related Art[0003]A delta-sigma modulator is implemented by a discrete-time manner or a continuous-time manner. A delta-sigma modulator according to the discrete-time manner stores or transmits an input signal to a capacitor in the form of charges, based on a switched capacitor technique. The discrete-time delta-sigma modulator operates for the input signal in accordance with a sampling process, but a continuous-time delta-sigma modulator may operate for the input signal without performing a sampling process.[0004]As compared with the discrete-time manner, according to the continuous-time manner, a design requirement...

AI Technical Summary

Benefits of technology

[0009]Another object to be achieved by the present disclosure is to provide a continuous-time delta-sigma modulator which is capable of removing an aliasing error caused by a parasitic capacitor generated in a chopper circuit.

[0013]Desirably, the continuous-time delta-sigma modulator may further include a chopper circuit which is located at a front-end or a rear-end of the transconductor and removes a low frequency noise of the Gm-C integrator.

[0016]According to another aspect of the present disclosure, a loop filter includes: a transconductor Gm which converts a difference of input voltages input to two differential input terminals Vinp and Vinn into a current and outputs the current; first and second capacitors C which accumulate charges by a current output from the transconductor; and a chopper circuit which is located at a front-end or a rear-end of the transconductor and removes a low frequency noise.

[0018]Further, according to the present disclosure, an FIR filter is used so that an input range of the modulator is increased and an aliasing error due to the parasitic capacitor generated in a chopper circuit may be removed.

Problems solved by technology

In the case of a loop filter using a Gm-C integrator, due to a characteristic of an open loop, an input node of an amplifier is not caught as a virtual ground, so that it is difficult to obtain a broad input voltage range and a good linearity.

This may limit an input range and the linearity of the continuous-time delta-sigma modulator.

Images