Low-noise, high-accuracy single-ended input stage for continuous-time sigma delta (CTSD) analog-to-digital converter (ADC)

An input circuitry in an integrated single-ended continuous time sigma delta (CTSD) analog-to-digital converter (ADC) device, the input circuitry comprising:

• a pair of input nodes to receive a single-ended input signal;
• a first signal path coupled to one of the pair of input nodes, the first signal path comprising a first resistor coupled to an input of a first switch via a first node;
• a second signal path coupled to the other one of the pair of input nodes, the second signal path comprising a second resistor coupled to an input of a second switch via a second node;
• and
• a common mode amplifier to inject a common mode current signal to the first node and the second node to provide a differential signal across the input of the first switch and the input of the second switch.

A method for performing a continuous time sigma delta (CTSD) analog-to-digital conversion on a single-ended input signal, the method comprising:

• receiving, at a pair of input nodes, the single-ended input signal;
• converting the single-ended input signal into a differential signal, wherein the converting comprises injecting a common mode signal into inputs of a pair of switches, each coupled to one of the pair of input nodes;
• generating, via a digital-to-analog-converter (DAC), a feedback signal;
• combining the differential signal and the feedback signal to provide a combined signal;
• and
• integrating, via an integrator, the combined signal.