Single-Ended CTSD ADC Input Stage With Common-Mode Error Cancellation
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Solution Overview
Problem
Current ADC technologies face challenges in designing low-noise, high-accuracy single-ended input stages for continuous-time sigma-delta (CTSD) analog-to-digital converters, particularly when handling single-ended analog signals, as they often require external circuitries for conversion to fully differential signals, increasing cost, power consumption, and complexity.
Innovation Solution
The implementation of a common-mode amplifier in the input stage of a single-ended CTSD ADC to convert single-ended input signals into differential signals upstream of the input switches, canceling nonlinear errors and eliminating the need for external conversion circuitries, thereby reducing noise and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external conversion circuitries are used to convert single-ended signals to fully differential signals, then signal conversion accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the signal conversion function into the main ADC input stage by integrating a differential generation circuit directly at the input. This combines multiple functions (single-ended to differential conversion and ADC operation) into a unified structure, eliminating the need for separate external conversion circuitries while maintaining signal conversion accuracy.
Solution Approach 2:
The input stage of the ADC is designed to perform multiple functions: it directly converts single-ended input signals into differential signals while simultaneously performing the ADC conversion function. This multi-functional design eliminates the need for dedicated external conversion circuitries, reducing overall device complexity.
2Measurement precision
If external conversion circuitries are used to convert single-ended signals to fully differential signals, then signal conversion accuracy is improved, but power consumption increases
Solution Approach 1:
The patent merges the signal conversion function into the main ADC input stage by integrating a differential generation circuit directly at the input. This combines multiple functions (single-ended to differential conversion and ADC operation) into a unified structure, eliminating the need for separate external conversion circuitries while maintaining signal conversion accuracy.
3Reliability
If fully differential circuits are used to achieve power supply rejection and immunity to non-ideal effects, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the ADC architecture into a single-ended input path that directly feeds into the differential processing stages. By maintaining the differential internal structure for reliability while providing a simplified single-ended input interface, the design achieves power supply rejection and immunity to non-ideal effects without requiring complex external conversion circuitries.
Data Source
AI summary
Systems, devices, and methods related to low-noise, high-accuracy single-ended continuous-time sigma-delta (CTSD) analog-to-digital converter (ADC) are provided. An example single-ended CTSD ADC includes a pair of input nodes to receive a single-ended input signal and input circuitry. The input circuitry includes a pair of switches, each coupled to one of the pair of input nodes; and an amplifier to provide a common mode signal at a pair of first nodes, each before one of the pair of switches. The single-ended CTSD ADC further includes digital-to-analog converter (DAC) circuitry; and integrator circuitry coupled to the input circuitry and the DAC circuitry via a pair of second nodes.