Multi-Mode Sigma-Delta ADC Switching for Better Common-Mode Rejection
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Solution Overview
Problem
Sigma-delta ADCs with single-ended inputs face suboptimal common mode rejection (CMR) performance, particularly in applications with longer wires or adaptive active noise canceling, which increases power consumption and noise interference.
Innovation Solution
A multi-mode sigma-delta ADC circuit that includes operational transconductance amplifiers (OTAs), a filter, a quantizer, and a differential digital-to-analog converter (DAC), with a controller to switch between single-ended, pseudo-differential, and full-differential operational modes to enhance CMR performance by controlling the OTAs, allowing better noise rejection and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a single-ended input is used with ground as differential input, then the circuit achieves high integration and low power consumption, but the common mode rejection (CMR) performance is suboptimal
Solution Approach 1:
The patent implements a multi-mode sigma-delta ADC circuit that can dynamically switch between single-ended operational mode and pseudo differential operational mode. The controller selectively enables or disables specific OTAs based on the operational mode, allowing the circuit to adapt its configuration. This dynamic reconfiguration enables the system to achieve optimal CMR performance when needed while maintaining low power consumption in single-ended mode, thus resolving the contradiction between power efficiency and common mode rejection performance.
2Measurement precision
If a pseudo differential mode is implemented to improve CMR performance, then common mode rejection improves, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent designs a multi-mode sigma-delta ADC circuit where the same hardware infrastructure (OTAs, filter, quantizer, DAC) serves multiple operational modes. The controller manages both single-ended and pseudo differential modes using the same core components, eliminating the need for separate circuit implementations. This multi-functional design achieves improved CMR performance through pseudo differential mode while avoiding the complexity of maintaining entirely separate circuit paths, as the same components are reused across different operational modes.
3Object-affected harmful factors
If longer wires or cables are used with adaptive active noise canceling, then noise rejection improves, but power consumption increases
Solution Approach 1:
The patent implements a multi-mode sigma-delta ADC circuit that can dynamically switch between single-ended operational mode and pseudo differential operational mode. The controller selectively enables or disables specific OTAs based on the operational mode, allowing the circuit to adapt its configuration. This dynamic reconfiguration enables the system to achieve optimal CMR performance when needed while maintaining low power consumption in single-ended mode, thus resolving the contradiction between power efficiency and common mode rejection performance.
Data Source
AI summary
Embodiments of multi-mode sigma-delta analog-to-digital converter (ADC) circuits and a microphone circuit are disclosed. In an embodiment, a multi-mode sigma-delta ADC circuit includes a pair of operational transconductance amplifiers (OTAs), a filter connected to the pair of OTAs, a quantizer connected to the filter, a differential digital-to-analog converter (DAC) connected to the quantizer, and a controller configured to switch the multi-mode sigma-delta ADC circuit between a single-ended operational mode, a pseudo differential operational mode, and a full differential operational mode to improve common mode rejection (CMR) performance by controlling the pair of OTAs. An output of a microphone and a differential output of the differential DAC are inputted into input terminals of the pair of OTAs.