ADC Gain Balancing for Wider Dynamic Range and Lower Noise
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Solution Overview
Problem
Existing analog-to-digital converter (ADC) systems face challenges in achieving dynamic range enhancement due to issues like gain synchronization and mismatch between analog and digital domains, which affect signal fidelity and noise floor, particularly in audio applications.
Innovation Solution
The proposed solution involves a circuit and method where all gain adjustments occur entirely in the analog domain, either by matching the gain of a programmable gain amplifier (PGA) with the ADC or by eliminating the PGA and using a fixed-gain amplifier, ensuring seamless gain balancing without digital domain interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a programmable gain amplifier (PGA) is inserted before the ADC to amplify low-amplitude signals, then the dynamic range of the ADC is improved, but gain synchronization and gain mismatch issues arise between analog and digital domains
Solution Approach 1:
The patent extracts the gain adjustment functionality from the analog domain (PGA) and relocates it entirely to the digital domain. By removing the PGA and implementing gain control through digital signal processing after ADC conversion, the system eliminates the sources of gain synchronization and mismatch problems while preserving dynamic range enhancement capabilities through digital gain application.
Solution Approach 2:
The patent replaces the mechanical/analog PGA system with a digital gain implementation. Instead of using analog components that suffer from synchronization and mismatch issues, the system uses digital multiplication or scaling operations performed on the digitized signal, thereby substituting an analog mechanical system with a digital computational system that avoids these problems.
2Adaptability or versatility
If the gain of PGA is changed dynamically depending on input signal level, then the dynamic range is enhanced, but gain mismatch and synchronization issues occur between analog and digital gains
Solution Approach 1:
The patent extracts the dynamic gain adjustment functionality from the analog PGA and implements it entirely in the digital domain. By removing the analog PGA, the system eliminates gain mismatch issues between analog and digital domains while preserving the ability to dynamically adjust gain based on input signal levels through digital signal processing.
Solution Approach 2:
The patent changes the domain in which gain adjustment is performed, transitioning from analog parameter adjustment (PGA gain) to digital parameter adjustment (digital gain multiplication). This parameter change allows dynamic gain adaptation to be achieved through digital coefficients or scaling factors, avoiding the precision and matching problems inherent in analog implementations.
3Reliability
If all gain adjustments occur in the analog domain by matching PGA gain with ADC gain, then gain synchronization issues are eliminated, but the system complexity increases
Solution Approach 1:
The patent extracts the PGA component entirely from the system, removing the analog gain adjustment stage that caused synchronization and matching issues. By eliminating the PGA, the system reduces circuit complexity while maintaining gain synchronization through purely digital gain control applied after ADC conversion.
Data Source
AI summary
Described herein is an apparatus and method for enhancing the dynamic range of an analog-to-digital converter (ADC). In one embodiment of the present approach, an analog input signal is amplified in a programmable gain amplifier (PGA) before the ADC receives the signal, so that the gain applied to an input signal, and gain (or attenuation) later applied in order to balance the overall gain of the circuit, occurs only in either the analog domain; in the prior art, gain occurs partly in each domain. The ADC gain is then adjusted to compensate for gain of the PGA and balance the overall gain of the circuit. In another embodiment, the ADC gain is adjusted, and gain of a digital gain element that receives the signal from the ADC is adjusted to compensate for the ADC gain and balance the overall gain of the circuit, eliminating the need for a PGA.