ADC Background Calibration for Gain Error Without Downtime
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Solution Overview
Problem
Analog-to-digital converters (ADCs) face challenges in maintaining accuracy due to variations in gain caused by temperature and manufacturing process variations, leading to errors and non-linearity in output samples, often requiring offline calibration that renders the ADC inoperable during the process.
Innovation Solution
The ADC is calibrated using a background process that allows it to operate continuously by incorporating additional comparators and a random number generator to measure the gain of the analog stage during operation, enabling accurate sample generation without taking the ADC offline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ADC is taken offline for calibration, then gain accuracy is improved, but availability and productivity deteriorate
Solution Approach 1:
The patent performs calibration measurements during normal operation by preliminarily establishing measurement modes where the analog stage processes both calibration signals and actual input signals. The gain is measured in advance using calibration signals while the ADC remains operational, eliminating the need for offline calibration and maintaining continuous availability.
Solution Approach 2:
The patent enables continuous operation during calibration by implementing a measurement mode that allows the analog stage to continuously process signals. The system alternates between calibration measurement modes and normal operation modes without taking the ADC offline, ensuring uninterrupted useful action while maintaining gain accuracy.
2Measurement precision
If additional components are added to the signal path for calibration, then gain measurement capability is improved, but device complexity and performance deteriorate
Solution Approach 1:
The patent makes the existing analog stage and signal path multi-functional by enabling it to process both calibration signals and actual input signals. The same analog stage performs dual functions: normal signal conversion and gain calibration measurement, eliminating the need for separate calibration hardware and reducing overall device complexity.
Solution Approach 2:
The patent implements self-service calibration where the ADC uses its own internal resources (analog stage, signal path) to perform gain measurements. The system calibrates itself without requiring external calibration equipment or additional dedicated calibration components, reducing complexity while maintaining measurement capability.
Data Source
AI summary
An analog-to-digital converter (ADC) includes an analog input stage including an output configured to generate an analog output signal and a digital stage coupled the output of the analog input stage. The digital stage is configured to classify the analog output signal into one of a plurality of consecutive voltage ranges. Responsive to the analog output signal being classified in a first enumerated voltage range of the plurality of voltage ranges during a rotation of a sample, a voltage for a subsequent rotation is determined as if the analog output signal is classified into a non-enumerated voltage range selected according to a state of a random number signal.