SAR ADC Feedback Compensation for Temperature-Drift Gain Error
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Analog to digital converters (ADCs) suffer from gain errors due to temperature-induced variations in circuit components, particularly in the bias signals used by digital to analog converters (DACs), leading to undesirable errors in system output.
Innovation Solution
A temperature compensation system that includes a comparator, a SAR module, a detector to sense temperature variations, a look-up table to generate a compensation signal, and a summing node to combine this signal with the feedback signal, effectively mitigating temperature-induced errors in the ADC gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DAC is biased by a temperature-varying bandgap voltage to enable operation, then the ADC can function across different temperatures, but temperature-induced gain error is introduced
Solution Approach 1:
The patent implements a feedback mechanism where the temperature-induced gain error is detected through a detector that monitors the relationship between the input signal and the DAC output. The detected error signal is then fed back to a summing node that adjusts the DAC output to compensate for the temperature-induced gain error, thereby maintaining measurement precision across different temperatures
Solution Approach 2:
The patent changes the biasing parameter of the DAC by introducing a compensating signal that varies with temperature. The summing node combines the original bias signal with a temperature-dependent compensation signal, effectively changing the operating parameters of the DAC to counteract temperature-induced gain variations and maintain accurate conversion
2Measurement precision
If the bias signal is made temperature-stable to eliminate gain error, then ADC gain accuracy is improved, but the complexity of the biasing system increases
Solution Approach 1:
The patent introduces an intermediary compensation signal that mediates between the temperature-varying bias signal and the DAC output. This intermediary signal, generated through the detector and summing node, adjusts the effective bias applied to the DAC, eliminating the need for a completely temperature-stable bias source while maintaining gain accuracy
3Reliability
If temperature compensation circuitry is added to correct gain error, then ADC output reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the temperature compensation function with the existing feedback path of the ADC. The detector, summing node, and compensation signal generation are integrated into the signal processing path, combining multiple functions (error detection, compensation signal generation, and output adjustment) into a unified structure that improves reliability without proportionally increasing complexity
Data Source
AI summary
An analog to digital converter temperature compensation system comprising a comparator configured to compare an analog input signal to a compensated feedback signal and generate a comparator output. A SAR module processes the comparator output to generate a digital signal. A digital to analog converter, biased by a biasing signal having temperature change induced error, is configured to convert the digital signal to a feedback signal and a detector is configured to detect a signal that is proportional to temperature. A look-up table is configured to receive and convert the signal that is proportional to temperature to a compensation signal such that the compensation signal compensates for the temperature change induced error in the biasing signal. A summing node combines the feedback signal with the compensation signal to create a compensated feedback signal.