Nonlinear Slope ADC for Transfer Function Linearity
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Solution Overview
Problem
Existing slope analog-to-digital converters (ADCs) fail to accurately convert analog input signals to digital representations over the entire range of possible values due to nonlinearities introduced by components such as input buffers and sampling networks.
Innovation Solution
Implementing a slope ADC with a nonlinear relationship between the slope signal and the counter signal to compensate for these nonlinearities, ensuring accurate conversion across the entire range of input values without the need for digital post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional slope ADC with linear relationship between slope signal and counter signal is used, then the device complexity is low, but the measurement precision deteriorates due to nonlinearities in the transfer function
Solution Approach 1:
The patent applies parameter changes by modifying the relationship between the slope signal and counter signal from linear to nonlinear. Specifically, the counter signal is designed with a nonlinear progression where the increment between consecutive counter values increases with the counter value itself. This parameter transformation compensates for the nonlinearities introduced by the sampling network and input buffers, thereby improving the linearity of the overall transfer function without adding complex external correction circuits
2Measurement precision
If digital post-processing corrections are implemented to compensate for nonlinearities, then the measurement precision improves, but the loss of time increases due to additional processing steps
Solution Approach 1:
The patent implements preliminary action by pre-compensating for nonlinearities in the analog domain through the nonlinear relationship between the slope signal and counter signal. The counter signal is designed beforehand to counteract the expected nonlinear effects of the sampling network and input buffers. This approach performs the correction function during the analog-to-digital conversion process itself, eliminating the need for subsequent digital post-processing operations and thus avoiding time loss
Data Source
AI summary
A slope analog-to-digital converter, ADC, for converting an analog input signal to a digital representation, said slope ADC comprising: a comparator configured to compare two input signals, wherein a sampled value of the analog input signal and a slope signal are used in forming the two input signals; a memory element, which is configured to receive a trigger signal based on the comparator identifying a change in which of the two input signals is higher, and a counter signal, wherein a value of the counter signal when the trigger signal is received provides the digital representation of the sampled value of the analog input signal; wherein the slope signal and the counter signal have a nonlinear relationship, wherein the nonlinear relationship is adapted to improve linearity of a transfer function of the slope ADC for converting the analog input signal to the digital representation.