PTAT Delta-Sigma Modulator for Temperature-Stable Conversion
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Solution Overview
Problem
Delta sigma modulators are sensitive to temperature variations due to changes in internal resistance and heating in semiconductor materials, affecting the accuracy and stability of analog-to-digital and digital-to-analog conversions.
Innovation Solution
Implementing a proportional to absolute temperature (PTAT) conditioner for both the input and reference signals within the delta sigma modulator, ensuring both signals have the same temperature dependence, which cancels out temperature-induced changes, and using a feedback loop with a digital-to-analog converter (DAC) and loop filter to maintain output stability across a reasonable temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If delta sigma modulators are used for analog-to-digital and digital-to-analog conversion, then high accuracy and wide dynamic range are achieved, but temperature sensitivity and output instability occur due to internal resistance changes and heating in semiconductor materials
Solution Approach 1:
The patent applies parameter changes by transforming the linear input signal into a logarithmic domain where temperature variations have a reduced impact. The logarithmic transformation changes the mathematical relationship between input signal and output, making the system less sensitive to temperature-induced parameter changes in the semiconductor materials.
Solution Approach 2:
The patent implements feedback mechanisms through the delta sigma modulator architecture, where the quantized output is fed back through a digital-to-analog converter and subtracted from the input signal. This feedback loop continuously corrects for temperature drift and maintains output stability despite changes in internal resistance and heating effects.
2Measurement precision
If semiconductor materials are used in delta sigma modulators, then high conversion accuracy is achieved, but internal heating and resistance changes cause temperature sensitivity
Solution Approach 1:
The patent converts the harmful effect of temperature variations into a beneficial characteristic by using logarithmic transformation. In the logarithmic domain, the temperature-dependent behavior of semiconductor materials becomes a predictable shift that can be compensated for, effectively turning the temperature sensitivity into a manageable parameter rather than a fundamental limitation.
Solution Approach 2:
By changing from linear to logarithmic signal representation, the patent alters how temperature effects manifest in the system. The logarithmic transformation compresses the dynamic range and changes the sensitivity characteristics, making the system's response to temperature variations more uniform and compensatable across the operating range.
3Productivity
If linear input signals are processed through delta sigma modulators, then standard conversion operations are performed, but temperature-induced drift affects output stability
Solution Approach 1:
The patent changes the signal representation parameter from linear to logarithmic domain. This transformation affects how the modulator processes signals, maintaining conversion speed while reducing the impact of temperature drift on output stability. The logarithmic domain processing changes the mathematical relationships in the feedback loop, improving temperature insensitivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures that the output of the delta sigma modulator remains relatively temperature-independent, maintaining high accuracy and stability across varying temperatures, thereby enhancing the dynamic range and reliability of the conversion process.
Implementation Method 1
An input signal received by a ΔΣ modulator is processed by a proportional to absolute temperature (PTAT) conditioner. A reference signal is formed by being subject to a feedback loop of the ΔΣ modulator by passing various elements including another PTAT.
Data Source
AI summary
A delta sigma (ΔΣ or DS) modulator includes at least a first proportional to absolute temperature (PTAT) element that conditions an input signal, and a second PTAT element that conditions a reference signal.