Offset Correction Circuit With Opposing Temperature Coefficients
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Solution Overview
Problem
It is challenging to manufacture voltage sources and resistive elements completely independent of temperature, leading to increased costs and accuracy issues in offset voltage correction, particularly in CMOS processes for digital signal processing.
Innovation Solution
An offset correction circuit is designed with a first and second correction voltage generation circuit, where the second correction voltage has a temperature coefficient reverse in polarity to the first, allowing for effective offset voltage correction even with temperature-dependent elements by suppressing the fluctuation of their sum with temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature-independent voltage sources and resistive elements are used for offset correction, then temperature drift is suppressed, but manufacturing cost increases and such components are difficult to manufacture
Solution Approach 1:
The patent converts the harmful temperature dependency of standard CMOS voltage sources and resistive elements into a beneficial feature by designing correction circuits that generate compensation voltages with opposite temperature coefficients. The first correction voltage generation circuit generates a correction voltage with a positive temperature coefficient, while the second generates a correction voltage with a negative temperature coefficient. When combined, these compensation voltages cancel out the temperature drift effects, allowing the use of inexpensive, easily manufacturable temperature-dependent components to achieve temperature-independent offset correction.
2Measurement precision
If temperature-independent components are used for offset correction, then offset voltage accuracy is improved, but component cost increases
Solution Approach 1:
The patent transforms the temperature sensitivity of standard CMOS components into an advantage by generating two correction voltages with opposite temperature coefficients. The first correction voltage generation circuit produces a voltage that increases with temperature, while the second produces a voltage that decreases with temperature. Their sum maintains a stable total correction voltage across temperature variations, achieving high offset voltage accuracy using only standard, low-cost CMOS components.
Solution Approach 2:
The patent changes the temperature coefficient parameter of correction voltages by using different circuit configurations. The first correction voltage generation circuit uses a configuration that produces a positive temperature coefficient, while the second uses a different configuration to produce a negative temperature coefficient. This parameter transformation allows the system to achieve temperature compensation without requiring expensive temperature-independent components.
Data Source
AI summary
A first correction voltage generation circuit provides a first positive or negative correction voltage for correcting an input voltage. A second correction voltage generation circuit provides a second correction voltage identical in polarity to the first correction voltage in accordance with the first correction voltage. The second correction voltage is generated to have a temperature coefficient reverse in polarity to a temperature coefficient of the first correction voltage.