Bandgap Reference Correction Current Circuit for Nonlinear Temperature Drift
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Solution Overview
Problem
Conventional bandgap reference voltage circuits face challenges in accurately correcting non-linear temperature characteristics due to the difficulty in estimating and adjusting the non-linearity of the temperature characteristic in actual manufactured circuits.
Innovation Solution
A correction current output circuit comprising a bandgap reference voltage circuit, multiple-stage voltage dividing circuits, and differential pairs with unique gate potentials, allowing for adjustable correction currents to be generated and applied to correct the temperature characteristic of the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two differential pairs are used to correct temperature characteristic, then temperature correction function is provided, but the non-linear temperature characteristic cannot be accurately corrected due to difficulty in estimating non-linearity
Solution Approach 1:
The correction current is segmented into multiple independent currents (first correction current from first differential pair, second correction current from second differential pair). Each differential pair can be independently controlled through separate voltage dividing circuits, allowing granular adjustment of correction amounts for different temperature ranges, thereby addressing the non-linear temperature characteristic more accurately.
Solution Approach 2:
The patent introduces dynamic adjustability by connecting voltage dividing circuits to the gates of transistors in each differential pair. This allows the correction current magnitude to be dynamically adjusted based on temperature conditions, transforming the static correction approach into a dynamic one that can adapt to non-linear temperature variations.
2Device complexity
If same level voltage with positive temperature characteristic is applied to one gate of transistors, then circuit structure is simplified, but the degree of freedom in correcting non-linear temperature characteristic is insufficient
Solution Approach 1:
Instead of applying a single voltage to one gate, the patent segments the correction function into two independent differential pairs, each with its own voltage dividing circuit. This segmentation provides additional degrees of freedom for correction while maintaining reasonable circuit complexity through modular design.
Solution Approach 2:
Each differential pair is assigned a specific function in the temperature correction process, with different voltage dividing circuits providing locally optimized correction currents. This local quality approach allows different parts of the correction system to be optimized for different temperature ranges, increasing overall correction freedom.
Data Source
AI summary
A correction current output circuit comprises a first voltage dividing circuit for generating a voltage in which an output voltage from a bandgap reference voltage circuit is divided in multiple stages, first and second correction circuits connected between a power supply and a ground, and a second voltage dividing circuit for dividing the above voltage in multiple stages in a path in which a positive temperature characteristic voltage is generated with the band gap reference voltage circuit. Current output terminals of a the second transistor of the first correction circuit and a first transistor of the second correction circuit are connected to a common connection point, and a current for correcting the temperature characteristic of a reference voltage generation circuit is output from the common connection point.