Bandgap Reference Knee-Point Compensation for Extreme Temperature Drift
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Solution Overview
Problem
Bandgap reference circuits experience significant temperature drift due to manufacturing process variations and component mismatch, especially at extreme temperatures, limiting the precision of the reference voltage signal in applications like ADCs and DACs.
Innovation Solution
A piecewise compensation circuit with a knee point temperature adjustment mechanism, utilizing a current DAC to provide analog piecewise compensation current signals, and including first and second trim DACs for linear and nonlinear compensation, effectively mitigates higher order temperature drift effects by adjusting the knee point temperature based on a multi-bit code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If first and second order trimming for curvature correction and two-temperature trim are used, then temperature drift is reduced to some extent, but higher order temperature drift effects remain significant at extreme temperatures
Solution Approach 1:
The temperature compensation is divided into multiple segments: first order trimming, second order curvature correction, and third order higher order drift compensation. Each segment addresses specific temperature ranges and drift characteristics, with the third order compensation specifically targeting extreme temperature performance.
Solution Approach 2:
Different trimming mechanisms are applied to different temperature regions. The first trim DAC handles lower temperature ranges, while the second trim DAC addresses higher temperature ranges, allowing optimized compensation for each region's specific drift characteristics.
2Measurement precision
If higher order temperature drift effects are compensated, then precision is improved, but device complexity increases due to additional trimming circuits
Solution Approach 1:
Multiple trimming functions are merged into a unified piecewise compensation architecture. The first and second trim DACs are integrated with the bandgap reference circuit, sharing common biasing and control structures, which reduces overall complexity compared to separate compensation circuits.
Solution Approach 2:
The compensation circuit uses dynamic, temperature-dependent control through the trim DACs that automatically adjust their output based on the temperature range. This dynamic adaptation allows a single circuit structure to handle multiple temperature regions without requiring separate static compensation paths.
3Ease of manufacture
If manufacturing process variations and component mismatch are present, then production cost is reduced, but temperature drift performance deteriorates
Solution Approach 1:
The circuit uses programmable trim DACs that allow post-fabrication adjustment of compensation parameters. This enables the circuit to adapt to process variations and component mismatches by digitally tuning the compensation magnitude, maintaining performance despite manufacturing tolerances.
Data Source
AI summary
An electronic device includes a bandgap reference circuit having an output, and a bias input; a piecewise compensation circuit having an output coupled to the bias input, and an input; and a piecewise compensation current generator having an output coupled to the input of the piecewise compensation circuit, and a knee point temperature adjustment circuit coupled to the output of the piecewise compensation current generator.