Bandgap Reference Circuit Using PTAT-CTAT Nonlinear Compensation
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining a stable reference voltage across varying temperatures, leading to potential malfunctions and reduced reliability.
Innovation Solution
A bandgap reference circuit is designed with a reference voltage generating circuit and a compensation circuit, utilizing PTAT and CTAT voltages and currents to generate a stable reference voltage, with non-linear compensation circuits to adjust for temperature changes, ensuring the output voltage remains constant across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional reference voltage circuit is used, then the circuit is simple, but the reference voltage varies with temperature leading to malfunction
Solution Approach 1:
The reference voltage generating circuit is divided into multiple functional blocks: a first circuit generating PTAT voltage, a second circuit generating CTAT voltage, and a compensation circuit generating compensation voltage. Each block performs a specific function in temperature compensation, allowing the system to achieve high reliability through modular temperature compensation while managing complexity through functional segmentation.
Solution Approach 2:
The compensation circuit acts as an intermediary between the PTAT/CTAT voltage generators and the final reference voltage output. It generates a compensation voltage based on temperature characteristics and combines it with the PTAT and CTAT voltages to produce a stable reference voltage, mediating the temperature effects to achieve reliability without excessive complexity.
2Reliability
If temperature compensation is added to stabilize reference voltage, then reference voltage stability improves, but circuit complexity increases
Solution Approach 1:
The circuit utilizes parameter changes in voltage characteristics with temperature. The PTAT voltage increases linearly with temperature, the CTAT voltage decreases with temperature, and the compensation voltage adjusts non-linearly with temperature. By combining these voltage parameters with opposite temperature coefficients, the circuit achieves temperature-independent reference voltage output, improving stability while using inherent physical parameter variations rather than complex active compensation mechanisms.
3Measurement precision
If linear temperature compensation is used, then partial stability is achieved, but non-linear temperature variations remain
Solution Approach 1:
The temperature compensation mechanism uses a composite approach combining multiple voltage sources with different temperature characteristics: PTAT voltage (proportional to absolute temperature), CTAT voltage (complementary to absolute temperature), and compensation voltage (non-linear temperature dependence). This composite voltage combination allows the circuit to compensate for both linear and non-linear temperature variations, achieving high measurement precision and reliability across the entire temperature range.
Data Source
AI summary
A bandgap reference circuit generates a PTAT voltage and a CTAT voltage having a different temperature characteristic from the PTAT voltage and generates a reference voltage based on the PTAT voltage, the CTAT voltage, and a compensation voltage. The bandgap reference circuit generates a CTAT current having a different temperature characteristic from the PTAT voltage based on the CTAT voltage and determines the compensation voltage based on the CTAT current.