Bandgap Reference Circuit Using PTAT and Dual CTAT Compensation
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Solution Overview
Problem
Voltage reference circuits introduce variations in reference voltage due to temperature, supply voltage, and process variations, affecting the performance of circuits that rely on them.
Innovation Solution
A bandgap reference circuit is used, which includes PTAT and CTAT voltage generator circuits with opposite temperature dependencies, and multiple weakly-correlated CTAT voltage generator circuits to reduce variations, generating a reference voltage with reduced temperature and process dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage reference circuit is used to provide a stable reference voltage, then the reference voltage can be used for comparison and control in power converters and ADCs, but the reference voltage exhibits variations due to temperature, supply voltage, and process variations
Solution Approach 1:
The patent applies parameter changes by utilizing voltage sources with opposite temperature coefficients (PTAT and CTAT) and combining them in specific ratios to achieve a reference voltage with minimized temperature dependence. The bandgap circuit generates a PTAT voltage that increases with temperature, while the semiconductor junction devices generate CTAT voltages that decrease with temperature. By summing these voltages with appropriate weighting, the temperature variations are compensated, achieving stable reference voltage across temperature ranges.
Solution Approach 2:
The patent employs a composite approach by combining multiple voltage generation mechanisms (PTAT voltage source, CTAT voltage sources from semiconductor junctions) into a unified bandgap reference circuit. This composite structure leverages the complementary temperature characteristics of different voltage sources to create a reference voltage that is substantially independent of temperature and process variations, achieving high reliability.
2Reliability
If multiple semiconductor junction devices are used to generate CTAT voltages, then the temperature dependence can be reduced through combination, but the circuit complexity increases
Solution Approach 1:
The patent merges multiple CTAT voltage sources from different semiconductor junction devices with a PTAT voltage source into a single bandgap reference circuit. By combining these voltage sources with opposite temperature coefficients, the circuit achieves temperature compensation. The multiple junction devices are connected in a configuration where their CTAT voltages are summed together, and this sum is combined with the PTAT voltage to produce a reference voltage that is substantially independent of temperature variations.
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 bandgap reference circuit effectively minimizes the variation of the reference voltage with temperature and process variations, maintaining stability across different temperatures and integrated circuits, with standard deviations between 0.3%-0.6% of the mean reference voltage.
Implementation Method 1
The first semiconductor junction device is configured to generate a second voltage that decreases with the temperature
Implementation Method 2
The second semiconductor junction device is configured to generate a third voltage that decreases with the temperature
Data Source
AI summary
In one example, an apparatus comprises a voltage reference circuit. The voltage reference circuit has a voltage reference terminal and includes a first circuit, a first semiconductor junction device, and a second semiconductor junction device coupled between the voltage reference terminal and a ground terminal. The first circuit is configured to generate a first voltage that increases with a temperature. The first semiconductor junction device is configured to generate a second voltage that decreases with the temperature. The second semiconductor junction device is configured to generate a third voltage that decreases with the temperature. The voltage reference circuit is configured to generate a fourth voltage between the voltage reference terminal and the ground terminal based on a sum of the first voltage and a combination of the second and third voltages.