Bandgap Correction Circuit for Current Gain Mismatch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bandgap circuits in electronic devices, particularly those implemented in FinFet technology, face issues with delivering a temperature-stable DC voltage due to current gain differences between bipolar transistors, leading to errors in the value of the generated voltage.
Innovation Solution
A correction circuit is introduced, which includes a first and second bipolar transistor with a correction current generated as the difference between their base currents, injected into the emitter of one transistor to equalize emitter currents and correct the voltage error, utilizing MOS transistors and resistors to maintain temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a bandgap circuit uses bipolar transistors with different dimensions to generate temperature-stable voltage, then temperature stability is improved, but current gain differences between transistors cause voltage value errors
Solution Approach 1:
The patent implements a feedback mechanism by generating a correction current based on the difference between base currents of the two bipolar transistors. This correction current is then fed back to adjust the emitter current, compensating for the voltage error caused by current gain differences. The feedback loop continuously monitors and corrects the voltage output to maintain both temperature stability and accuracy.
Solution Approach 2:
The patent dynamically adjusts the emitter current parameter by adding a correction current component. This parameter change compensates for the effects of current gain variations between transistors while preserving the temperature-stable voltage characteristic. The correction current modifies the effective emitter current to achieve accurate voltage output.
2Ease of manufacture
If bipolar transistors operate with different base currents due to current gain differences, then the circuit functions with standard components, but emitter current inequality causes voltage errors
Solution Approach 1:
The patent applies local quality by treating the two bipolar transistors differently through selective current adjustment. While both transistors have different base currents due to manufacturing variations, the correction circuit specifically targets one transistor's emitter current to compensate for the difference. This localized adjustment maintains voltage accuracy without requiring complete symmetry in transistor characteristics.
3Stability of the object's composition
If the bandgap circuit is designed for temperature stability using base-emitter voltage differences, then temperature-independent voltage is achieved, but current gain variations introduce systematic errors
Solution Approach 1:
The correction current acts as an intermediary element between the two bipolar transistors. It mediates the effect of current gain differences by providing an compensating current that balances the emitter currents. This intermediary correction mechanism preserves the temperature stability achieved through base-emitter voltage differences while eliminating systematic errors from transistor mismatches.
Data Source
AI summary
The present description concerns a correction circuit for a bandgap circuit comprising a first bipolar transistor and a second bipolar transistor, the bandgap circuit being configured to deliver a temperature-stable DC voltage based on the first and second bipolar transistors, the correction circuit being configured to generate a correction current equal to a difference in the base currents of said first and second transistors, and inject the correction current on the emitter of one of said first and second bipolar transistors to correct an error on the temperature-stable voltage resulting from a current gain difference between said first and second bipolar transistors.