Bandgap Reference Circuit Switching to Cancel Resistor Drift
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Solution Overview
Problem
Conventional band gap reference voltage generating circuits fail to maintain a reference voltage independent of temperature due to resistance deviations in resistors, which affect the correlation between the reference voltage and temperature.
Innovation Solution
A band gap reference voltage generating circuit is designed with a current generating circuit, a current divider circuit, a connection path switching circuit, and a control circuit to periodically switch connection paths and adjust polarities, effectively reducing the impact of resistance deviations on the reference voltage's temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional band gap reference voltage generating circuit is used, then the reference voltage should be independent of temperature, but resistance deviation causes the reference voltage to be affected by temperature
Solution Approach 1:
The patent employs periodic switching of connection paths through switching circuits, which periodically connect and disconnect different circuit nodes. This periodic action allows the system to average out the effects of resistance deviations over multiple switching cycles, thereby maintaining temperature independence of the reference voltage despite component variations.
Solution Approach 2:
The patent dynamically changes circuit parameters by switching between different connection configurations. By altering which components are connected in which configurations during different time periods, the system can compensate for resistance deviations and maintain the desired temperature-independent reference voltage output.
2Temperature
If resistance values are precisely controlled, then reference voltage temperature independence improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent incorporates feedback mechanisms through operational amplifiers that continuously monitor and adjust circuit parameters. This feedback allows the system to compensate for resistance deviations in real-time, achieving temperature-independent reference voltage without requiring extremely precise resistor manufacturing, thereby easing production requirements.
Solution Approach 2:
The patent introduces switching circuits and operational amplifiers as intermediary elements that mediate between the resistive components and the reference voltage output. These intermediaries process and condition the signals, allowing standard precision resistors to achieve the desired temperature-independent performance through active compensation rather than requiring ultra-precise passive components.
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 solution effectively eliminates the temperature effect on the reference voltage by ensuring that the currents through the current divider circuit match a preset ratio, thereby maintaining a stable reference voltage despite resistance deviations.
Implementation Method 1
The forwardly-conducted base-emitter voltage VBE1 has a negative temperature coefficient, that is, a value of dVBE1/dT is negative; and ΔVBE is a positive temperature coefficient, that is, a value of d(ΔVBE)/dT is positive
Data Source
AI summary
A band gap reference voltage generating circuit includes a reference voltage generating circuit, a current generating circuit, a current divider circuit, and a first connection path switching circuit. The reference voltage generating circuit forms a reference voltage on first and second current input terminals thereof. First and second input terminals of the current generating circuit are connected to the first and second current input terminals, respectively. The current generating circuit generates a first current to bias the reference voltage generating circuit. The current divider circuit includes a current input terminal, a first current output terminal, and a second current output terminal. The first connection path switching circuit switches connection paths between the first input terminal and the second input terminal of the current generating circuit, and the first current input terminal and the second current input terminal of the current divider circuit.