Constant Voltage Circuit Back Gate Leakage Control
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Solution Overview
Problem
Conventional constant voltage circuits experience uncontrollable output voltage due to leakage current, especially at high temperatures, leading to rapid voltage fluctuations and potential malfunctions or element breakdowns.
Innovation Solution
A constant voltage circuit that includes an error amplifier circuit, an output transistor, a detection circuit for leakage current, and a first voltage generation circuit that generates a voltage proportional to the leakage current, which is applied to the back gate of the output transistor to control and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output transistor operates in off direction to reduce leakage current, then the output voltage should remain stable, but the leakage current increases at high temperature causing output voltage to rise uncontrollably
Solution Approach 1:
The patent changes the threshold voltage parameter of the output transistor by applying a back gate voltage. When temperature increases and leakage current rises, the back gate voltage is adjusted to increase the threshold voltage, thereby reducing the leakage current and maintaining output voltage stability.
Solution Approach 2:
The patent implements a feedback mechanism where the output voltage is monitored and compared with a reference voltage. When leakage current causes the output voltage to deviate, the error amplifier adjusts the back gate voltage to counteract the leakage effect, creating a closed-loop control system that maintains voltage stability.
2Object-generated harmful factors
If a high voltage is supplied to the back gate to reduce leakage current, then the leakage current decreases, but the output voltage fluctuates rapidly due to switching noise
Solution Approach 1:
The patent dynamically adjusts the back gate voltage based on the detected leakage current level rather than applying a fixed high voltage. The voltage generation circuit modifies the back gate voltage in proportion to the leakage current, creating a dynamic response that reduces leakage while minimizing output voltage fluctuations.
Solution Approach 2:
Instead of switching between fixed voltage levels, the patent continuously adjusts the back gate voltage parameter in proportion to the leakage current magnitude. This analog control approach avoids the abrupt transitions that cause switching noise while still effectively suppressing leakage current.
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
This solution effectively reduces leakage current and suppresses output voltage fluctuations, preventing malfunctions and element breakdowns while maintaining a stable output voltage.
Implementation Method 1
a first voltage generation circuit configured to generate a voltage proportional to the leakage current detected by the detection circuit. The first voltage generation circuit raises a voltage to be generated according to an increase in the leakage current, and an output of the first voltage generation circuit is coupled to a back gate of the output transistor
Data Source
AI summary
In a constant voltage circuit including: an error amplifier circuit amplifying a difference voltage between an output voltage and a reference voltage; and an output transistor controlling the output voltage based on an output of the error amplifier circuit, a voltage proportional to a leakage current detected by a monitoring transistor is generated by an oscillation circuit and a charge pump circuit and is supplied to a back gate of the output transistor.