Regulator Circuit Gate Filter Using Low-Voltage MOS Capacitors
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Solution Overview
Problem
Existing regulator circuits require larger circuit areas due to the use of high-voltage MOS capacitors to maintain necessary capacitance values, leading to increased noise and layout issues.
Innovation Solution
Incorporation of a low-voltage MOS capacitor in the low-pass filter circuit, combined with an analog switch to protect the capacitor from excessive voltages, and a phase compensation capacitor for maintaining phase margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a MOS capacitor with increased gate oxide film thickness is used to increase withstand voltage, then the transistor can withstand higher voltages, but the capacitance value per unit area decreases requiring larger circuit area
Solution Approach 1:
The patent segments the capacitor system into two distinct parts: a high-voltage MOS capacitor for noise filtering and a low-voltage capacitor for phase compensation. This segmentation allows each capacitor to be optimized for its specific function, with the high-voltage capacitor handling voltage spikes and the low-voltage capacitor providing precise phase control, thereby reducing the total circuit area while maintaining reliability
Solution Approach 2:
The patent introduces a switching circuit as an intermediary between the high-voltage and low-voltage capacitors. This switching circuit selectively connects the appropriate capacitor based on voltage conditions, allowing the high-voltage capacitor to protect against voltage spikes while the low-voltage capacitor provides efficient phase compensation during normal operation, thus resolving the area-vs-reliability contradiction
2Area of stationary object
If a low-voltage MOS capacitor is used to reduce circuit area, then the capacitance density increases, but the capacitor cannot withstand excessive voltages
Solution Approach 1:
The patent segments the capacitor system into two distinct parts: a high-voltage MOS capacitor for noise filtering and a low-voltage capacitor for phase compensation. This segmentation allows each capacitor to be optimized for its specific function, with the high-voltage capacitor handling voltage spikes and the low-voltage capacitor providing precise phase control, thereby reducing the total circuit area while maintaining reliability
Solution Approach 2:
The patent introduces a switching circuit as an intermediary between the high-voltage and low-voltage capacitors. This switching circuit selectively connects the appropriate capacitor based on voltage conditions, allowing the high-voltage capacitor to protect against voltage spikes while the low-voltage capacitor provides efficient phase compensation during normal operation, thus resolving the area-vs-reliability contradiction
3Area of stationary object
If the gate oxide film thickness is increased to increase capacitance value, then the capacitance per unit area increases, but the withstand voltage decreases
Solution Approach 1:
The patent segments the capacitor system into two distinct parts: a high-voltage MOS capacitor for noise filtering and a low-voltage capacitor for phase compensation. This segmentation allows each capacitor to be optimized for its specific function, with the high-voltage capacitor handling voltage spikes and the low-voltage capacitor providing precise phase control, thereby reducing the total circuit area while maintaining reliability
Solution Approach 2:
The patent introduces a switching circuit as an intermediary between the high-voltage and low-voltage capacitors. This switching circuit selectively connects the appropriate capacitor based on voltage conditions, allowing the high-voltage capacitor to protect against voltage spikes while the low-voltage capacitor provides efficient phase compensation during normal operation, thus resolving the area-vs-reliability contradiction
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
Reduces circuit area while effectively reducing noise and maintaining stability, with improved reliability and reduced power consumption.
Implementation Method 1
a low-pass filter circuit outputting a drive voltage obtained by filtering an output voltage of the operational amplifier
Implementation Method 2
the low-pass filter circuit includes a MOS capacitor provided between the gate of the output transistor and a second power supply node
Data Source
AI summary
A regulator circuit includes an N-type output transistor provided between a first power supply node and an output node of a regulated voltage, an operational amplifier having a first input terminal to which a reference voltage is input and a second input terminal to which a feedback voltage based on the regulated voltage is input, and a low-pass filter circuit outputting a drive voltage obtained by filtering an output voltage of the operational amplifier to a gate of the output transistor. The low-pass filter circuit includes a MOS capacitor provided between the gate of the output transistor and a second power supply node and including a transistor having a withstand voltage lower than that of the output transistor.