Comparator-Based Power-On Reset Circuit Without Current Mirror Drift
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Solution Overview
Problem
Conventional power-on reset circuits face challenges in accurately indicating when the input voltage reaches a specific level for backend circuits to start working due to high power consumption and large layout area requirements, and process variations in current mirror structures can lead to inaccurate voltage detection.
Innovation Solution
A power-on reset circuit design utilizing a first and second resistor, transistors, and a comparator to generate a power-on reset signal, where the resistors and transistors are matched to ensure accurate voltage detection with reduced power consumption and layout area, eliminating the need for a shut-down switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage dividing resistors are utilized for dividing the input voltage, then accurate voltage detection is achieved, but large layout area and high power consumption occur
Solution Approach 1:
The patent changes the operating parameters by using transistors in saturation region to generate voltage drops (VGS3, VGS4) that replace traditional resistor voltage division. This allows accurate voltage detection through transistor gate-source voltage differences rather than resistive division, reducing layout area while maintaining detection precision.
2Measurement precision
If voltage dividing resistors are utilized for dividing the input voltage, then accurate voltage detection is achieved, but high power consumption occurs
Solution Approach 1:
The patent changes the energy consumption parameter by replacing resistive voltage division with transistor-based voltage generation. The transistors MP3 and MP4 operate in saturation region to generate stable voltage drops with minimal current consumption, achieving accurate voltage detection without the high power consumption associated with large resistance values.
3Loss of energy
If a shut-down switch is utilized to cut off all current when power is turned off, then power consumption is reduced, but on-resistance forms causing voltage difference
Solution Approach 1:
The patent extracts and eliminates the shut-down switch component from the circuit. Instead of using a switch to cut off current, the circuit design allows transistors to naturally operate in saturation region, generating the required voltage drops without needing to completely cut off current, thereby avoiding the on-resistance problem while maintaining low power consumption.
4Area of stationary object
If current mirrors are utilized to control the power-on reset signal, then layout area is reduced, but process variation causes inaccurate voltage detection
Solution Approach 1:
The patent introduces an intermediary approach by using the gate-source voltage differences of transistors MP3 and MP4 as the mediating mechanism. Instead of directly relying on current mirror ratios which are sensitive to process variation, the circuit uses voltage drops across transistor gates as intermediaries to achieve accurate voltage detection that is less sensitive to process 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 solution accurately performs power-on reset with low power consumption and smaller layout area, ensuring accurate detection of the input voltage reaching a specific level for backend circuits to start working, while avoiding process variations and on-resistance issues.
Implementation Method 1
a comparator, comprising a first input terminal and a second input terminal, wherein the first input terminal is coupled between the first terminal of the second resistor and the second terminal of the first resistor for receiving a comparison voltage, the second input terminal is utilized for receiving the reference voltage, and the comparator is utilized for generating a power-on reset signal according to the comparison voltage and the reference voltage
Data Source
AI summary
A power-on reset circuit is disclosed. The power-on reset circuit includes a first resistor; a first transistor, including a first terminal coupled to a second terminal of the first resistor, and a control terminal for receiving a reference voltage; a second resistor, including a first terminal coupled to a second terminal of the first transistor; a second transistor, including a first terminal coupled to a second terminal of the first resistor, and a control terminal coupled to a second terminal of the second transistor and utilized for receiving an input voltage; and a comparator, including a first input terminal for receiving a comparison voltage, and a second input terminal for receiving the reference voltage, for generating a power-on reset signal according to the comparison voltage and the reference voltage.