Voltage Detection Circuit Using MOS Transistor Channel Length Modulation
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Solution Overview
Problem
Existing voltage detection circuits face challenges in reducing operating current while minimizing chip area and mitigating the influence of manufacturing variations, particularly due to independent manufacturing processes affecting resistor and transistor variations.
Innovation Solution
A voltage detection circuit is designed with a detection circuit comprising MOS transistor units and a current voltage conversion unit, where the voltage characteristics of the currents are crossed at a predetermined voltage, allowing for low operating current consumption without increasing chip area and minimizing the impact of manufacturing variations by utilizing MOS transistors with varying gate lengths and widths to modulate channel length effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a large resistance value (few MΩ) is generated by diffusion resistance or gate POLY resistance to lower operating current, then current consumption is reduced, but chip area increases due to low sheet resistance value
Solution Approach 1:
The patent changes the manufacturing process parameter from diffusion resistance or gate POLY resistance to well resistance, which has a higher sheet resistance value. This parameter change allows achieving the same resistance value (few MΩ) with a smaller physical area, thus reducing chip area while maintaining low current consumption
2Adaptability or versatility
If resistor R1 and depletion type NMOS transistor R2 are manufactured independently in separate manufacturing processes, then design flexibility is improved, but manufacturing variations increase causing large variation in detection voltage
Solution Approach 1:
The patent merges the resistor and depletion type NMOS transistor into the same manufacturing process (both manufactured as CMOS transistors in the same process), eliminating the independence of manufacturing processes. This combination ensures that both components experience the same manufacturing variations, thereby reducing the variation in detection voltage while maintaining design flexibility
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 circuit effectively detects power supply voltage with reduced current consumption and minimized chip area, while maintaining stability against manufacturing variations by leveraging the channel length modulation effects of MOS transistors, ensuring accurate detection voltage without significant threshold voltage influence.
Implementation Method 1
utilizing MOS transistors with varying gate lengths and widths to modulate channel length effects
Implementation Method 2
a voltage characteristic of the first current and a voltage characteristic of the second current are configured to be crossed with each other at a predetermined voltage
Data Source
AI summary
To provide a voltage detection circuit in which the influence on a detection voltage by semiconductor manufacturing variations is small and which is small in current consumption. A voltage detection circuit is provided which detects a voltage, based on an output signal of a detection circuit and outputs a detection signal. The detection circuit includes a first MOS transistor unit which allows a first current to flow, a second MOS transistor unit which allows a second current to flow, and a current voltage conversion unit which converts each of the first current and the second current into a voltage and outputs the same as the detection signal. A voltage characteristic of the first current and a voltage characteristic of the second current are configured so as to be crossed with each other at a predetermined voltage.