Reference Voltage Circuit Using Series MOS Transistors Under External Stress
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Solution Overview
Problem
Existing reference voltage circuits face challenges in maintaining stability and reducing current consumption due to external stress, such as resin shrinkage during the resin sealing process, which affects transistor characteristics.
Innovation Solution
The reference voltage generation device employs a combination of depletion and enhancement type MOS transistors with small channel sizes, connected in series, to suppress the influence of external stress and reduce current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the channel length of transistors is increased to suppress drain current and reduce current consumption, then current consumption is reduced, but the electrical characteristics become more sensitive to external stress such as resin shrinkage, causing reference voltage stability to decrease
Solution Approach 1:
The patent changes the transistor type from enhancement type to depletion type, which fundamentally alters the electrical characteristics. Depletion type transistors have different stress sensitivity characteristics compared to enhancement type transistors, allowing the circuit to achieve low current consumption while maintaining stability under external stress conditions
Solution Approach 2:
The patent applies different transistor types (depletion type vs enhancement type) to different circuits (constant current circuit vs voltage generation circuit) based on their specific functional requirements. The constant current circuit uses depletion type transistors for stress insensitivity, while the voltage generation circuit uses enhancement type transistors for efficient voltage generation
2Use of energy by moving object
If the channel length of transistors is increased to suppress drain current, then current consumption is reduced, but manufacturing precision requirements increase due to greater sensitivity to process variations
Solution Approach 1:
The patent changes the transistor type to depletion type, which has different electrical characteristics that are less sensitive to manufacturing process variations. This parameter change allows the use of shorter channel lengths while maintaining stable performance, thereby reducing current consumption without increasing manufacturing precision requirements
Data Source
AI summary
The present invention provides a reference voltage generation device which includes a constant current circuit outputting a constant current in response to an input voltage; a voltage generation circuit connected in series to the constant current circuit, using the constant current as an input current, and generating an output voltage based on the input current; and a reference voltage output port outputting the output voltage. In the constant current circuit, multiple depletion type MOS transistors are connected in series, the gate widths are the same, and the sum of the gate lengths is the total gate length of the constant current circuit. In the voltage generation circuit, multiple enhancement type MOS transistors are connected in series, the gate widths are the same, and the sum of the gate lengths is the total gate length of the voltage generation circuit.