Reference Voltage Generator Using N- and P-Type FETs
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Solution Overview
Problem
Existing reference voltage generators require high operating voltages and are sensitive to fabrication process, supply voltage, and ambient temperature variations, failing to meet modern low voltage and low power consumption requirements.
Innovation Solution
A novel reference voltage generator using a pair of field effect transistors with n-type and p-type heavily doped gate structures, where the transistors are configured to produce a reference voltage based on the difference in their threshold voltages, allowing for operation at low voltages and reduced sensitivity to process and temperature variations by adjusting their aspect ratios and incorporating additional transistors for stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reference voltage generators using heavily doped gate structures are used, then a stable reference voltage can be generated, but high operating voltage is required
Solution Approach 1:
The patent changes the doping type parameter of the gate structures from conventional single-type to dual-type (n-type and p-type), which fundamentally alters the threshold voltage characteristics and enables operation at lower voltages while maintaining reference stability
Solution Approach 2:
The invention uses composite transistor structures combining n-type and p-type heavily doped gate transistors in a differential configuration, creating a composite reference voltage generation system that overcomes the high voltage requirement of conventional single-type structures
2Reliability
If conventional reference voltage generators are used, then reference voltage can be generated, but the output is sensitive to fabrication process variations
Solution Approach 1:
The patent introduces asymmetry by using opposite doping types (n-type and p-type) for the two transistors in the differential pair, creating inherently different threshold voltage characteristics that are less susceptible to common-mode fabrication variations
Solution Approach 2:
The differential configuration inherently provides feedback mechanisms where variations in one transistor are compensated by the other, reducing the overall sensitivity to fabrication process variations
3Reliability
If conventional reference voltage generators are used, then reference voltage can be generated, but the output is sensitive to supply voltage variations
Solution Approach 1:
The differential configuration with n-type and p-type transistors creates equipotential conditions that cancel out supply voltage variations, making the reference voltage output independent of supply voltage fluctuations
4Reliability
If conventional reference voltage generators are used, then reference voltage can be generated, but the output is sensitive to ambient temperature variations
Solution Approach 1:
The patent uses the opposite doping types as counterbalancing elements where the temperature coefficient of one transistor compensates for the other, creating a temperature-independent reference voltage output
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 enables a stable reference voltage generation at low voltages, with minimal variations across different conditions, achieving a constant output voltage of approximately 0.5 volts and reduced temperature coefficient, thus addressing the limitations of existing technologies.
Implementation Method 1
field effect transistors (FETs) with heavily doped gate structures, where a reference voltage is obtained as a difference in threshold voltage between a pair of FET devices
Data Source
AI summary
A reference voltage generator includes a first field effect transistor with n-type heavily doped gate structure and a second field effect transistor with p-type heavily doped gate structure. The first transistor is configured to have a gate and a substrate gate connected to ground, one terminal connected to a voltage supply, and another terminal connected to an output node. The second transistor is configured to have a gate and one terminal connected to the output node, and a substrate gate and another terminal connected to ground. The output node outputs a given reference voltage when voltage is supplied from the voltage supply. A voltage regulator that generates a constant voltage based on a given reference voltage incorporates the reference voltage generator.