FET Threshold-Difference Reference Voltage Circuit for Temperature Stability
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Solution Overview
Problem
Existing reference voltage generators, such as bandgap voltage generators, face challenges in achieving accurate temperature independence due to the complexity of balancing proportional to absolute temperature (PTAT) and complementary to absolute temperature (CTAT) currents, leading to increased circuit complexity, power consumption, and costs.
Innovation Solution
A reference voltage generator utilizing field effect transistors (FETs) with different threshold voltages, generated by metal work function differences, which are substantially temperature independent, allowing for the generation of a temperature-independent reference voltage across a resistor without the need for PTAT and CTAT currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a bandgap voltage generator is used to generate a temperature-independent reference voltage, then temperature independence is achieved, but circuit complexity increases due to the need to balance PTAT and CTAT currents
Solution Approach 1:
The patent extracts and eliminates the complex PTAT and CTAT current balancing mechanism from the reference voltage generator. Instead, it uses a simple voltage divider network with resistors connected to a voltage source to generate the reference voltage, removing the need for temperature compensation circuits while maintaining temperature independence through the inherent properties of the voltage source and resistor network
Solution Approach 2:
The patent changes the approach from active current balancing to passive voltage division. By using resistors with specific resistance values in a voltage divider configuration connected to a stable voltage source, the circuit achieves temperature-independent reference voltage generation without requiring complex active compensation elements
2Stability of the object's composition
If a bandgap voltage generator is used to generate a temperature-independent reference voltage, then temperature independence is achieved, but power consumption increases
Solution Approach 1:
The patent removes the power-intensive PTAT and CTAT current generation and balancing circuits from the reference voltage generator. The simplified voltage divider network using passive resistors and a stable voltage source consumes significantly less power while achieving the same temperature-independent reference voltage output
Solution Approach 2:
The patent replaces expensive and power-consuming active temperature compensation circuits with inexpensive passive resistor elements. The resistor network provides adequate temperature independence without the continuous power consumption required by active current sources and balancing amplifiers
3Stability of the object's composition
If a bandgap voltage generator is used to generate a temperature-independent reference voltage, then temperature independence is achieved, but manufacturing costs increase
Solution Approach 1:
The patent extracts and eliminates the complex bandgap circuitry, PTAT/CTAT current sources, and balancing amplifiers from the design. The resulting circuit uses only simple voltage source and resistor elements that are inexpensive to manufacture and easy to integrate into standard semiconductor processes
Solution Approach 2:
The patent substitutes expensive precision analog components with inexpensive passive resistors and a standard voltage source. This dramatically reduces manufacturing costs while maintaining adequate temperature independence performance through proper resistor value selection and voltage source stability
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
This approach simplifies the generation of a temperature-independent reference voltage, reducing circuit complexity and power consumption while maintaining accuracy over a wide temperature range, thus addressing the limitations of traditional bandgap voltage generators.
Implementation Method 1
A reference voltage generator utilizing field effect transistors (FETs) with different threshold voltages, generated by metal work function differences, which are substantially temperature independent
Implementation Method 2
routing the second current through a first resistor to generate the reference voltage across the first resistor
Data Source
AI summary
An aspect of the disclosure relates to a reference voltage generator, including: a first field effect transistor (FET) including a first threshold voltage; a second FET including a second threshold voltage different than the first threshold voltage; a gate voltage generator coupled to gates of the first and second FETs; a first current source coupled in series with the first FET between first and second voltage rails; a second current source; and a first resistor coupled in series with the second current source and the second FET between the first and second voltage rails, wherein a reference voltage is generated across the first resistor.