Reference Voltage Circuit Using Depletion MOSFET Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing reference voltage circuits exhibit temperature-dependent variations in generated voltage, leading to unreliable constant voltage supply, particularly in low current consumption devices like wearable electronics, due to mismatched temperature coefficients of depletion and enhancement mode MOSFETs, necessitating additional complex circuitry for compensation which increases current consumption.
Innovation Solution
A reference voltage circuit incorporating an additional depletion type MOSFET and resistors is configured to provide current compensation, with the resistance ratio of the resistors adjusted to decrease reference voltage with increasing temperature, utilizing a direct power source and additional current with a positive temperature coefficient to minimize temperature coefficient of the reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional complex circuitry is introduced to compensate for temperature variations, then the temperature coefficient of the reference voltage is reduced, but the current consumption of the reference voltage generating circuit increases
Solution Approach 1:
The patent changes the physical parameters of existing components (depletion mode MOSFET and enhancement mode MOSFET) by introducing a second depletion mode MOSFET with specific characteristics. This additional component provides temperature compensation through its unique electrical parameters, reducing the temperature coefficient of the reference voltage without requiring complex additional circuitry.
Solution Approach 2:
The second depletion mode MOSFET acts as an intermediary element that mediates between the temperature variations and the reference voltage output. By positioning this component in parallel with the first depletion mode MOSFET and configuring its gate connection, it provides a compensating current that offsets temperature-induced voltage drift, achieving stability with minimal additional circuitry.
2Reliability
If the temperature coefficient of the reference voltage is reduced to below 0.5%-0.75% of Vref, then the reliability and constancy of the reference voltage is improved, but the circuit complexity increases
Solution Approach 1:
The patent achieves the target temperature coefficient specification by carefully selecting and configuring the second depletion mode MOSFET with specific electrical parameters. By adjusting the dimensions (width and length) and threshold voltage characteristics of this additional MOSFET, the circuit achieves Δvref_t < 0.5%-0.75% of Vref while maintaining a relatively simple structure.
Solution Approach 2:
The second depletion mode MOSFET serves as a simple intermediary component that provides temperature compensation functionality. Its parallel configuration with the first depletion mode MOSFET and specific gate connection to the source of the enhancement mode MOSFET creates a compact circuit structure that achieves high reliability without significant complexity increase.
3Reliability
If additional depletion mode MOSFET and resistor are used for compensation, then the temperature coefficient is reduced, but the current consumption increases slightly
Solution Approach 1:
The patent optimizes the parameters of the additional depletion mode MOSFET (second MOSFET) and resistor to minimize their impact on current consumption. By carefully selecting the threshold voltage, channel width, and length of the second MOSFET, and choosing an appropriate resistance value, the temperature compensation is achieved with minimal additional current draw, making the solution suitable for low-power applications.
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 proposed circuit achieves a reduced temperature coefficient for the reference voltage, simplifies the design by using only an additional depletion mode MOSFET and resistor, and minimizes current consumption while effectively compensating for temperature variations, ensuring a more reliable and constant reference voltage.
Implementation Method 1
a second depletion type MOSFET having a source electrode, a drain electrode, and a gate electrode, and wherein the drain electrode of the second depletion type MOSFET is connected between the supply potential and the drain electrode of the first depletion type MOSFET, and the source electrode of the second depletion type MOSFET is connected between the source electrode of the first depletion type MOSFET and the drain electrode of the first enhancement type MOSFET
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
A reference voltage generating circuit comprising a first depletion type metal-oxide semiconductor field-effect transistor (MOSFET), a first enhancement type MOSFET, a reference voltage output connected between the first depletion type MOSFET and the first enhancement type MOSFET, and a second depletion type MOSFET.