Low-Power Voltage Reference Using Work Function Difference
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Solution Overview
Problem
Traditional reference voltage circuits consume high power due to high quiescent current, making them unsuitable for low voltage applications in portable electronic devices, where power consumption needs to be minimized.
Innovation Solution
A low-power reference voltage generator using a transconductance amplifier with MOS transistors having gate terminals made of different polysilicon materials, such as p+ and n+ polysilicon, to generate a stable reference voltage by amplifying the work function difference, resulting in a quiescent current of 1.5 μA or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If traditional bandgap reference voltage generator is used, then reference voltage can be generated, but power consumption is high due to high quiescent current
Solution Approach 1:
The patent changes the fundamental operating parameters by using MOS transistors instead of bipolar transistors, operating at low voltages (below 0.9V) with quiescent current reduced to 1.5μA or less, while maintaining reference voltage stability through work function difference between polysilicon gate terminals
Solution Approach 2:
The patent substitutes bipolar transistor-based bandgap reference mechanism with MOS transistor-based work function difference mechanism, replacing the traditional mechanical/electrical system with a different physical principle that achieves lower power consumption
2Reliability
If bipolar transistors are used in reference voltage generator, then reference voltage can be generated, but quiescent current reaches very high value of 50-60 μA
Solution Approach 1:
The patent replaces bipolar transistors with MOS transistors, substituting a different device physics mechanism that inherently consumes less current, reducing quiescent current from 50-60μA to 1.5μA or less while maintaining reference voltage generation capability
Solution Approach 2:
The patent changes the device type and operating parameters from bipolar to MOS transistors, enabling operation at ultra-low current levels by exploiting work function differences rather than relying on bipolar transistor VBE characteristics
3Use of energy by stationary object
If low operating voltage below 0.9V is used, then power consumption is reduced, but traditional reference voltage circuits cannot meet the low voltage reference requirement
Solution Approach 1:
The patent changes the reference voltage generation mechanism to work function difference, which is inherently suitable for low voltage operation, enabling the circuit to function correctly at voltages below 0.9V where traditional bandgap references fail
Solution Approach 2:
The patent substitutes the traditional bandgap reference mechanism with a work function difference-based MOS transistor mechanism that is naturally adapted to low voltage operation, expanding the circuit's adaptability to low voltage environments
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 low-power consumption reference voltage generator that maintains a stable output voltage over a wide range of temperatures, suitable for battery-operated devices by utilizing the work function difference between polysilicon gate terminals to reduce power consumption.
Implementation Method 1
The present invention utilizes the work function difference between gate terminals of an input terminal transistor pair, to generate a predetermined reference voltage
Data Source
AI summary
A circuit provides a voltage reference using very low power. It can also be used as a shut regulator for a quiescent current as low as 1.5 μA. It includes a transconductance amplifier, a gain stage, and a power transistor. One embodiment of this invention utilizes a work function difference between p+ gate and n+ gate to generate a predetermined reference voltage. In another embodiment of this invention, the predetermined reference voltage can be pre-adjusted using gate materials with different work functions.