Reference Voltage Circuit Ultra-Low Power Subthreshold Biasing
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Solution Overview
Problem
Existing reference voltage generating circuits consume high power and are limited to producing a single reference voltage, making them unsuitable for ultra-low power systems like RFID, which require multiple reference voltages for bias and start-up operations.
Innovation Solution
A reference voltage generating circuit comprising a constant current circuit, current mirror circuit, voltage control circuit using substrate transistors driven by PTAT and MOS transistors driven by CTAT voltages, and an output circuit that amplifies and adjusts multiple reference voltages, with feedback mechanisms to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference voltage generating circuit uses transistors and resistance to generate a stable reference voltage, then the reference voltage stability is improved, but the total size of the circuit increases and power consumption increases
Solution Approach 1:
The patent changes the operating parameters of transistors by driving substrate PNP transistors in subthreshold region and MOS transistors in saturation region, achieving ultra-low power consumption while maintaining stable reference voltage generation through parameter optimization rather than traditional resistor-based approaches
Solution Approach 2:
The patent replaces traditional resistor-based voltage generation with a transistor-based system using PTAT and CTAT voltage compensation, eliminating the need for large resistance values and reducing both circuit size and power consumption
2Use of energy by stationary object
If a reference voltage generating circuit uses FET instead of transistor, then power consumption is reduced, but it still consumes 12 μA which is insufficient for ultra-low power systems
Solution Approach 1:
The patent further reduces power consumption from 12 μA to below 200 nA by changing the operating parameters to subthreshold region for PNP transistors and optimizing MOS transistor biasing, making the circuit suitable for ultra-low power RFID systems
Solution Approach 2:
The patent enhances versatility by generating multiple reference voltages (VREF1, VREF2, VREF3) from a single circuit architecture, enabling the circuit to serve multiple functions including bias generation and start-up operations in ultra-low power systems
3Device complexity
If a reference voltage generating circuit generates only one single reference voltage, then the circuit complexity is reduced, but it cannot supply reference voltages required for bias or start-up operations
Solution Approach 1:
The patent implements multi-functionality by designing a single circuit that generates multiple reference voltages (VREF1, VREF2, VREF3) with different characteristics, enabling one circuit to fulfill multiple roles including main reference, bias generation, and start-up functions
Solution Approach 2:
The patent segments the output stage to provide multiple reference voltages with different characteristics by tapping at different points in the voltage generation chain and using separate output buffers, allowing each reference voltage to be optimized for its specific application
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 circuit achieves ultra-low power consumption of below 200 nA, enabling the generation of multiple stable reference voltages independent of supply voltage, temperature, and process changes, suitable for ultra-low power systems such as RFID.
Implementation Method 1
a voltage control circuit part receiving the second constant current and generating a first reference voltage by using substrate transistors driven by a PTAT (Proportional To Absolute Temperature) voltage
Implementation Method 2
MOS transistors driven by a CTAT (Complementary To Absolute Temperature) voltage
Implementation Method 3
an output circuit part amplifying an output voltage from the voltage control circuit part to generate second to fourth reference voltages
Data Source
AI summary
A reference voltage generating circuit with ultra-low power consumption, which includes: a constant current circuit part generating a first constant current from a supply voltage; a current mirror circuit part mirroring the constant current and supplying a second constant current; a voltage control circuit part receiving the second constant current and generating a first reference voltage by using substrate transistors driven by a PTAT (Proportional To Absolute Temperature) voltage and MOS transistors driven by a CTAT (Complementary To Absolute Temperature) voltage; and an output circuit part amplifying an output voltage from the voltage control circuit part to generate second to fourth reference voltages, and feeding back at least one of the second to fourth reference voltages to the voltage control circuit part so that the magnitude of an output voltage is adjusted. The reference voltage generating circuit is able to stably output four reference voltages, independently of changes in supply voltage, process, temperature, and other factors.