Voltage Reference Circuit Topology for High PSRR and Low Noise
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Solution Overview
Problem
Conventional voltage reference circuits often consume significant power and circuit area while providing limited power supply rejection ratio (PSRR) and are sensitive to temperature variations and device mismatches.
Innovation Solution
A voltage reference system utilizing a specific configuration of transistors and resistive devices, governed by α-power-law relationships, with carefully selected size ratios and transconductance properties to achieve high PSRR and low noise, maintaining stability across varying power supply voltages and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage reference circuits are used, then power supply rejection ratio (PSRR) is provided, but power consumption and circuit area are significant
Solution Approach 1:
The patent changes the operational parameters of the transistors by operating them in the sub-threshold region rather than strong inversion, and by carefully selecting the size ratios (M and N) to satisfy the α-power-law relationship. This parameter optimization enables high PSRR with reduced power consumption and circuit area compared to conventional designs
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the circuit to maintain optimal performance across varying conditions through the α-power-law relationship. The size ratios M and N are selected to compensate for process variations and temperature changes, enabling the circuit to dynamically adapt and maintain high PSRR without increasing power consumption
2Reliability
If conventional voltage reference circuits are used, then reference voltage is provided, but temperature stability is poor across wide temperature range
Solution Approach 1:
The patent operates transistors in the sub-threshold region where the α-power-law relationship provides better temperature stability. By selecting size ratios M and N that satisfy the α-power-law relationship, the circuit achieves improved temperature stability across wide temperature ranges compared to conventional strong-inversion designs
Solution Approach 2:
The circuit employs implicit feedback through the α-power-law relationship where the transistor size ratios M and N are selected to automatically compensate for temperature variations. This feedback mechanism maintains stable reference voltage output across wide temperature ranges without requiring additional temperature compensation circuitry
3Reliability
If conventional voltage reference circuits are used, then reference voltage is provided, but sensitivity to device mismatches is high
Solution Approach 1:
The patent changes the operating region to sub-threshold and selects transistor size ratios M and N to satisfy the α-power-law relationship. This parameter selection makes the reference voltage less sensitive to device mismatches and process variations, improving robustness against manufacturing tolerances
Solution Approach 2:
The circuit provides dynamic compensation for device mismatches through the α-power-law relationship. The size ratios M and N are selected to automatically adjust for process variations, making the reference voltage output robust against device mismatch effects without requiring precision matching
4Reliability
If conventional voltage reference circuits are used, then power supply rejection is provided, but circuit area is significant
Solution Approach 1:
The patent optimizes transistor size ratios M and N to satisfy the α-power-law relationship, which enables high PSRR with minimized circuit area. By operating in sub-threshold region and carefully selecting parameters, the circuit achieves area efficiency without sacrificing power supply rejection performance
Data Source
AI summary
A voltage reference circuit that can operate in a large supply voltage range with high PSRR, that dissipates low-power for a given output noise, and that has a low temperature-coefficient (TC) across a wide-temperature range. The voltage reference circuit does not require any calibration for low TC and high PSRR, occupies a relatively small circuit area, may be used without additional supply filtering in noisy or high-ripple supply environments, and is more robust against device mismatch effects particularly compared to designs based on sub-threshold operations. The voltage reference circuit is a special form of constant transconductance circuit that uses current mirror ratios that are chosen to achieve high PSSR and low noise properties. The device saturation voltage may be chosen so that flat temperature characteristics may be achieved.