Voltage Reference Error Correction for 1/f Noise and Temperature Drift
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Solution Overview
Problem
Voltage reference circuits in electronic systems are affected by temperature, mechanical stress, and 1/f noise, which hinder high accuracy in analog-to-digital converters, as existing compensation methods are unavailable for continuous-time generators.
Innovation Solution
A method and circuit that generate an adjusted output signal by combining calibrated voltages based on pnp and npn transistors' base-emitter voltages and a voltage proportional to absolute temperature, using digital estimation and error correction to mitigate noise and external variations, with optional low-pass filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chopping and/or auto-zero techniques are used to remove 1/f noise, then 1/f noise is removed, but these methods are unavailable for continuous-time voltage reference generators
Solution Approach 1:
The patent replaces the mechanical/discrete time-domain chopping technique with an electronic/continuous time-domain integration technique. The sigma-delta modulation and digital integration process substitutes the mechanical switching approach, enabling 1/f noise removal in continuous-time voltage reference generators while maintaining the noise cancellation capability.
Solution Approach 2:
The patent changes the operational parameter from discrete time-domain sampling (chopping) to continuous time-domain integration with digital processing. By converting the analog voltage reference through sigma-delta modulation and applying digital integration, the system achieves 1/f noise removal while operating in continuous time, thus adapting the noise cancellation method to the continuous-time architecture.
2Temperature
If temperature coefficient correction using look up tables is applied, then temperature variations are compensated, but the method requires known properties of pnp and npn transistors and discrete time operation
Solution Approach 1:
The patent implements a feedback mechanism where the digital integration process continuously monitors and corrects temperature-induced voltage drifts. The system uses the relationship between PTAT voltage and temperature to dynamically adjust the voltage reference, providing automatic temperature compensation without requiring external look-up tables or discrete time processing corrections.
Solution Approach 2:
The voltage reference generator performs self-compensation for temperature variations through the integrated digital correction process. The system inherently tracks temperature changes via the PTAT voltage and automatically adjusts the output voltage reference to maintain stability, eliminating the need for external temperature sensors or manual calibration tables.
3Object-affected harmful factors
If sigma-delta modulation and digital integration are used, then 1/f noise is reduced and temperature compensation is achieved, but the system complexity increases with ADC, DAC, and digital processing components
Solution Approach 1:
The patent achieves multi-functionality by having the ADC-DAC-digital processing block perform multiple functions simultaneously: 1/f noise reduction through sigma-delta modulation, temperature compensation through digital integration using PTAT voltage, and voltage reference stabilization. This single integrated block replaces what would otherwise require separate noise filtering circuits, temperature sensing circuits, and compensation circuits, thereby reducing overall system complexity despite the sophisticated processing involved.
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 provides an accurate and reliable voltage reference by reducing 1/f noise and compensating for temperature and mechanical stress, achieving up to 30 dB lower noise and improved system performance.
Implementation Method 1
a first calibrated voltage based on a base-emitter voltage of one or more pnp transistors, a second calibrated voltage based on a base-emitter voltage of one or more npn transistors
Implementation Method 2
a voltage that is proportional to absolute temperature
Data Source
AI summary
There is provided systems for and methods of generating of an adjusted output signal. The method may include: providing an unadjusted voltage reference; receiving at least one of a first calibrated voltage based on a base-emitter voltage of one or more pnp transistors, a second calibrated voltage based on a base-emitter voltage of one or more npn transistors, and a voltage that is proportional to absolute temperature; determining a digital estimate of the output signal based on an analog representation of the output signal, and based on the at least one of the first calibrated voltage, the second calibrated voltage, and the voltage that is proportional to absolute temperature; deriving an error in the digital estimate of the output signal based on a difference between the digital estimate of output signal and an ideal digital output signal; and combining the error in the digital estimate of the output signal with the unadjusted voltage reference in order to generate the adjusted output signal.