Integrator Offset Evaluation Circuit for Low-Noise Charge Reduction
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Solution Overview
Problem
Amplifiers in electronic integrators often suffer from offset voltage issues, which introduce errors and noise, particularly in applications like photodiode amplifiers, where traditional offset cancellation methods are either impractical due to size constraints or introduce additional noise and crosstalk.
Innovation Solution
The integration circuit includes an amplifier, an offset evaluation circuit, an integration capacitor, and a collected charge reduction circuitry, where the offset evaluation circuit charges an offset capacitor with the amplifier's offset voltage, and the collected charge reduction circuitry collects and reduces the charge resulting from disconnecting the offset evaluation circuit, thereby minimizing noise and error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional offset cancellation solutions use large capacitors, then offset voltage is reduced, but device size increases which is not feasible in size-limited applications
Solution Approach 1:
The offset cancellation function is segmented into two parts: an offset evaluation circuit that measures the offset voltage and stores it in a small offset capacitor, and a collected charge reduction circuitry that handles charge redistribution. This segmentation allows using a small capacitor instead of a large traditional capacitor while maintaining offset cancellation effectiveness.
Solution Approach 2:
The offset evaluation circuit acts as an intermediary that measures and stores the offset voltage in a compact offset capacitor. This intermediary mechanism enables offset cancellation without requiring large capacitors directly in the main signal path, thus reducing device size while maintaining precision.
2Measurement precision
If offset evaluation circuit is disconnected to reduce offset, then offset error is reduced, but charge redistribution introduces additional noise
Solution Approach 1:
The harmful charge redistribution noise is extracted and isolated by the collected charge reduction circuitry. This dedicated circuitry captures and manages the charge redistribution that occurs when the offset evaluation circuit is disconnected, preventing this charge from coupling into the main signal path and becoming noise.
Solution Approach 2:
The charge redistribution that would normally create noise is converted into a beneficial effect by the collected charge reduction circuitry. The circuitry captures this redistributed charge and redirects it to a safe path, transforming what would be harmful noise into a controlled charge flow that does not interfere with the signal.
3Measurement precision
If offset capacitor is used to store offset charge, then offset voltage is compensated, but additional circuit complexity is introduced
Solution Approach 1:
The offset evaluation circuit serves multiple functions: it evaluates the offset voltage, charges the offset capacitor with the offset charge, and the collected charge reduction circuitry simultaneously handles both offset cancellation and noise reduction. This multi-functionality reduces overall circuit complexity despite adding the offset capacitor.
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 solution effectively reduces offset voltage-related errors and noise in electronic integrators, improving signal quality and system accuracy, especially in applications with limited size constraints, such as those using photodiodes.
Implementation Method 1
an offset capacitor; an offset evaluation circuit operable to charge the offset capacitor with charge corresponding to an offset voltage of the amplifier
Implementation Method 2
an integration capacitor for collecting charge indicative of a level of the input signal
Implementation Method 3
the input signal is provided by a source comprising at least one photodiode, operable to generate electric charge in response to light impinging on the at least one photodiode
Data Source
AI summary
An integrator having an offset evaluation circuit and a collected charge reduction circuitry and method for using the integrator. The integrator includes an amplifier, operable to amplify an input signal, an integration capacitor for collecting charge indicative of a level of the input signal and an offset capacitor. The offset evaluation circuit is operable to charge the offset capacitor with charge corresponding to an offset voltage of the amplifier and the collected charge reduction circuitry is operable to collect charge resulting from disconnection of the offset evaluation circuit, thereby reducing an amount of charge and associated noise input to the amplifier.