Current Amplifier Offset Correction with Switched Feedback Hold
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Solution Overview
Problem
Current current amplifiers suffer from offset issues due to process variations during production, leading to undesirable output currents that affect the amplification of input signals.
Innovation Solution
A circuit and method are introduced that utilize a controlled current source and switching devices to form a control loop, regulating the offset to a minimum by setting a current value, with a capacitor for storing control voltage and a constant current source to compensate for the offset, ensuring the output current remains constant during signal amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current amplifier is used to amplify small input currents, then the amplification capability is improved, but offset current due to process variations deteriorates the output accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the output current of the current amplifier is fed back to a controlled current source. The controlled current source adjusts its output based on the feedback signal to compensate for offset current. This closed-loop feedback system continuously monitors and corrects the offset, improving output current accuracy despite process variations.
Solution Approach 2:
The patent changes the parameter of the controlled current source (its output current) dynamically to compensate for offset. By adjusting the current parameter of the controlled current source based on feedback, the system adapts to process variations and maintains accurate output current.
2Measurement precision
If a controlled current source with switching device is added to regulate offset, then the offset correction capability is improved, but the circuit complexity increases
Solution Approach 1:
The controlled current source is designed to perform multiple functions: it acts as both an offset compensation element and a signal source. The switching device serves dual purposes by controlling both the feedback path and the compensation current path. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in circuit complexity.
3Measurement precision
If the controlled current source is connected in a closed loop for regulation, then the offset regulation performance is improved, but the response time for signal amplification is increased
Solution Approach 1:
The patent employs periodic switching of the switching device to balance offset regulation and signal amplification. During specific periods, the switch connects the feedback path for offset regulation. During other periods, it prioritizes signal amplification. This periodic action allows the system to achieve both offset regulation performance and acceptable response time by alternating between these two modes.
Data Source
AI summary
A circuit and a method for correcting an offset is provided that includes a current amplifier and an adjusting circuit for correcting an offset of an output current of the current amplifier. Wherein the adjusting circuit has a controlled current source, an output of the controlled current source is connected to the current amplifier for impressing an output current of the controlled current source in the current amplifier, an input of the controlled current source to form a regulation element of a control loop is connected by a first switching device of the adjusting circuit to an output of the current amplifier and to form a holding element is disconnected from the output of the current amplifier by the first switching device. The controlled current source, acting as a regulation element in the control loop, is set up to regulate the offset to a minimum by setting of a current value of the output current, and the controlled current source, acting as a holding element, is set up to hold the current value, associated with the minimum, of the output current.