Current Amplifier Offset Correction Using a Held Control Current
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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 utilizing a controlled current source with a switching device and capacitor to form a regulation and holding element, which connects to the current amplifier to regulate and hold the output current at a minimum offset, ideally zero, by using a control loop to adjust and maintain a constant output current.
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 holding element. The same circuit component regulates offset during calibration and maintains the corrected output current during normal operation, reducing the need for separate dedicated components and thereby limiting complexity increase.
Solution Approach 2:
The patent introduces dynamic switching between different operational modes using switching devices. The circuit dynamically transitions between calibration mode (where offset is regulated) and normal operation mode (where the corrected state is held). This dynamic approach allows complex functionality to be achieved through time-multiplexed operation of shared components.
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.