Differential Amplifier Offset Calibration Using Dynamic Routing
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Solution Overview
Problem
Differential amplifier circuits introduce DC offsets due to transistor mismatches, which contribute to errors in operational amplifiers alongside 1/f noise and drift.
Innovation Solution
The amplifier circuit incorporates multiple transistors, input routing circuits, and output routing circuits controlled by control signals to dynamically connect transistors to input or output terminals or a calibration circuit, allowing for selective connection and calibration to reduce offset voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If differential amplifier circuits are used to amplify the difference between two input voltages, then amplification function is achieved, but DC offset is introduced due to transistor mismatches
Solution Approach 1:
The patent applies preliminary action by performing offset calibration before normal amplification operation. The calibration circuit pre-determines the offset voltage caused by transistor mismatches, and this calibration data is stored and used during subsequent amplification to compensate for the DC offset, thereby eliminating the harmful effect before it degrades signal accuracy
Solution Approach 2:
The patent introduces a calibration circuit as an intermediary component that measures and characterizes the offset voltage separately. This calibration circuit acts as a mediator between the differential amplifier and the output, providing correction information that compensates for the DC offset without interfering with the main amplification function
2Power
If transistor pairs are used in differential amplifier, then differential amplification is achieved, but offset voltage occurs due to threshold voltage differences
Solution Approach 1:
The patent implements feedback by using the calibration circuit to continuously monitor and determine the offset voltage generated by transistor threshold voltage differences. This offset information is fed back to the control logic, which then applies appropriate compensation signals to counteract the offset, thereby maintaining high measurement precision despite transistor mismatches
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the compensation parameters based on the calibrated offset voltage. The control logic modifies the operating parameters of the differential amplifier using the calibration data, changing the electrical parameters to compensate for threshold voltage differences and maintain output accuracy
3Measurement precision
If dynamic offset calibration is implemented, then DC offset is reduced, but circuit complexity increases
Solution Approach 1:
The patent applies universality by designing the calibration circuit to serve multiple functions: it characterizes offset voltage, stores calibration data, and provides compensation signals. This multi-functional approach reduces the need for separate dedicated components for each function, thereby limiting the increase in circuit complexity while achieving dynamic offset calibration
Solution Approach 2:
The patent implements self-service by enabling the amplifier circuit to automatically perform offset calibration and compensation without external intervention. The calibration circuit autonomously determines offset voltages, and the control logic automatically applies corrections, making the system self-regulating and reducing the need for external calibration equipment or manual adjustment mechanisms
Data Source
AI summary
An amplifier circuit includes multiple transistors, a set of input routing circuits, and a set of output routing circuits. Each output routing circuit corresponds to an input routing circuit. Each input routing circuit and its corresponding output routing circuit are controlled by one or more control signals. Each input routing circuit is configured to selectively connect each transistor of a transistor pair to a first input terminal of the amplifier circuit, a second input terminal of the amplifier circuit, or a third input terminal of the amplifier based on a value of the one or more control signals. Each output routing circuit is configured to selectively connect each transistor of the transistor pair to a first output terminal of the amplifier circuit, a second output terminal of the amplifier circuit, or a calibration circuit based on the value of the one or more control signals.