Differential Offset Adjustment Circuit Using Variable Current Sources
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Solution Overview
Problem
Differential amplifiers suffer from offset errors due to physical design and manufacturing process mismatches, affecting their performance, and existing solutions require complex operational amplifiers for adjustment.
Innovation Solution
A differential signal offset adjustment circuit using transistors and variable current sources, controlled by a control circuit, adjusts the cross-point of differential signals to compensate for offset errors, utilizing a bandgap circuit for stable reference currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential amplifier is used to read data from memory array, then the reading function is achieved, but offset errors occur due to physical design and manufacturing process mismatches
Solution Approach 1:
The patent adjusts the offset of differential signals by changing current parameters. Specifically, it uses current sources and transistors to modify the current flowing through different branches of the differential amplifier, thereby changing the electrical parameters to compensate for manufacturing mismatches and threshold voltage variations.
Solution Approach 2:
The patent implements a feedback mechanism where the offset adjustment circuit monitors the differential signals and automatically adjusts the current distribution to compensate for detected offset errors. This closed-loop approach ensures that offset variations due to manufacturing processes are continuously corrected.
2Measurement precision
If existing offset adjustment solutions are implemented, then offset errors are compensated, but the circuit complexity increases due to requirement of complex operational amplifiers
Solution Approach 1:
The patent extracts the offset adjustment function from the main differential amplifier circuit, implementing it as a separate, dedicated adjustment circuit. This separation allows the main amplifier to focus on signal amplification while the extracted adjustment circuit handles offset compensation, reducing overall system complexity.
Solution Approach 2:
The patent replaces complex operational amplifiers with simpler current sources and transistor-based adjustment circuits. These simpler components achieve the same offset compensation function with fewer elements, reducing circuit complexity while maintaining effectiveness.
3Measurement precision
If more components are added to adjust offset, then offset adjustment capability is improved, but the circuit area increases
Solution Approach 1:
The patent designs adjustment components that serve multiple functions. The current sources and transistors used for offset adjustment also contribute to signal amplification and biasing, making them multi-functional elements that reduce the need for additional dedicated components.
Solution Approach 2:
The patent merges the offset adjustment function with the existing differential amplifier structure by integrating current sources and transistors into the same circuit block. This consolidation allows offset adjustment without requiring separate dedicated components, thereby saving circuit area.
Data Source
AI summary
The present invention provides a differential signal offset adjustment circuit, wherein first and second transistors are respectively coupled between a power supply line and a first current source, and between the power supply line and a second current source. First and second resistors are respectively coupled between the first transistor and a first variable current source, and between the second transistor and a second variable current source. Third and fourth transistors are respectively coupled between a third resistor and a third current source, and between a fourth resistor and a fourth current source, and have input terminals respectively coupled to the first and second resistors. Fifth and sixth transistors are respectively coupled between the power supply line and a fifth current source, and between the power supply line and a sixth current source, and have input terminals respectively coupled to the third and fourth transistors. A fifth resistor is coupled between the third and fourth current sources.