Differential Input Circuit Offset Calibration With Coarse and Fine Codes
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Solution Overview
Problem
Differential input circuits in semiconductor devices face operational issues due to offset values caused by transistor mismatches, leading to abnormal operations when voltage differences between input signals are not sufficient, necessitating effective calibration methods to ensure normal functioning.
Innovation Solution
A semiconductor device and method for calibrating differential input circuits through a combination of coarse and fine calibration processes, utilizing comparison circuits, offset control circuits, and adjusting transistor drivability with specific strengths to compensate for offset values, ensuring accurate signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential input circuit is designed with high sensitivity to detect small voltage differences, then the circuit can operate with low input signal margins, but transistor mismatches cause offset values that lead to abnormal operations when voltage differences are insufficient
Solution Approach 1:
The patent applies preliminary action by performing offset calibration before normal operation. The calibration circuit pre-adjusts the differential input circuit to compensate for transistor mismatches, storing calibration data that is later used to correct offset errors during actual operation, ensuring reliable detection even with small voltage differences
Solution Approach 2:
The patent changes parameters by adjusting transistor gate voltages during calibration to optimize the differential input circuit's offset characteristics. The calibration circuit varies gate voltage parameters to find optimal settings that minimize offset errors, improving both sensitivity and reliability
2Reliability
If offset calibration is performed to compensate for transistor mismatches, then circuit operation reliability improves, but device complexity increases due to additional calibration circuits and procedures
Solution Approach 1:
The patent merges the calibration function with the existing differential input circuit structure. The calibration circuit shares transistors and components with the main signal path, combining calibration and signal processing functions to reduce overall device complexity while maintaining calibration effectiveness
Solution Approach 2:
The differential input circuit performs self-calibration by using its own internal components for the calibration process. The calibration circuit generates test signals and measures offset errors using the same transistor pairs that will be used during normal operation, eliminating the need for external calibration equipment and reducing system complexity
Data Source
AI summary
According to an embodiment, a semiconductor device includes a differential input circuit suitable for receiving first and second input signals respectively inputted to first and second input transistors, and outputting an output signal; a comparison circuit suitable for generating a first judge signal by comparing the output signal with a first comparison voltage, and generating a second judge signal by comparing the output signal with a second comparison voltage, in a calibration mode; an offset control circuit suitable for adjusting coarse codes and fine codes, according to the first and second judge signals; and an offset adjusting circuit suitable for adjusting a drivability of each of the first and second input transistors by a first strength, according to the coarse codes, and adjusting the drivability of each of the first and second input transistors by a second strength smaller than the first strength, according to the fine codes.