Calibration Circuit Reset Switching for Stable Impedance Matching
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Solution Overview
Problem
Existing calibration circuits for semiconductor devices generate noise during transistor switching, leading to inaccurate impedance matching and disrupted high-speed data transfer due to large changes in current driving capability during state transitions.
Innovation Solution
A calibration circuit that inactivates all transistors to their initial state before setting them to the desired state, using a comparator and counter to generate impedance control signals, ensuring stable potential levels and minimizing noise by synchronizing transistor switching with a mask signal, thus maintaining constant potential differences for accurate impedance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transistors are switched one by one according to binary counter signal to adjust impedance, then impedance matching precision is improved, but noise is generated during switching transitions
Solution Approach 1:
The patent applies preliminary action by resetting all transistors to their initial state before switching them to the desired state. The reset signal is generated in advance by the control circuit before the impedance adjustment switching occurs, ensuring that potential differences remain constant during the transition. This prevents noise generation while maintaining impedance matching precision.
2Object-generated harmful factors
If transistors are switched using decimal system to reduce switching noise, then noise is reduced, but the number of driver circuits increases
Solution Approach 1:
The patent changes the control parameter from binary to decimal system for transistor switching. By using decimal-coded control signals instead of binary, the number of switching transitions is reduced, which minimizes noise generation. The control circuit generates decimal control signals that directly switch transistors to desired states without requiring multiple intermediate switching steps.
3Measurement precision
If impedance is adjusted by switching transistor states during data transfer, then impedance matching is achieved, but potential levels become unstable causing noise
Solution Approach 1:
The patent applies preliminary action by generating a reset signal before impedance adjustment switching occurs. This reset signal returns all transistors to their initial state, establishing stable potential levels in advance. The control circuit then switches transistors to the desired state while maintaining constant potential differences, ensuring both impedance matching and potential stability.
Solution Approach 2:
The patent uses feedback by monitoring the states of transistors and adjusting control signals accordingly. The control circuit receives feedback about transistor states and generates appropriate reset and control signals to maintain stable potential levels during impedance adjustment, preventing noise generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures stable output levels and accurate impedance matching, preventing noise-induced errors and enabling high-speed data transfer by maintaining consistent potential levels during transistor switching.
Implementation Method 1
a comparator adapted to compare between a potential at the calibration terminal and a reference potential
Implementation Method 2
a counter adapted to perform a count operation in response to an output of the comparator
Implementation Method 3
a control circuit adapted to output an impedance control signal in response to a count output and a mask signal from the counter, the impedance control signal used for controlling impedance of the replica circuit
Data Source
AI summary
Impedance adjusting transistors are once inactivated on every occasion of changing an impedance adjusting code. After restoring the potential to an initially set potential by once inactivating the impedance adjusting transistors, the state of the transistors is switched according to the impedance adjusting code. By starting the potential from the initially set potential at the time of switching the state of the transistors, no switching noise is generated. Since no switching noise is generated, a comparator always carries out stable comparison and judgment and thus there is obtained a calibration circuit that ensures stable outputs.