Impedance Tuning Circuit Using Reused Calibration Codes
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Solution Overview
Problem
Conventional impedance tuning circuits require hundreds of cycles to adjust output and termination impedances, leading to performance deterioration due to process, voltage, and temperature variations, causing signal distortion between integrated circuits.
Innovation Solution
An impedance tuning circuit with a calibration unit that generates initial pull-up and pull-down codes during an initial impedance tuning operation and a post-processing unit that uses these codes to generate final codes during subsequent operations, reducing the impedance tuning time by completing the process within two clock cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional impedance tuning circuits perform calibration operation using external resistor, then impedance matching accuracy is improved, but impedance tuning time increases to hundreds of cycles
Solution Approach 1:
The patent performs a calibration operation during an initial impedance tuning operation to generate initial pull-up and pull-down codes. These codes are then reused during subsequent impedance tuning operations, eliminating the need to repeat the time-consuming calibration process. This preliminary action resolves the contradiction by establishing accurate impedance codes once, then reusing them to maintain both accuracy and speed in ongoing operations.
Solution Approach 2:
The patent implements a periodic action by performing the calibration operation only during the initial impedance tuning operation, and then reusing the generated codes during subsequent operations. This periodic approach allows the system to achieve high impedance matching accuracy when needed while minimizing the time spent on calibration in regular operations, thus resolving the time-accuracy tradeoff.
2Reliability
If impedance tuning operation is performed to adjust output impedance and termination impedance, then signal distortion is reduced, but system performance deteriorates during the tuning process
Solution Approach 1:
The patent performs the calibration operation in advance during the initial impedance tuning operation, generating codes that are then reused during subsequent operations. This preliminary action ensures that impedance matching is established before regular operations begin, preventing signal distortion while minimizing the impact on system performance during normal operation since the codes are reused rather than recalculated.
Solution Approach 2:
The patent creates a copy of the calibration results (initial pull-up and pull-down codes) generated during the initial impedance tuning operation. These copied codes are then used during subsequent impedance tuning operations, allowing the system to maintain signal quality without repeating the full calibration process, thus preserving system performance while ensuring reliable impedance matching.
3Measurement precision
If calibration operation is performed during each impedance tuning operation, then impedance accuracy is maintained, but operation complexity increases
Solution Approach 1:
The patent implements periodic action by performing the calibration operation only during the initial impedance tuning operation, and then reusing the generated codes during subsequent operations. This approach maintains impedance accuracy by establishing correct codes initially, while reducing operation complexity by eliminating the need to repeat calibration in every subsequent operation.
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
The solution significantly reduces impedance tuning time, preventing signal distortion and maintaining system performance despite PVT variations, by using initial codes generated during the initial tuning operation to adjust impedances in subsequent operations.
Implementation Method 1
a first comparator configured to compare a voltage at a first node between the first pull-up array and the external resistor with a reference voltage
Data Source
AI summary
An impedance tuning circuit includes a calibration unit and a post-processing unit. The calibration unit generates an initial pull-up code and an initial pull-down code by performing a calibration operation using an external resistor during an initial impedance tuning operation. The post-processing unit outputs the initial pull-up code and the initial pull-down code as a final pull-up code and a final pull-down code during the initial impedance tuning operation, and generates the final pull-up code and the final pull-down code by using the initial pull-up code and the initial pull-down code during a subsequent impedance tuning operation.