Shared Impedance Calibration Circuit for Multi-Transceiver Matching
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Solution Overview
Problem
High-speed transceivers face impedance mismatch issues due to variations in resistances caused by process, voltage, and temperature changes, leading to signal reflections and the need for numerous calibration pins and external resistors, increasing chip and assembly costs.
Innovation Solution
A calibration circuit that uses a single calibration pin and external resistor to calibrate all transceivers by selecting combinations of identical resistance components through a feedback system, generating calibration signals to match target impedances, thereby reducing the number of pins and silicon area required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each transceiver section uses separate calibration pins and external resistors for impedance matching, then impedance matching precision is improved, but device complexity and assembly cost increase
Solution Approach 1:
The patent merges multiple calibration functions into a single calibration section. The first calibration section shares the first external resistor and calibration pin with multiple transceiver sections, eliminating the need for separate calibration components for each transceiver. This combining approach reduces device complexity while maintaining impedance matching capability through shared calibration resources.
Solution Approach 2:
The calibration section is designed with universal functionality to serve multiple transceiver sections simultaneously. The single calibration pin and external resistor can calibrate impedance for multiple different transceiver sections, making the calibration mechanism multi-functional rather than dedicated to a single transceiver, thus reducing the overall number of components required.
2Manufacturing precision
If multiple external resistors and calibration pins are used for each transceiver section, then calibration accuracy is improved, but manufacturing cost and assembly cost increase
Solution Approach 1:
Multiple calibration functions are merged into a single calibration section that shares external resistors and calibration pins across multiple transceiver sections. This reduces the total number of external components that need to be manufactured and assembled, thereby lowering both manufacturing cost and assembly cost while preserving calibration accuracy through the shared calibration mechanism.
Solution Approach 2:
The calibration section is designed to universally calibrate multiple transceiver sections using a single set of external resistors and calibration pins. This multi-functional design eliminates the need for separate calibration components for each transceiver, reducing component count and associated costs while maintaining the ability to achieve accurate calibration across all sections.
3Measurement precision
If separate calibration circuits are provided for each transceiver, then calibration precision is improved, but silicon area consumption increases
Solution Approach 1:
The patent merges multiple calibration circuits into a single calibration section that serves multiple transceiver sections. By combining the calibration functionality and sharing common components such as external resistors and control logic, the silicon area required for calibration is significantly reduced compared to having separate dedicated calibration circuits for each transceiver, while calibration precision is maintained through the shared calibration mechanism.
Data Source
AI summary
A calibration circuit including a plurality of first resistance components, a plurality of second resistance components, and a first feedback system is provided. The first feedback system selects M1 first resistance components and N1 second resistance components so that a first combination of the M1 first resistance components and the N1 second resistance components has a first predetermined relationship with the impedance of a first resistor. The first feedback system selects M2 first resistance components and N2 second resistance components so that a second combination of the M2 first resistance components and the N2 second resistance components has a second predetermined relationship with the impedance of the first resistor. Based on the values of M1, N1, M2, N2, and a target impedance, the first feedback system generates a first set of calibration signals for a plurality of third resistance components and generates a second set of calibration signals for a plurality of fourth resistance components.