Impedance Calibration Code Testing for Multi-Pad Semiconductor I/O
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Solution Overview
Problem
In semiconductor devices, impedance calibration is challenging due to signal loss and distortion when transmitting high-speed signals through transmission lines with different impedances, and the increasing number of input/output pads complicates impedance matching, especially when line cuts or shorts occur in code transmitting lines.
Innovation Solution
A semiconductor device with an impedance calibrating unit that generates and outputs an impedance calibration code, and a test code to a code transmitting line, allowing the impedance matching unit to perform impedance matching and serialize the test code for each pad, using multiplexers and serializers to adjust impedance and prevent signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of input/output pads increases to handle more signals, then the signal transmission capability improves, but the complexity of impedance matching and pad arrangement increases
Solution Approach 1:
The patent applies preliminary action by performing impedance calibration before normal signal transmission. The calibration code is transmitted through code transmitting lines to pre-adjust the impedance of OCDs and ODTs, ensuring that when actual signals are transmitted through the increased number of pads, the impedance matching is already optimized, thus handling the complexity proactively
Solution Approach 2:
The patent introduces an intermediary mechanism - the calibration code transmitting lines - that are separate from the actual signal transmission paths. These dedicated calibration lines carry test codes to various pads to measure and adjust impedance without interfering with normal signal flow, thus managing the complexity of multiple pads systematically
2Reliability
If code transmitting lines are used to transmit calibration codes to OCDs and ODTs in different areas, then the impedance calibration capability improves, but the risk of line cuts or shorts increases
Solution Approach 1:
The patent uses preliminary action by transmitting calibration codes through the code transmitting lines before normal operation to detect potential line cuts or shorts. The calibration process itself serves as a diagnostic function, identifying damaged lines early so they can be addressed before affecting actual signal transmission
Solution Approach 2:
The patent implements feedback by using the calibration code transmission as a diagnostic mechanism. When a calibration code is transmitted and not properly received or reflected, it provides feedback indicating a potential line cut or short, allowing the system to identify and respond to harmful factors in the transmission lines
3Speed
If high-speed signal transmission is implemented, then the data transmission rate improves, but signal loss due to impedance mismatch increases
Solution Approach 1:
The patent applies preliminary action by performing impedance calibration before high-speed signal transmission. The calibration code adjusts the impedance of OCDs and ODTs in advance, ensuring that when high-speed signals are transmitted, the impedance matching is already optimized, thereby preventing signal loss that would otherwise occur at high speeds
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the impedance parameters of OCDs and ODTs based on calibration results. The calibration code modifies impedance values to match the specific transmission line characteristics, enabling high-speed transmission without signal loss by optimizing the electrical parameters for each configuration
Data Source
AI summary
A semiconductor device includes a plurality of pads, where an external reference resistor is connected to a first one of the pads, an impedance calibrating unit configured to generate an impedance calibration code corresponding to an impedance of the reference resistor and output the impedance calibration code to a code transmitting line during a normal operating mode, and an impedance matching unit configured to perform an impedance matching operation in response to the impedance calibration code during the normal operating mode. The impedance calibrating unit is configured to output a test code to the code transmitting line in response to a test signal during a test operating mode. The impedance matching unit is configured to serialize the test code to output the serialized test code to each of the other pads in response to the test signal during the test operating mode.