Semiconductor Pad Swapping for Sequential Impedance Calibration
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Solution Overview
Problem
Existing semiconductor apparatuses face challenges in simultaneous calibration of termination resistance due to impedance mismatching and external noise, particularly when multiple semiconductor chips share a common external reference resistor.
Innovation Solution
A semiconductor circuit and apparatus that utilize a swapping circuit to efficiently couple internal signals to pads, allowing for sequential calibration of semiconductor chips using a common external reference resistor, thereby avoiding the need for multiple external reference resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple semiconductor chips are coupled to share a common external reference resistor for calibration, then the quantity of external reference resistors is reduced and cost is lowered, but the chips cannot perform calibration simultaneously due to signal conflicts
Solution Approach 1:
The patent implements dynamic signal path switching within each semiconductor chip using swapping circuits. Each chip can dynamically select between different signal paths: one path connects to the common external reference resistor for calibration mode, while another path connects to an internal reference resistor for normal operation mode. This dynamic switching capability allows multiple chips to share the common external reference resistor without signal conflicts, as only one chip at a time needs to be in calibration mode, thereby reducing the number of external reference resistors needed while maintaining calibration productivity.
Solution Approach 2:
The patent employs periodic calibration operations where semiconductor chips take turns performing calibration sequentially. The swapping circuit controls the timing of calibration operations, allowing one chip to calibrate against the common external reference resistor while other chips remain in normal operation mode using their internal reference resistors. This periodic action eliminates signal conflicts by ensuring that calibration signals from multiple chips do not occur simultaneously, thus enabling cost-effective sharing of the common external reference resistor without compromising overall system calibration throughput.
2Measurement precision
If a semiconductor chip uses an on-die termination circuit for impedance matching, then signal transmission precision is improved, but the chip requires external reference resistors for calibration which increases device complexity and cost
Solution Approach 1:
The patent merges the functions of internal reference resistors and external reference resistors into a unified calibration system. Each semiconductor chip contains an internal reference resistor that can be coupled to pads, and when multiple chips are used, they share a common external reference resistor. The swapping circuit enables seamless switching between these reference sources, allowing the internal reference resistor to serve as a standalone calibration reference when external calibration is not needed, thereby reducing the need for external calibration components and simplifying the overall device complexity while maintaining impedance matching precision.
Solution Approach 2:
The patent implements self-service calibration capability within each semiconductor chip using an on-die termination circuit with an internal reference resistor. The swapping circuit allows the chip to autonomously select between calibrating against its own internal reference resistor or against a shared external reference resistor. This self-service approach eliminates the need for complex external calibration equipment and reduces device complexity by making the calibration function self-contained within each chip, while still achieving precise impedance matching through the termination circuit.
3Quantity of substance
If semiconductor chips perform calibration using a common external reference resistor, then cost is reduced, but signal distortion may occur due to impedance mismatching and external noise affecting multiple chips simultaneously
Solution Approach 1:
The patent segments the calibration function into individual chip-level operations rather than simultaneous multi-chip calibration. Each semiconductor chip has its own swapping circuit that independently controls calibration timing and signal paths. When one chip performs calibration using the common external reference resistor, other chips remain in normal operation mode with their swapping circuits directing signals away from the external reference resistor connection. This segmentation of calibration operations in time and space prevents signal conflicts and reduces susceptibility to external noise and impedance mismatching, as each chip calibrates independently rather than all chips simultaneously affecting the same external reference resistor.
Data Source
AI summary
A semiconductor circuit includes a first pad, a second pad, swapping circuit, and an internal circuit. The internal circuit receives a first external signal and a second external signal, and generates a first internal signal and a second internal signal. Based on master information and swapping information, the swapping circuit couples the internal circuit to one of first and second pads to provide a path through which the first internal signal is output and a path through which the first external signal is received, and couples the internal circuit to the other of the first and second pads to provide a path through which the second internal signal is output and a path through which the second external signal is received.