Shared ZQ Resistance Identification for Memory Bus Impedance Calibration
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Solution Overview
Problem
Impedance mismatches in semiconductor devices lead to decreased transmission speed and distorted data due to external noise and varying operating conditions, causing setup/hold failures and errors in data reception.
Innovation Solution
Incorporating programmable termination components with adjustable impedance that can be calibrated based on voltage measurements to match the impedance of the data bus, and using a ZQ ID mode to identify and arbitrate shared external resistances among memory devices for calibration, ensuring optimal impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance matching is performed using fixed termination components, then the impedance can be matched under specific operating conditions, but the impedance matching deteriorates when operating conditions change (temperature, process variations, noise)
Solution Approach 1:
The patent applies dynamics by replacing fixed termination components with programmable termination components whose impedance can be dynamically adjusted. The system measures voltage at a calibration node and programmatically sets the termination impedance to achieve optimal matching under varying operating conditions, making the impedance adaptation dynamic rather than static.
Solution Approach 2:
The patent changes the impedance parameter of the termination component programmatically based on measured voltage conditions. By adjusting the termination impedance parameter in response to operating condition changes (temperature, process variations, noise), the system maintains optimal impedance matching across different scenarios.
2Device complexity
If multiple memory devices share a common external resistance for calibration, then the device complexity is reduced, but contention occurs during calibration operations when multiple devices need to use the shared resistance simultaneously
Solution Approach 1:
The patent applies preliminary action by implementing an arbitration mechanism that determines which memory device gets to use the shared external resistance first. Before calibration operations begin, the system arbitrates and assigns exclusive access rights to one device at a time, preventing contention and ensuring reliable calibration without requiring separate external resistances for each device.
3Speed
If the swing of transmitted signals is decreased to increase operational speeds, then the transmission speed increases, but the negative effect of external noise and impedance mismatch increases
Solution Approach 1:
The patent applies feedback by measuring the voltage at a calibration node and using this measurement to programmatically adjust the termination impedance. This closed-loop feedback mechanism ensures that even with small signal swings at high speeds, the impedance remains optimally matched, minimizing reflections and maintaining signal integrity despite external noise.
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 solution reduces signal reflections and errors by dynamically adjusting impedance to match changing operating conditions, improving data transmission speed and accuracy by avoiding impedance mismatches and contention during calibration operations.
Implementation Method 1
a calibration circuit coupled to the communication channel and coupled to the programmable termination component. The calibration circuit is configured to measure a voltage at a calibration node
Implementation Method 2
The programmable termination component has an impedance that is programmable via a communication channel. The programmable termination component is calibrated to an impedance of a data bus by the calibration circuit
Data Source
AI summary
Apparatuses and methods for identifying memory devices of a semiconductor device sharing an external resistance are disclosed. A memory device of a semiconductor device may be set in an identification mode and provide an identification request to other memory devices that are coupled to a common communication channel. The memory devices that are coupled to the common communication channel may share an external resistance, for example, for calibration of respective programmable termination components of the memory devices. The memory devices that receive the identification request set a respective identification flag which can be read to determine which memory devices share an external resistance with the memory device having the set identification mode.