Impedance Calibration Circuit With Sensing Node Connection Detection
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Solution Overview
Problem
Existing impedance adjusting circuits in memory devices lack a connection detection function, which can render zero quotient (ZQ) calibration ineffective when the connection of the sensing node is abnormal.
Innovation Solution
The impedance adjusting circuit includes a sensing node, a pull-up impedance generator, a ZQ calibrating circuit, and a controller. The controller enables a detecting mode to detect the sensing voltage and performs ZQ calibration or trimming operations based on whether the sensing voltage is within a default voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the impedance adjusting circuit performs ZQ calibration based on sensing voltage without connection detection, then the calibration process is simple, but the calibration becomes ineffective when the sensing node connection is abnormal
Solution Approach 1:
The circuit performs connection detection before executing ZQ calibration by comparing the sensing voltage with reference voltages. This preliminary detection ensures that calibration is only performed when the sensing node is properly connected, preventing ineffective calibration operations and improving overall calibration reliability.
Solution Approach 2:
The patent introduces reference voltage generators and comparison circuits as intermediary elements between the sensing node and the calibration process. These intermediaries enable the controller to detect connection status by comparing sensing voltage against reference voltages, thereby determining whether to proceed with calibration.
2Loss of energy
If the controller always performs ZQ calibration operation, then the impedance adjustment is maintained, but energy is wasted when the sensing node connection is abnormal
Solution Approach 1:
The controller uses feedback from the voltage comparison result to decide whether to perform ZQ calibration. When the sensing voltage falls outside the reference voltage range indicating abnormal connection, the controller skips the calibration operation, thereby avoiding unnecessary energy consumption while maintaining impedance adjustment accuracy through conditional execution.
Solution Approach 2:
The circuit changes the operational parameter (calibration execution) based on the detected connection status. By monitoring the sensing voltage parameter and comparing it with reference voltages, the system dynamically adjusts whether to perform calibration, optimizing energy usage while ensuring accurate impedance adjustment only when connections are proper.
Data Source
AI summary
An impedance adjusting circuit is provided. The impedance adjusting circuit of the disclosure includes a sensing node, a pull-up impedance generator, a zero quotient (ZQ) calibrating circuit and a controller. The pull-up impedance generator is coupled between an external voltage and the sensing node. The controller enables a detecting mode in response to a detecting command, and detect a sensing voltage on the sensing node in the detecting mode. When the sensing voltage is in a default voltage range, the controller controls the ZQ calibrating circuit to perform a ZQ calibrating operation on the pull-up impedance generator. When the sensing voltage is out of the default voltage range in the detecting mode, the controller provides a trimming command to the ZQ calibrating circuit. The ZQ calibrating circuit provides a build-in trim code to the pull-up impedance generator in response to the trimming command.