Impedance Calibration Circuit for Multi-Termination Memory Interfaces
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Solution Overview
Problem
Existing impedance calibration circuits for semiconductor apparatuses are cumbersome and time-consuming due to the need for multiple terminating circuits with different impedance specifications, especially when dealing with PVT variations.
Innovation Solution
The proposed impedance calibration circuit includes a first and second impedance calibration part, which generate impedance calibration code sets to adjust the impedance of terminating resistors to specific target values, using a single external resistor and a reference resistance unit, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple terminating circuits with different impedance specifications are used to satisfy diverse termination requirements, then the adaptability to different memory apparatus specifications is improved, but the device complexity and calibration time increase
Solution Approach 1:
The patent implements a universal impedance calibration circuit that can calibrate multiple terminating circuits (first terminating circuit with first target impedance and second terminating circuit with second target impedance) using a single external resistor. The calibration circuit includes a switching mechanism that selectively connects different terminating circuits to the external resistor, allowing one external resistor to serve multiple calibration functions that would traditionally require separate resistors for each terminating circuit.
Solution Approach 2:
The patent merges the calibration functions for multiple terminating circuits into a single integrated calibration process. By combining the calibration operations of the first and second terminating circuits into one unified calibration circuit architecture, the system reduces the number of separate external resistors needed while maintaining the ability to independently calibrate each terminating circuit to its specific target impedance.
2Manufacturing precision
If multiple external resistors are used for calibrating different terminating circuits, then the manufacturing precision of impedance calibration is improved, but the device complexity and area increase
Solution Approach 1:
The patent makes the external resistor multi-functional by designing a switching mechanism that allows a single external resistor to be sequentially connected to different terminating circuits during calibration. This eliminates the need for multiple external resistors, thereby reducing the overall circuit area while maintaining calibration precision through controlled switching between different calibration targets.
Solution Approach 2:
The patent introduces dynamic switching capability that allows the external resistor to be selectively connected to different terminating circuits based on calibration requirements. This dynamic reconfiguration enables one resistor to replace multiple static resistors, reducing the total component count and circuit area while preserving the ability to achieve precise impedance calibration for each terminating circuit.
3Manufacturing precision
If separate impedance calibration processes are performed for each terminating circuit, then the manufacturing precision of each calibration is improved, but the calibration time increases
Solution Approach 1:
The patent enables continuous calibration operation by implementing a switching mechanism that allows the calibration process to proceed sequentially across multiple terminating circuits without interrupting the overall calibration flow. The calibration signal can continuously transition from calibrating the first terminating circuit to the second terminating circuit, eliminating idle time between separate calibration processes while maintaining calibration accuracy through systematic switching control.
Solution Approach 2:
The patent performs preliminary configuration of the calibration circuit to establish switching paths and control logic before actual calibration begins. By pre-configuring the switching mechanism and calibration sequence, the system prepares for rapid sequential calibration of multiple terminating circuits, reducing the total calibration time while ensuring each circuit receives proper calibration attention through pre-planned switching operations.
Data Source
AI summary
A first impedance calibration part configured to perform a first impedance calibration operation of generating a first impedance calibration code set for adjusting an impedance of a first terminating resistor to a first target value, with reference to an external resistor having a first resistance value. A second impedance calibration part configured to perform a second impedance calibration operation of generating a second impedance calibration code set for adjusting an impedance of a second terminating resistor to a second target value, with reference to a reference resistance unit, a resistance value of which is set to a second resistance value according to a part of the first impedance calibration code set.