DQ Output Driver Calibration Using Per-Pad Reference Resistors
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Solution Overview
Problem
ZQ calibration in semiconductor devices requires a long time to calculate adjustment values and is difficult to achieve accurately due to variations in transistor characteristics across output drivers connected to different DQ pads.
Innovation Solution
Providing a reference resistor in each OCD circuit for each DQ pad allows for simultaneous calibration of output drivers, reducing the time and complexity of ZQ calibration by setting resistance values independently for each output driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ZQ calibration is performed using a single reference resistor for all output drivers, then device complexity is reduced, but calibration time increases and measurement precision deteriorates
Solution Approach 1:
The patent divides the single reference resistor into multiple reference resistors, with each reference resistor corresponding to a specific output driver. This segmentation allows each output driver to be calibrated independently and simultaneously, eliminating the sequential calibration process and significantly reducing total calibration time while maintaining device complexity at an acceptable level.
Solution Approach 2:
The patent assigns different reference resistors to different output drivers based on their specific location and characteristics. Each reference resistor is optimized for its corresponding output driver, enabling precise local calibration that accounts for variations in transistor characteristics across different DQ pads, thereby improving measurement precision.
2Device complexity
If ZQ calibration is performed using a single reference resistor for all output drivers, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
By segmenting the single reference resistor into multiple reference resistors, each dedicated to a specific output driver, the patent enables independent calibration measurements for each driver. This segmentation allows for precise measurement of each output driver's characteristics without interference from others, significantly improving calibration accuracy.
Solution Approach 2:
The patent implements local quality by providing each output driver with its own optimized reference resistor. This allows the calibration circuit to account for local variations in transistor characteristics across different DQ pads, achieving high measurement precision for each individual output driver rather than using a one-size-fits-all approach.
3Device complexity
If ZQ calibration calculates adjustment values sequentially, then device complexity is reduced, but productivity decreases
Solution Approach 1:
The patent segments the calibration process into independent parallel operations, with each reference resistor and its corresponding output driver forming an independent calibration unit. This segmentation enables simultaneous calibration of multiple output drivers, dramatically increasing calibration throughput while keeping control complexity manageable through standardized calibration procedures.
Solution Approach 2:
The patent merges multiple calibration operations that were previously performed sequentially into a single simultaneous calibration cycle. By coordinating the calibration of multiple output drivers at the same time using multiple reference resistors, the system achieves high productivity without requiring complex coordination logic, as each calibration unit operates independently.
Data Source
AI summary
A semiconductor device includes a first pad, a second pad, a first output driver provided for the first pad and configured to output a first transmission signal to the first pad, a second output driver provided for the second pad and configured to output a second transmission signal to the second pad, a register that stores first and second calibration values, a first reference resistor for the first pad and having a resistance value that is set according to the first calibration value, a second reference resistor for the second pad and having a resistance value that is set according to the second calibration value, a first setting circuit configured to calibrate a resistance value of the first output driver using the first reference resistor, and a second setting circuit configured to calibrate a resistance value of the second output driver using the second reference resistor.