Voltage-Mode Driver Impedance Calibration
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Solution Overview
Problem
Existing voltage-mode drivers face challenges in calibrating output impedance to match low-impedance transmission lines effectively, leading to increased power consumption and reduced calibration resolution due to the need to activate multiple driver slices.
Innovation Solution
The system employs a method of dividing driver slices into coarse and fine slices, performing coarse and fine calibration to adjust output resistance, using a processor to set control codes and activate slices to achieve the desired impedance while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple driver slices are activated to calibrate output impedance, then impedance matching precision is improved, but power consumption increases
Solution Approach 1:
The driver is divided into multiple driver slices that can be independently activated. The calibration process selectively enables specific slices based on the desired impedance value, allowing precise impedance matching while minimizing the number of active slices to reduce power consumption.
Solution Approach 2:
The system dynamically adjusts the number and configuration of active driver slices during calibration based on measured impedance values. The calibration algorithm determines the optimal combination of slices to activate, changing the system configuration adaptively to achieve target impedance while optimizing power usage.
2Measurement precision
If more driver slices are activated to improve calibration resolution, then calibration resolution is improved, but driver power consumption increases
Solution Approach 1:
By segmenting the driver into multiple independent slices, the system can activate only the necessary number of slices required to achieve the desired calibration resolution. This avoids the need to activate all slices, thereby maintaining high calibration resolution while minimizing power consumption.
Solution Approach 2:
The calibration algorithm changes the parameter of slice activation status (on/off) to optimize the balance between calibration resolution and power consumption. It determines the minimum number of slices needed to achieve acceptable resolution and activates only those slices.
3Measurement precision
If driver slices are split and selectively enabled/disabled to calibrate output impedance, then impedance matching is improved, but device complexity increases
Solution Approach 1:
The driver structure is segmented into multiple slices with independent enable/disable control. While this increases structural complexity, it enables precise impedance matching by selectively activating slices. The segmentation allows granular control over output impedance calibration.
Solution Approach 2:
Each driver slice is designed to be functionally identical and independently controllable, allowing the same hardware structure to serve multiple calibration points. This universality reduces the overall complexity compared to having completely different circuit structures for each calibration level.
Data Source
AI summary
A method of performing coarse calibration of a voltage-mode (VM) driver having a plurality of driver slices connected in parallel includes setting a control code applied to activated driver slices of the plurality of driver slices to a maximum value to minimize an output resistance of the activated driver slices, activating one driver slice of the plurality of driver slices by applying the control code to the one driver slice, while disabling other driver slices of the plurality of driver slices, measuring an output resistance of the VM driver, determining whether the output resistance of the VM driver is greater than a desired resistance, and in response to determining that the output resistance of the VM driver is greater than a desired resistance activating one more driver slice of the plurality of driver slices.