Clock Duty Compensation Using Asynchronous Multi-Period Sampling
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Solution Overview
Problem
Conventional duty compensation devices often inaccurately measure the duty of a clock, leading to the output clock not being within the appropriate range, causing malfunctions such as even/odd jitter in serializer devices.
Innovation Solution
A duty compensation device comprising a duty adjusting unit, a duty measuring unit, and a controlling unit, where the duty measuring unit generates an asynchronous sampling clock to accurately measure the duty of the clock, and the controlling unit determines a control code to adjust the duty within a predetermined range by selecting a median or non-extreme control code candidate based on measurement information from multiple periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a synchronous sampling clock is used to measure duty, then the measurement process is simple, but the measurement value significantly differs from the actual duty value
Solution Approach 1:
The patent changes the fundamental parameter of the sampling clock from synchronous to asynchronous relative to the measurement target clock. This parameter change allows the sampling clock to capture the actual duty cycle values without being constrained by phase relationships, thereby achieving accurate measurement while maintaining relatively simple circuit complexity.
2Loss of time
If a single period measurement is performed, then the measurement process is fast, but the duty may not be within the appropriate range
Solution Approach 1:
The patent employs periodic measurement actions across multiple clock periods (N≥3) to gather sufficient data for reliable duty determination. By performing measurements over multiple periods and selecting appropriate control codes based on this aggregated data, the system ensures that the final duty value falls within the appropriate range while maintaining efficient operation.
Solution Approach 2:
The patent implements a feedback mechanism where measurement results from multiple periods are fed back to the control unit. The control unit then determines optimal control codes based on this feedback, ensuring that the duty-adjusted clock output maintains the appropriate duty range. This closed-loop feedback ensures reliability without requiring excessively long measurement times.
3Speed
If extreme control code candidates are selected, then the adjustment response is quick, but the duty may exceed the predetermined range
Solution Approach 1:
The patent measures over N periods (where N≥3) which is more than the minimum single period, but not excessively so. This partial excess measurement provides sufficient data to reliably determine control codes that keep duty within the predetermined range, balancing measurement speed with precision requirements.
Solution Approach 2:
The patent changes the selection criterion for control codes from extreme values to median or non-extreme values based on measurements from multiple periods. This parameter change in selection strategy ensures that the chosen control code produces duty values within the appropriate range while maintaining reasonably fast adjustment response.
Data Source
AI summary
A duty compensation device of one embodiment has a structure capable of more accurately setting a duty of a clock within an appropriate range. The duty compensation device comprises a duty adjusting unit, a duty measuring unit, a controlling unit. The duty measuring unit generates a sampling clock of a frequency fn that is asynchronous to the clock over an n-th period Tn (n=1 to N and N is an integer of 3 or more), and obtains measurement information for specifying the duty of the clock by using the sampling clock. The controlling unit determines a control code to be given to the duty adjusting unit based on control code candidates obtained for each of the N periods T1 to TN and the control code candidates in which the duty specified by measurement information obtained by the duty measuring unit is within a predetermined range.