Complementary Clock Distribution With Pin-Level Skew Correction
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Solution Overview
Problem
High-speed interface circuits face issues with clock signal skew and duty-cycle variations, leading to inefficiencies in data transmission and reception, and existing clock distribution circuits occupy significant area and consume high power.
Innovation Solution
The implementation of clock distribution circuits with adjustment circuits that reduce and eliminate skew and duty-cycle errors by using control logic to determine register values for fine or coarse adjustments, ensuring complementary clock signals with minimal phase differences, and incorporating output drivers to transmit and receive signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing clock distribution circuits are used, then clock signals can be distributed, but skew and duty-cycle variations occur leading to transmission errors
Solution Approach 1:
The patent implements feedback mechanisms where the clock distribution circuit monitors its own output signals for skew and duty-cycle errors, then automatically adjusts internal delay elements and buffer characteristics to compensate for detected variations, thereby maintaining high transmission reliability without external intervention
Solution Approach 2:
The circuit dynamically changes operational parameters such as buffer drive strength, delay line lengths, and signal routing paths based on detected clock signal characteristics, allowing adaptation to process variations and environmental changes to maintain precise clock distribution
2Area of stationary object
If existing clock distribution circuits are used, then clock signals can be distributed, but the circuits occupy large area and consume significant power
Solution Approach 1:
The patent divides the clock distribution function into multiple independent buffer stages and delay elements distributed throughout the circuit, allowing selective activation of only those segments needed for each specific clock route, thereby reducing overall power consumption and area usage compared to a monolithic distribution circuit
Solution Approach 2:
The circuit implements partial clock distribution by activating only the necessary buffer stages and delay elements for each receiver, rather than continuously driving all possible outputs, thus reducing power consumption while maintaining full functional capability when needed
3Speed
If complementary clock signals are used for high data rate communication, then transmission speed increases, but skew and duty-cycle variations cause errors
Solution Approach 1:
The patent employs asymmetric buffer designs where the rising and falling edge paths have different characteristics (different transistor sizes, different delay elements) to compensate for inherent asymmetries in the complementary clock generation process, thereby reducing duty-cycle errors while maintaining high-speed operation
Solution Approach 2:
The circuit performs preliminary adjustment of clock signal parameters through calibrated delay elements and buffer pre-conditioning stages before the signals reach the data transmission interface, ensuring that skew and duty-cycle errors are corrected in advance of the critical data sampling window
Data Source
AI summary
A circuit includes a clock generator to provide a clock signal, and a clock distribution circuit coupled to the clock generator and a plurality of pairs of outputs. The clock distribution circuit includes a plurality of adjustment circuits to generate a plurality of pairs of clock signals in accordance with the clock signal. A respective adjustment circuit in the plurality of adjustment circuits is to provide a respective pair of clock signals in the plurality of pairs of clock signals to a respective pair of outputs in the plurality of pairs of outputs. The respective pair of clock signals includes a first clock signal and a second clock signal. The first clock signal is a complement of the second clock signal and duty-cycle and skew errors in the first clock signal and the second clock signal are less than corresponding pre-determined values.