Clock generation and correction circuit

Abstract

A clock generation and correction (CGC) circuit comprises a clock and data recovery (CDR) circuit, a start-of-frame (SOF) detector circuit, a counter, a digital logic circuit, a fractional-N phase locked loop (PLL), and an oscillator circuit. The CDR receives an input data signal and an internal clock signal and generates a recovered data signal. The SOF detector circuit generates a toggle signal based on a comparison of the recovered data signal to a predetermined data signal pattern. The counter generates a clock cycle count signal based on the toggle signal. The digital logic circuit generates a frequency adjustment signal based on an error in the frequency of the clock signal. The oscillator circuit generates an intermediate clock signal. The fractional-N PLL circuit receives the frequency adjustment signal and the intermediate clock signal and modifies the internal clock signal based on the frequency adjustment signal.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the right of priority based on India Provisional Application Serial No. 201941042608, entitled “Clock Generation And Correction Circuit”, filed Oct. 21, 2019, which is incorporated by reference in its entirety.BACKGROUND1. Field of Art[0002]The present disclosure relates generally to communication systems, and more specifically, to clock generation and correction (CGC) circuits.2. Description of the Related Art[0003]Data communication systems are constantly adapted to serve the ever-increasing need for high speed data communication. Data communication systems require highly accurate clocks to coordinate actions of the system. Clocks provide a type of signal (e.g., a clock signal) that oscillates between a high state and a low state. Clock signals are generated by oscillators. Currently, on-chip oscillators (e.g., a resistor-capacitor (RC) oscillator) and external crystal oscillators may be used to create an electri...

AI Technical Summary

Benefits of technology

The CGC circuit achieves accurate local clock signal generation with an accuracy of ±2,500 parts per million or higher, correcting the frequency as needed, thereby enhancing data transmission accuracy without the need for external oscillators, reducing costs, and optimizing chip area.

Problems solved by technology

However, the on-chip oscillators provide poor frequency stability and the external crystal oscillators consume additional area on the chip, which increases cost of the device.

However, the RC oscillator provides poor frequency stability in the generation of the local clock signal, thus affecting the desired accuracy.

However, as explained above, using an external oscillator component with the oscillator circuit increases the overall cost of the USB device and consumes additional area on the chip.

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