Title: Compensated-clock generating circuit and usb device having same
Application Number: 200610159543 Application Date: 2006.09.27
Publication Number: 1940808 Publication Date: 2007.04.04
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: G06F1/04;H03L7/00;H03K3/023
Applicant(s) Name: NEC Electronics Corp. Address:
Inventor(s) Name:
Attorney & Agent: lujin hua xieli na
Abstract:
    A compensated-clock generating circuit that complies with USB specifications includes an oscillating circuit that generates clock pulses; a counting circuit that counts the number of clock pulses from the oscillating circuit based upon a regular prescribed signal in accordance with a USB downstream signal; and a frequency compensation value generating circuit that compares the value counted by the counting circuit and a prescribed reference value and obtaining a compensation value. The oscillation frequency of the oscillating circuit is corrected to a prescribed value in response to receipt of the compensation value from the frequency compensation value generating circuit. Compensation is applied based upon a highly accurate signal that is based upon USB specifications, thereby making it possible to generate pulses of higher accuracy even if the accuracy of the oscillation frequency per se of the oscillator in the oscillation circuit is low.
Time: 10
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