Invention Grant
- Patent Title: Calibration method and apparatus for phase locked loop circuit
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Application No.: US15169997Application Date: 2016-06-01
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Publication No.: US09654121B1Publication Date: 2017-05-16
- Inventor: Min Chu
- Applicant: Integrated Device Technology, Inc.
- Applicant Address: US CA San Jose
- Assignee: INTEGRATED DEVICE TECHNOLOGY, INC.
- Current Assignee: INTEGRATED DEVICE TECHNOLOGY, INC.
- Current Assignee Address: US CA San Jose
- Agency: Glass & Associates
- Agent Kenneth Glass; William D. Davis
- Main IPC: H03L7/06
- IPC: H03L7/06 ; H03L7/099

Abstract:
An integrated circuit apparatus for calibrating a phase locked loop (PLL) circuit that includes a phase comparator configured to receive a reference clock signal and a feedback clock signal and generate a phase error signal, a variable frequency oscillator configured for receiving the phase error signal and generating a corresponding fast clock signal at an output of the variable frequency oscillator, and a divider that is configured to divide the fast clock signal by a divisor (N) so as to generate the feedback clock signal, includes a calibration circuit. The calibration circuit is coupled to receive the reference clock signal and the fast clock signal and to provide a frequency band selection signal to the variable frequency oscillator. The calibration circuit includes a counting circuit for counting a number of cycles of the fast clock signal over a period of time defined by a number of cycles (M) of the reference clock signal. The calibration circuit also includes a selection block for performing a convergence test using the counted number of fast clock cycles, N, and M. The selection block generates the frequency band selection signal in accordance with the results of the convergence test to select a next candidate calibrated frequency band.
Information query