The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 21, 2002
Filed:
Jun. 15, 2000
Patrik Larsson, Matawan, NJ (US);
Agere Systems Guardian Corp., Orlando, FL (US);
Abstract
A frequency detector embodying the invention includes circuitry for comparing first (e.g., a reference) and second (e.g., a recovery clock) signals having first and second frequencies, respectively, and for producing an output signal having: (a) a first condition characterized as a “dead zone” when their frequency difference is within a predetermined frequency range; (b) a second condition when the frequency of the first signal is greater than that of the second signal by the predetermined range; and (c) a third condition when the frequency of the second signal is greater than that of the first by the predetermined range. Frequency detectors embodying the invention are suitable for use in frequency tuning systems. In one such system the output of a frequency detector is supplied to the input of a voltage controlled oscillator (VCO) for controlling the amplitude of the control voltage (Vc) applied to the VCO and the VCO output at which is produced the recovery clock signal (Ck) whose frequency is proportional to the amplitude of Vc. The frequency detector then functions to maintain the frequency of Ck within a predetermined frequency range. A system embodying the invention may also include a phase detector circuit responsive to the clock signal, Ck, and to a data input signal having a rate (ft) received from a transmitter for producing an output indicative of their phase difference, which output is also applied to the input of the VCO. In this embodiment the phase detector controls and locks the recovery clock signal to a frequency corresponding to the rate of the data input signals when the data rate is within the predetermined frequency range, without interference from the frequency detector.