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:
Apr. 05, 2005
Filed:
Apr. 21, 2003
Linley F. Gumm, Beaverton, OR (US);
Linley F. Gumm, Beaverton, OR (US);
Tektronix, Inc., Beaverton, OR (US);
Abstract
A phase lock for a synthesizer phase reference oscillator that is used in conjunction with a conventional DDS circuit to synthesize an RF output frequency includes a second DDS circuit that is added with a reference increment value as an input to provide a phase offset frequency. A frequency/phase comparator compares a frequency reference oscillator output with the phase offset frequency to generate a control signal for phase locking the phase reference oscillator to the frequency reference oscillator. To determine the correct value for the reference increment value, a switch is provided between the frequency/phase comparator and the phase reference oscillator and the control signal is input to an analog-to-digital converter. During a 'turn on' procedure the resulting digitized control signal is observed by a control system as the reference increment value is adjusted until a slow ramp, positive or negative, in the control signal is observed. Then the switch is closed to allow the control signal to phase lock the phase reference oscillator coherently to the frequency reference oscillator. In this way coherence is achieved from unit to unit with a more precise frequency output.