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:
Jan. 11, 2011
Filed:
Feb. 04, 2009
Shayan Farahvash, Cupertino, CA (US);
Chee Kwang Quek, Sunnyvale, CA (US);
Monica Mak, Sunnyvale, CA (US);
Shayan Farahvash, Cupertino, CA (US);
Chee Kwang Quek, Sunnyvale, CA (US);
Monica Mak, Sunnyvale, CA (US);
RF Micro Devices, Inc., Greensboro, NC (US);
Abstract
The present invention relates to a digitally-controlled crystal oscillator (DCXO) circuit having control circuitry, an active core, and a pair of thermometer-coded switched-capacitor circuits (TCSCCs), each of which is coupled to the active core and to a crystal. The active core, the crystal, and the pair of TCSCCs form a DCXO, which provides an output signal having an output frequency. Each TCSCC includes multiple capacitive elements, which are selected by a respective control signal from the control circuitry to control the output frequency. The DCXO circuit may be integrated into a digital integrated circuit (IC) without need for a digital-to-analog converter (DAC), and may be used with a wide range of crystal types. By using thermometer-coding, the pair of TCSCCs provides monotonic frequency tuning behavior. Further, by utilizing different types of tuning steps, the DCXO may have a wide tuning range with high resolution.