Oscillators – Automatic frequency stabilization using a phase or frequency... – With reference oscillator or source
Reexamination Certificate
1999-05-03
2001-02-13
Mis, David (Department: 2817)
Oscillators
Automatic frequency stabilization using a phase or frequency...
With reference oscillator or source
C331S016000, C331S025000, C331S158000, C331S179000, C327S156000, C327S159000
Reexamination Certificate
active
06188290
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to programmable crystal oscillators. In particular, the present invention is directed toward a programmable crystal oscillator having an adjustable capacitive load circuit coupled to the crystal.
Crystal oscillators are widely used to generate timing signals for electronic hardware, such as computers, instrumentation, and telecommunications equipment. Crystal oscillators typically include a quartz crystal and an oscillator circuit, which electrically excites the crystal so as to generate an oscillating signal at a resonant frequency determined by physical characteristics of the crystal. The oscillator circuit or a separate output circuit (buffer) wave-shapes the oscillating signal into a timing pulse train acceptable to the electronic hardware.
Timing frequencies are specified by the electronic hardware manufacturers and thus vary over a wide frequency range. However, a crystal's resonant frequency is determined by its physical characteristics, e.g., size, shape, crystalline structure, etc. Trimming the crystal's resonant frequency can be achieved by selective metal plating the crystal faces. Consequently, the manufacture of crystal oscillators is an involved process that is both time consuming and costly. Thus, suppliers of crystal oscillators stock large numbers of crystal oscillators manufactured to a variety of standard output frequencies. However, if a customer requires a custom frequency, a manufacturer generally must “start from scratch” by dicing an ingot into crystal wafers of specific dimensions and then subjecting the crystal wafers to numerous processing steps (lapping, etching, and plating), all designed to achieve the custom output frequency. Custom crystal oscillators come at premium prices and require long manufacturing leadtimes (months).
Since virtually all crystals are capable of oscillating, manufacturing yield is quite high. However, if the crystal's resonant frequency cannot be trimmed to meet one customer's frequency specification, the crystals are typically inventoried in the hope that they can be used to meet another customer's frequency specification. In the case of custom crystal oscillators, it is not uncommon for manufacturers to produce an oversupply of custom crystals to ensure a sufficient volume of crystals capable of meeting customer requirements in terms of both output frequency and quantity. The excess crystal oscillators are then placed in inventory. Maintaining large crystal inventories represents a significant manufacturing expense.
SUMMARY OF THE INVENTION
Systems and methods consistent with this invention resolve certain disadvantages of conventional approaches by providing a timing circuit comprising a crystal for generating a source frequency, an oscillator circuit coupled to the crystal, and a programmable load circuit coupled to the crystal. A frequency multiplier circuit is coupled to the oscillator circuit to receive the adjusted source frequency. Further, a programming circuit is included to supply first programming data to the programmable load circuit to adjust the crystal source frequency and second programming data to the frequency multiplier circuit. The frequency multiplier circuit, in turn, supplies an output frequency equal to a product of the adjusted source frequency and a multiplication factor designated by the second programming data.
Advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Additionally, advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
REFERENCES:
patent: 2964714 (1960-12-01), Jakubowics
patent: 3916307 (1975-10-01), Hekimian
patent: 4020425 (1977-04-01), Hoffmann et al.
patent: 4320357 (1982-03-01), Wulfsberg et al.
patent: 4343219 (1982-08-01), Urtrecht
patent: 4459566 (1984-07-01), Lane
patent: 4468636 (1984-08-01), Monticelli
patent: 4486846 (1984-12-01), McCallister et al.
patent: 4590941 (1986-05-01), Saulson et al.
patent: 4689581 (1987-08-01), Talbot
patent: 4835491 (1989-05-01), Coster
patent: 4984155 (1991-01-01), Geier et al.
patent: 5053723 (1991-10-01), Schemmel
patent: 5063358 (1991-11-01), Vale et al.
patent: 5142247 (1992-08-01), Lada, Jr. et al.
patent: 5150079 (1992-09-01), Williams et al.
patent: 5216595 (1993-06-01), Protheroe
patent: 5262735 (1993-11-01), Hashimoto et al.
patent: 5302920 (1994-04-01), Bitting
patent: 5323125 (1994-06-01), Hiben et al.
patent: 5349544 (1994-09-01), Wright et al.
patent: 5446420 (1995-08-01), Westwick
patent: 5451912 (1995-09-01), Torode
patent: 5457433 (1995-10-01), Westwick
patent: 5465076 (1995-11-01), Yamauchi et al.
patent: 5467373 (1995-11-01), Ketterling
patent: 5548252 (1996-08-01), Watanabe et al.
patent: 5563554 (1996-10-01), Mizuno
patent: 5570066 (1996-10-01), Eberhardt et al.
patent: 5579231 (1996-11-01), Sudou et al.
patent: 5636346 (1997-06-01), Saxe
patent: 5668506 (1997-09-01), Watanabe et al.
patent: 5940457 (1999-08-01), Dreifuss et al.
patent: 5952890 (1999-09-01), Fallisgaard et al.
patent: 0 053 561 A2 (1982-06-01), None
patent: 0 203 756 (1986-12-01), None
patent: 0 437 634 A1 (1991-07-01), None
patent: 0 637 876 (1995-02-01), None
patent: 1335142 (1973-10-01), None
patent: 2 282 500 (1995-04-01), None
patent: 2-291161 (1990-11-01), None
patent: 3-297223 (1991-12-01), None
D. Soderquist, “Digitally programmed oscillator is suitable for &mgr;P control”,Electronic Design 13, Jun. 21, 1997, pp. 103-104.
A. Foord, “Voltage Controlled oscillator,”Radio and Electronics constructor, vol. 28, No. 10, pp. 590-595, May 1975.
T.G. Giles, “A universal frequency synthesizer IC,”Phillips Telecommunication Review, vol. 37, No. 3, Aug. 1979, pp. 177-181.
Cypress Semiconductor Marketing Brochure, Published Nov., 1993, pp. 5-7, a publication of Cypress Semiconductor, San Jose, California.
W. Ooms, Improved Frequency Synthesizer,Motorola Technical Disclosure Bulletin, vol. 6, No. 1, pp. 4-6, Oct. 1, 1986, Schaumbourg, Illinois, USA.
E. Mielke, Programmierbarer 50 MHz-Muttertaktimpulsegenerator,:Radio Fernsehen Elektronik, vol. 39, No. 9, pp. 560-563, Jan. 1, 1990, Berlin, Germany.
IC Designs, “Satellite Oscillator,” Model number ICD2031A, May 1991.
IC Designs, “Programmable Clock Oscillator,” Model number ICD2053A.
IC Designs, “Frequency Multiplier,” Model number ICD2032, May 1991.
“ICD6233 Characterization Data,” 1994.
IC Designs, “Dual Programmable Clock Oscillator,” Model number ICD2051, May 1991.
MF Electronics Corp., “Phase Locked VCXO 10 MHz to 32.768 MHz,” 1994.
MF Electronics Corp., “20 to 200 MHz Programmable ECL,” 1994.
M-Tron, “MV Series VCXO Oscillators,” 1994.
M-Tron, “MV Series VCXO Oscillators,” 1995.
Vectron Labs., “Sonet Clock Recovery Module SCRM-622,” Nov. 94.
Wenzel Associates Inc., “Custom Oscillator Configurations.”.
Connor-Winfield Corp., “SM PECL PLL Frequency Multiplier,” 1995.
Epson, “Programmable Multi-Output Crystal Oscillator MG-5010,” Mar. 7, 1993.
M-Tron, “MT1135 Series Dual Baud Rate Generators,” 1987.
Hybrids International, Ltd., “Voltage Controlled Crystal Oscillators,” pp. VCX-1 to VCX-3, 1995.
National Semiconductor, “IMX2306/2316/2326 PLLatinum Low Power Frequency Synthesizer for RF Personal Communications,” Jan. 1998.
Hybrids International, Ltd., “Frequency Products,” Sep. 23, 1994.
MF Electronics Corp., “Voltage Controlled Oscillators 1 MHz to 175 MHz,” 1994.
Hybrids International, Ltd., “Product Summary,” Aug. 1993.
Hybrids International, Ltd., “Crystal Oscillators: Voltage Controlled,”
Fallisgaard John W.
Trefethen Eugene S.
Finnegan Henderson Farabow Garrett and Dunner, LLP
Fox Enterprises, Inc.
Mis David
LandOfFree
Method of initializing an oscillator circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of initializing an oscillator circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of initializing an oscillator circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2603844