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Title: US6882229: Divide-by-X.5 circuit with frequency doubler and differential oscillator
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Country: US United States of America

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13 pages

 
Inventor: Ho, Jeff; Hong Kong, China
Wing, Choy Kwok; Hong Kong, China

Assignee: Pericom Semiconductor Corp., San Jose, CA, United States of America
other patents from PERICOM SEMICONDUCTOR CORP. (713978) (approx. 58)
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Published / Filed: 2005-04-19 / 2003-07-23

Application Number: US2003000604461

IPC Code: Advanced: H03K 23/50; H03K 23/68; H03L 7/00; H03L 7/099; H03L 7/18;
Core: H03K 23/00; H03L 7/08; H03L 7/16; more...
IPC-7: H03L 7/00;

ECLA Code: H03L7/099C; H03K23/50B; H03K23/68; H03L7/18;

U.S. Class: 331/001.A; 331/045; 327/156; 327/158;

Field of Search: 331/1 A,45 327/156,158,160,161

Priority Number:
2003-07-23  US2003000604461

Abstract:     A divide by X.5 circuit can be implemented as a divided by 1.5 circuit. A phase-locked loop (PLL) has a quadrature voltage-controlled oscillator (VCO) that generates four phases offset at 0, 90, 180, and 270 degrees. Differential signals from the VCO are converted to single-ended VCO clocks that drive four divide-by-3 circuits, each clocked by one of the four phases of the VCO clocks. Resets to the divide-by-3 circuits are staggered to activate each divide-by-3 circuit synchronously with its phase clock. Outputs from the divide-by-3 circuits are applied to a frequency doubler that generates the final clock that is 1.5 times slower than the VCO clocks. The final clock has a near 50%-50% duty cycle.

Attorney, Agent or Firm: Auvinen, Stuart T. ;

Primary / Asst. Examiners: Shingleton, Michael B;

INPADOC Legal Status: Show legal status actions

Family: None

First Claim:
Show all 20 claims
    1. A divide-by-X.5 circuit, wherein X is a whole number, comprising:

a phase-locked loop having a voltage-controlled oscillator (VCO) that generates four phase clocks having a same input frequency but having differing phase offsets;

a first divide-by-X-plus-two circuit, receiving a first phase clock of the four phase clocks, for generating a first divided-by-X-plus-two signal that has a frequency being the input frequency divided by (X+2), the first divided-by-X-plus-two signal being synchronous to the first phase clock;

a second divide-by-X-plus-two circuit, wherein X-plus-two is twice X, receiving a second phase clock of the four phase clocks, for generating a second divided-by-X-plus-two signal that has a frequency being the input frequency divided by (X+2), the second divided-by-X-plus-two signal being synchronous to the second phase clock;

a third divide-by-X-plus-two circuit, wherein X-plus-two is twice X, receiving a third phase clock of the four phase clocks, for generating a third divided-by-X-plus-two signal that has a frequency being the input frequency divided by (X+2), the third divided-by-X-plus-two signal being synchronous to the third phase clock;

a fourth divide-by-X-plus-two circuit, wherein X-plus-two is twice X, receiving a fourth phase clock of the four phase clocks, for generating a fourth divided-by-X-plus-two signal that has a frequency being the input frequency divided by (X+2), the fourth divided-by-X-plus-two signal being synchronous to the fourth phase clock; and

a frequency doubler, receiving the first, second, third, and fourth divided-by-X-plus-two signals, for generating an output clock having an output frequency that is the input frequency divided by X.5,

whereby the output clock is generated from the four phase clocks from the voltage-controlled oscillator.



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Forward References: Show 2 U.S. patent(s) that reference this one

       
U.S. References: Go to Result Set: All U.S. references   |  Forward references (2)   |   Backward references (16)   |   Citation Link

Buy
PDF
Patent  Pub.Date  Inventor Assignee   Title
Buy PDF- 10pp US3930169  1975-12 Kuhn  Motorola, Inc. Cmos odd multiple repetition rate divider circuit
Buy PDF- 7pp US4041403  1977-08 Chiapparoli, Jr.  Bell Telephone Laboratories, Incorporated Divide-by-N/2 frequency division arrangement
Buy PDF- 4pp US4348640  1982-09 Clendening  Rockwell International Corporation Divide by three clock divider with symmertical output
Buy PDF- 11pp US4354188  1982-10 Schneider  U.S. Philips Corporation Device for dividing a recurrent input signal by a non-integer divisor f, notably by f=N-1/2
Buy PDF- 11pp US4587664  1986-05 Iida  NEC Corporation High speed frequency divider dividing pulse by a number obtained by dividing an odd number by two
Buy PDF- 8pp US4590439  1986-05 Goggin  E-Systems, Inc. Frequency synthesizing circuit
Buy PDF- 10pp US4606059  1986-08 Oida  Tokyo Shibaura Denki Kabushiki Kaisha Variable frequency divider
Buy PDF- 6pp US4866741  1989-09 Minuhin  Magnetic Peripherals Inc. 3/2 Frequency divider
Buy PDF- 12pp US4935944  1990-06 Everett  Motorola, Inc. Frequency divider circuit with integer and non-integer divisors
Buy PDF- 6pp US4942595  1990-07 Baca  AG Communication Systems Corporation Circuit for dividing the frequency of a digital clock signal by two and one-half
Buy PDF- 19pp US5339345  1994-08 Mote  AST Research Inc. Frequency divider circuit
Buy PDF- 9pp US5442670  1995-08 Shu  National Semiconductor Corporation Circuit for dividing clock frequency by N.5 where N is an integer
Buy PDF- 5pp US5457722  1995-10 Chahabadi  Blaupunkt-Werke GmbH Circuit for frequency division by an odd number
Buy PDF- 12pp US6356123  2002-03 Lee et al.  Via Technologies, Inc. Non-integer frequency divider
Buy PDF- 8pp US6389095  2002-05 Sun  Qualcomm, Incorporated Divide-by-three circuit
Buy PDF- 22pp US6445760  2002-09 Weintraub et al.  Applied Micro Circuits Corporation Partially-synchronous high-speed counter circuits
       
Foreign References: None

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