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 Title: |
US7015766:
CMOS voltage-controlled oscillator (VCO) with a current-adaptive resistor for improved linearity
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Guo, Zhangqi; San Jose, CA, United States of America
Zhang, Michael Y.; Palo Alto, CA, United States of America
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| 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: |
2006-03-21
/ 2004-07-27
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| Application Number: |
US2004000710657
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| IPC Code: |
Advanced:
H03B 5/04;
H03B 5/24;
Core:
H03B 5/00;
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| ECLA Code: |
H03K5/13D2; H03L7/099C;
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| U.S. Class: |
331/176;
331/057;
331/185;
331/186;
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| Field of Search: |
331/008,17,57,177 R,175,176,185,186
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| Priority Number: |
| 2004-07-27 |
US2004000710657 |
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| Abstract: |
A voltage-controlled oscillator (VCO) for a phase-locked loop (PLL) has improved bandwidth and performance at lower frequency. A variable current source supplies a current to an internal oscillator-power node. The current varies with the VCO input voltage. The internal oscillator-power node drives the sources of p-channel transistors in inverter stages in the ring oscillator. The variable current causes the internal oscillator-power node's voltage to vary, which varies the output frequency. An active resistor is in parallel with the ring oscillator. The active resistor has a resistor and an n-channel transistor in series between the oscillator-power node and ground. The n-channel transistor has a fixed bias voltage on its gate and is non-linear. The non-linear effective resistance of the n-channel transistor improves overall linearity of the ring oscillator. The parallel effective resistance of the active resistor lowers overall effective resistance of the ring oscillator. Oscillator bandwidth at lower frequencies improves.
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| Attorney, Agent or Firm: |
Auvinen, Stuart T. ;
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| Primary / Asst. Examiners: |
Mis, David;
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| INPADOC Legal Status: |
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| Family: |
None
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First Claim:
Show all 20 claims |
1. A voltage-controlled oscillator (VCO) comprising: an output clock having an output frequency; an input having an input voltage that is varied to vary output frequency; a variable current source, responsive to the input, for varying a current to a source node in response to the input voltage; a ring oscillator that generates the output clock, the ring oscillator having the source node supplying current to transistors in the ring oscillator wherein varying a source voltage of the source node varies the output frequency of the output clock generated by the ring oscillator; a bypass capacitor coupled to the source node; and an active resistor coupled in parallel with the ring oscillator to the source node, the active resistor having a series resistor and a series transistor in series, whereby the active resistor in parallel with the ring oscillator lowers an R-C time constant of the source node.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 2 U.S. patent(s) that reference this one
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