Invention Grant
US08344812B2 Loop filter and voltage controlled oscillator for a phase-locked loop
有权
用于锁相环的环路滤波器和压控振荡器
- Patent Title: Loop filter and voltage controlled oscillator for a phase-locked loop
- Patent Title (中): 用于锁相环的环路滤波器和压控振荡器
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Application No.: US13028340Application Date: 2011-02-16
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Publication No.: US08344812B2Publication Date: 2013-01-01
- Inventor: Krishnaswamy Nagaraj , Ajay Kumar , Xiao Pu , Sreekiran Samala
- Applicant: Krishnaswamy Nagaraj , Ajay Kumar , Xiao Pu , Sreekiran Samala
- Applicant Address: US TX Dallas
- Assignee: Texas Instruments Incorporated
- Current Assignee: Texas Instruments Incorporated
- Current Assignee Address: US TX Dallas
- Agent Ronald O. Neerings; Wade James Brady, III; Frederick J. Telecky, Jr.
- Main IPC: H03L7/00
- IPC: H03L7/00

Abstract:
A phase-locked loop includes a loop filter and a voltage controlled oscillator (VCO). The VCO includes multiple transistors, each transistor having a smaller transconductance (gm) than if a single transistor were used while maintaining the same loop bandwidth and drain-to-source current through the transistor. As a result of a smaller transconductance in the VCO, a larger resistor can be used in the loop filter without increasing the noise. With a larger resistor, a smaller capacitor can be used in the loop filter as well. Alternatively, the transconductance can be reduced by a certain factor and the resistance value can be increased by the same factor to maintain a constant loop bandwidth but with a reduction in the amplitude of the noise. Thus, a smaller loop filter capacitor can be achieved albeit with the same noise level, or a lower noise level with the same size capacitor for the loop filter.
Public/Granted literature
- US20110199137A1 LOOP FILTER AND VOLTAGE CONTROLLED OSCILLATOR FOR A PHASE-LOCKED LOOP Public/Granted day:2011-08-18
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