Invention Grant
- Patent Title: System and method for an automatic coarse tuning of a voltage controlled oscillator in a phase-locked loop (PLL)
- Patent Title (中): 用于锁相环(PLL)中压控振荡器的自动粗调的系统和方法
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Application No.: US12006080Application Date: 2007-12-28
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Publication No.: US07808288B2Publication Date: 2010-10-05
- Inventor: Kallol Chatterjee
- Applicant: Kallol Chatterjee
- Applicant Address: IN Greater Noida
- Assignee: STMicroelectronics, Pvt. Ltd.
- Current Assignee: STMicroelectronics, Pvt. Ltd.
- Current Assignee Address: IN Greater Noida
- Agency: Graybeal Jackson LLP
- Agent Lisa K. Jorgenson; Kevin D. Jablonski
- Priority: IN2820/DEL/2006 20061228
- Main IPC: H03L7/06
- IPC: H03L7/06

Abstract:
Circuits and methods for an automatic coarse tuning in a phase locked loop (PLL) include observing a variation in a control voltage to disable a fine loop and to enable a coarse loop as the control voltage departs from a specified range. The circuit includes the fine loop, the coarse loop, and a control circuit. The fine loop includes a phase frequency detector (PFD), a charge pump, a loop filter, a VCO and a divider. The coarse loop includes a frequency detector, an up counter, a down counter, and an LC VCO. The control circuit includes a bandgap module, a comparator and other circuits such as a lock detect circuit. The control circuit is used to switch between the coarse loop and the fine loop.
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