LC quadrature VCO having startup circuit

Details LC quadrature VCO having startup circuit LC quadrature VCO having startup circuit

2006-12-22

2008-10-14

Chang, Joseph (Department: 2817)

Oscillators

Solid state active element oscillator

Transistors

C331S045000, C331S046000

Reexamination Certificate

active

07436266

ABSTRACT:
Provided is an Inductor-Capacitor (LC) quadrature Voltage Controlled Oscillator (VCO) having a startup circuit which can accurately select one of +90° and −90° as a phase difference between two clocks generated by the LC quadrature VCO by embodying the startup circuit therein by using a phase detector and a controller. The LC quadrature VCO includes a first LC tank for generating a second clock signal and a fourth clock signal, a second LC tank for generating a first clock signal and a third clock signal, a phase detector for receiving the clock signals from the first LC tank and the second LC tank, and detecting whether a phase difference between the clocks is +90° or −90°, and a controller for discriminating whether phase information detected by the phase detector is equivalent to a phase difference between clocks required by the external signal processing unit, and changing an operation mode of the first LC tank and/or the second LC tank on the basis of the discrimination result of the phase difference between the clocks.

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Li, Shenggao, et al., “A 10-GHz CMOS Quadrature LC-VCO for Multirate Optical Applications”, Oct. 2003,IEEE Journal of Solid-State Circuits, vol. 38, No. 10.
Notice of Korean Patent Grant dated Oct. 26, 2007 for the corresponding application KR 10-2006-0095677.

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