Browse Prior Art Database

BALANCED VCO WITH RING RESONATOR

IP.com Disclosure Number: IPCOM000006209D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2001-Dec-13
Document File: 1 page(s) / 51K

Publishing Venue

Motorola

Related People

Jose Suarez: AUTHOR

Abstract

An Oscillator VCO with a ring resonator for the UHF band is shown which allows low voltage opera- tion with good sideband noise.

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MOmROLA INC. Technical Developments Volume 13 July 1991

BALANCED VCO WITH RING RESONATOR

by Jose Suarez

  An Oscillator VCO with a ring resonator for the UHF band is shown which allows low voltage opera- tion with good sideband noise.

  Voltage controlled oscillators (VCOs) currently in use utilize coaxial resonators grounded on one end and having only one oscillating active device. For low voltage operation, in the five volt or less range, the dynamic range for the device is constricted. Also, it is difficult to obtain good sideband noise performance primarily due to the ensuing low efficiency of the oscillator in converting DC power to tank RF power.

  The circuit depicted in the figure solves the prob- lem by doubling up on the devices and floating the resonator, which is implemented with a ring resonator with a virtual RF ground in the center; efficiencies of

up to 25% have been obtained. The circuit is made by creating a b&snced structure out of a single device oscillator; capacitors Cl1 and Cl2 for the common mode second harmonic are grounded providing low impedance, while for the odd mode fundamental appear as a capacitor of half the value; this is impor- tant to ensure better limiting characteristics and more power. The output is converted to single ended with a transmission line, although for some applications it is desirable to keep the balanced nature of the signal.

Other advantages include reduced even harmonics

on the output and on th,e devices. In addit...