Browse Prior Art Database

METHOD OF VCO TUNING WITH COAXIAL RESONATORS

IP.com Disclosure Number: IPCOM000006131D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2001-Dec-06
Document File: 1 page(s) / 50K

Publishing Venue

Motorola

Related People

Jose Suarez: AUTHOR

Abstract

A method of tuning voltage controlled oscillators by using ferrite loaded coaxial resonator is presented. The method offers advantages over the presently used method of capacitance trim.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 84% of the total text.

Page 1 of 1

0 M

MOTOROLA INC. Technical Developments Volume 12 April 1991

METHOD OF VCO TUNING WITH COAXIAL RESONATORS

by Jose Suarez

  A method of tuning voltage controlled oscillators by using ferrite loaded coaxial resonator is presented. The method offers advantages over the presently used method of capacitance trim.

REFERRING TO DIAGRAM IN FIGURE I

  Voltage controlled oscillators (VCOs) currently in use utilize coaxial resonators, with either circular or rectangular cross-sections; the way the oscillator is tuned for frequency, at a specified varactor voltage, consists of tuning a parallel plate capacitor, located at the resonator input, or some other convenient location in the tank circuit; this capacitor is implemented with essentially a short, wide open circuit line on the ceramic substrate, where the VCO circuit is built.

reducing VCO varactor sensitivity. An alternate approach, the subject of the present disclosure, is to tune the resonator itself; the resonator is a foreshortened line, and acts as an inductive impedance; tuning it results in an optimum procedure.

  The resonator is tuned, as shown in Figure I, by inserting a ferrite, off-center of resonator. By therefore tuning the effective inductance, a more sensitive and broadband frequency trim can be obtained.

  This results in a further advantage, namely reducing the number of different coaxial resonator lengths required to cover adjacent frequency bands. The typical resonator lengths range from 650 to 750

There ar...