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INTERNAL ISOLATION RINGS IMPROVE VCO PERFORMANCE

IP.com Disclosure Number: IPCOM000006528D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2002-Jan-11
Document File: 2 page(s) / 138K

Publishing Venue

Motorola

Related People

R. S. Kaltenecker: AUTHOR [+2]

Abstract

This publication describes a method that allows for the substantial size reduction of an electrical circuit with- out a degradation in the electrical performance of the circuit. Interactions (commonly referred to as "coupling effects") due to the close proximity of components, interconnections and signal traces often result in a reduc- tion of electrical performance parameters. With increas- ing emphasis on miniaturization along with higher operating frequencies this method provides a simple yet effective way to achieve the desired reduction in circuit size without sacrificing electrical performance.

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MOTOROLA INC. Technical Developments Volume 16

August 1992

INTERNAL ISOLATION RINGS IMPROVE VCO PERFORMANCE

by R. S. Kaltenecker and H. L. Wizenmayer

  This publication describes a method that allows for the substantial size reduction of an electrical circuit with- out a degradation in the electrical performance of the circuit. Interactions (commonly referred to as "coupling effects") due to the close proximity of components, interconnections and signal traces often result in a reduc- tion of electrical performance parameters. With increas- ing emphasis on miniaturization along with higher operating frequencies this method provides a simple yet effective way to achieve the desired reduction in circuit size without sacrificing electrical performance.

  The electrical circuit used to illustrate the technique is a VCO (voltage-controlled oscillator) module operat- ing at 2400 Mhz. The module consists of a VCO and a two stage buffer amplifier. The key electrical parameters of interest are the buffer reverse isolation and the result- ant VCO load pull (which is directly dependent on the amount of buffer reverse isolation).

  Figure 1 is a cross-sectional view of the VCO mod- ule with emphasis on the layering structure. The mod- ule consists of a multilayer printed circuit board (1) with surface mount components (2). The top metal layer (3) is for mounting the components while the inner layers
(4) are used for the buffer amplifier matching networks, bias networks and the VCO tank circuit. The transmis- sion lines used for these functions are implemented in stripline construction. A stripline (transmission line) con- sists of a center conductor (5) enclosed in a dielectric material (6) between two ground planes (7).

  Multilayer printed circuit boards are ideally suited for the construction of a transmission lie in stripline fashion, additionally they provide...