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NARROW BAND TO BROADBAND 90 AND 180 DEGREES TRANSLATION ARCHITECTURES

IP.com Disclosure Number: IPCOM000009472D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-27
Document File: 2 page(s) / 115K

Publishing Venue

Motorola

Related People

Richard M. Dougherty: AUTHOR

Abstract

During the last several years the necessity for improved synthesizer performance has become increasingly acute. In order to improve perfor- mance, designers have investigated the use of adap- tive architectures to improve phase noise perfor- mance, settling time and spurious generation. In view of this, synthesizer architectures have evolved into muti-loop designs depending upon mixers for signal insertion and frequency control. In support of the foregoing, circuit techniques employing Single Side Band Generator (SSBG) have been adopted by synthesizer architectures to enhance spurious perfor- mance. The primary attribute for improving spuri- ous performance using this vehicle is the SSBG ability to select either upper or lower sidebands to circumvent in band spurious products. The prob- lems normally encountered regarding the aforemen- tioned are; complex circuit topologies, limited band- width and increased cost / circuit size.

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Developments Technical 0 M MOloRolA

NARROW BAND TO BROADBAND - 90 AND 180 DEGREES

TRANSLATION ARCHITECTURES

by Richard M. Dougherty

  l During the last several years the necessity for improved synthesizer performance has become increasingly acute. In order to improve perfor- mance, designers have investigated the use of adap- tive architectures to improve phase noise perfor- mance, settling time and spurious generation. In view of this, synthesizer architectures have evolved into muti-loop designs depending upon mixers for signal insertion and frequency control. In support of the foregoing, circuit techniques employing Single Side Band Generator (SSBG) have been adopted by synthesizer architectures to enhance spurious perfor- mance. The primary attribute for improving spuri- ous performance using this vehicle is the SSBG ability to select either upper or lower sidebands to circumvent in band spurious products. The prob- lems normally encountered regarding the aforemen- tioned are; complex circuit topologies, limited band- width and increased cost / circuit size.

  In light of the above. The following outlines a circuit technique, which resolves the complexity, associated with the formulation of a broadband 90 degree network needed for operation by Single Side Band Generator.

  The need for low cost high performance broad- band I and Q networks for the operation of Single Side Band Generators (SSBG) applications has become a concern receiving renewed focus with the advent of improved spurious requirements. In addi- tion, focus toward reduced size I cost requires an architecture which can be readily supported by pre- sent day ASIC technologies (BICMOS, GCMOS, GaAs . ..etc). The thrust of this circuit architecture was to formulate a broadband I and Q (go-degree network) structure which would readily address or transcend the following:

   Reduce the requirement for large expensive broadband go-degree hybrids employing ferrite technology.

  l Exhibit excellent phase / amplitude balance over several decades

l Architectures supporting ASIC capabilities

  l Eliminate the need for digital broadband I and Q architectures which require frequencies at twice the required and effectuate output signals large in harmonic content

  l Overcome the operational bandwidth limita- tion (one octave) of polyphase RC lattice I and Q networks.

  The principle techniques employed to achieve the aforementioned were:

  1. Utilize a simple RC network to gen...