Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!uwm.edu!rutgers!rochester!kodak!ornitz
From: ornitz@kodak.kodak.com (Barry Ornitz)
Newsgroups: sci.electronics
Subject: Re: 90 degree phase shift
Summary: Dome network
Keywords: phase shift
Message-ID: <1990Oct25.144535.15551@kodak.kodak.com>
Date: 25 Oct 90 14:45:35 GMT
References: <3899@osc.COM>
Sender: Barry L. Ornitz
Followup-To: sci.electronics
Organization: Eastman Kodak Co, Rochester, NY
Lines: 27

In article <3899@osc.COM> jgk@osc.COM (Joe Keane) writes:
>I have what seems to be a fairly simple problem.  I want to buld a circuit to
>phase shift an audio signal by 90 degrees.  I also want this to work over a
>range of frequencies and have fairly flat amplitude response.
>
>First, let me say what doesn't work.  
Joe then goes on with a discussion of several techniques he has investigated...

The networks that are used to produce a 90 degree phase shift over a limited
range of frequencies (which may be a number of decades) are nonminimum phase
networks.  The classic design is the Dome network used in many early phasing
single sideband exciters.  For references to this network, look in amateur
radio publications of the mid-1950's through the early 1960's.  Bill Orr's
"Radio Handbook" has a discussion of this, and surprizingly Horowitz and Hill's
"Art of Electronics" also discusses this network configuration.

					73, Barry  WA4VZQ

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|  ___  ________  |       Dr. Barry L. Ornitz          WA4VZQ
| |  / /        | |       Eastman Kodak Company
| | / /         | |       Eastman Chemical Company Research Laboratories
| |< < K O D A K| |       Process Instrumentation Research Laboratory
| | \ \         | |       P. O. Box 1972, Building 167B
| |__\ \________| |       Kingsport, TN  37662       615/229-4904
|                 |       INTERNET:   ornitz@kodak.com
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