Date: Sat, 28 Jan 1995 09:44:33 -0800
Subject: Re: Substitute for 3080
From: Don Tillman <don@till.com>
Organization: Don's house, Palo Alto, California

   Date: Sat, 28 Jan 1995 18:02:46 +1100 (EDT)
   From: Damien James Miller <943127@edna.cc.swin.edu.au>

   I am currently in the process of designing a LPF/HPF/BPF/BRF filter, and I
   am wondering if there is any compelling reason not to use the 3080
   transconductance amp chips? Is there a dual model available? 

One very compelling reason: the 3080 has no noise spec.

The 3280 and LM13600/13700 are duals with great noise specs.

   also, can a Band reject (notch) filter be kludged by adding the inverted
   output of the bandpass filter with the input? is there a better way?

The best way is to sum the LP and HP outputs.  This gives you a notch
because of their relative phases.

   Date: Sat, 28 Jan 1995 00:02:07 -0800 (PST)
   From: Romeo Fahl <ms20@aa.net>

   Use the 3080.  Its imperfections are what make it great for electronic 
   music.   

Note that the linearizing circuitry in the other OTAs can be turned off.

   Date: Sat, 28 Jan 1995 12:31:02 +0100
   From: Rick Jansen <rick@SARA.NL>

   There's a 3280 too, a dual 3080. I don't know if you can really buy
   it though.

Digi-Key has'm for $4.18 (US) a piece and the LM13600A for $1.95.

  -- Don