[sdiy] Replacing CA3080 with CA3046 ??

[karl dalen]

The bergfotron test are incomplete, it lacks a cv bleedtrough plot 
as the Iabc are varying over the range used.

Second, in the case of 13600 depending on the Iabc source
wheter its a simple resistor or a PNP stage the varying 
impedance affects the bleedtrough! Im not 100% sure on this
i might be 100% wrong but something strange there is!!

Reg
KD

--- Tim Parkhurst <tparkhurst at siliconbandwidth.com> wrote:
>  Seems like a discrete transistor OTA might not be the best (or easiest) VCA
> solution. Check out Jorgen's VCA comparison at
> 
> http://www.idg.se/personal/bergfors/bergfotron/VCA.htm
> 
> This comparison shows that actually the lowly 13600 makes a pretty darn good
> VCA. This list includes the 3080 , the SSM2024, 3046 and 3086-based OTAs,
> amongst others. It doesn't include the 3280 or 5517 however. 
> 
> 
> Tim (pretty good by comparison) Servo
> 
> *******************************
> -----Original Message-----
> From: srnovak at ncsu.edu
> To: synth-diy at dropmix.xs4all.nl
> Sent: 4/8/05 11:14 PM
> Subject: Re: [sdiy] Replacing CA3080 with CA3046 ??
> 
> Another thought in comparing MAT04 with CA3046 is that each chip was
> designed for it's technology (i.e. junction isolation Vs. trench
> isolation). The Collector-Emitter breakdown voltage of the MAT04 is 40V,
> where the Colector-Substrate breakdown voltage of the CA3046 is 20V min
> and typical is 60V. I was planning on running off single 12V, but even
> with a dual 12V supply, it seems both chips would be in no danger of
> parisitic diodes or BJT's as long as the substrate was at the lowest
> voltage (also assuming I have a little better then the worse CA3046).
> 
> 	From: 	  patchell at cox.net
> 	Subject: 	Re: [sdiy] Replacing CA3080 with CA3046 ??
> 	Date: 	April 8, 2005 11:12:09 PM EDT
> 	To: 	  samppa.tolvanen at gmail.com, madhun2001 at yahoo.com
> 	Cc: 	  srnovak at ncsu.edu, synth-diy at dropmix.xs4all.nl
> 
> The MAT04 is dialectically isolated (the CA3046 is junction
> isolated)...also, the THAT 3xx transistor arrays are dialectically
> isolated, so you don't have to worry about which pin is more negative
> that
> which...
> 
> However, in general, building your own OTA is sortof a loosing
> proposition.  However, I have made simple OTA's, using a THAT340 PNP/NPN
> array (two NPN's and two PNP's) that work out pretty good for cloning
> the
> SSM2040 VCF...still...it is a rather expensive solution...
> 
>         -Jim
> 
> At 03:13 AM 4/9/2005 +0300, Samppa Tolvanen wrote:
> On Apr 9, 2005 1:43 AM, Tim Ressel <madhun2001 at yahoo.com> wrote:
> > Yo,
> >
> > Don't forget the oft overlooked pin 13 requirement.
> > The substrate of the IC (pin 13) needs to be at the
> > lowest voltage the part is likely to see. Otherwise
> > some internal dides conduct and spoil the party. Keep
> > this in mind when designing Q5 into your circuit.
> >
> > --Tim Ressel (rubbing the scar where he was bit...)
> >
> ?
> Could MAT-04's have some "bias". pleaseee? LIke a negative one-- down
> there.. anx, Samppa
> 害. Down  I went
> 
>         -Jim
> ***************************************************************
> http://www.oldcrows.net/~patchell
> 
> ***************************************************************
> 
> 
> 
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