[sdiy] Some OTA questions

[James Patchell]

One way to look at Id on the CA3280 (or the LM13700 for that matter) is a 
way of controlling the amount of attenuation you get at the input.

If you go to my webpage...

http://www.oldcrows.net/~patchell/archives/ca3280_3.html

http://www.oldcrows.net/~patchell/archives/ca3280_4.html

http://www.oldcrows.net/~patchell/archives/ca3280_2.html

you will see some plots and a schematic which will (hopefully) shed a 
little light....the schematic shows the differences on how a CA3080 and 
CA3280 are connected to make a VCA...



At 11:06 PM 11/25/2005 -0500, Jeff Farr wrote:
>I've been working my way through the EN app. notes on the 3080 and
>there are some nagging questions left, first, there is an example of a
>S&H circuit where a 3080 in switch mode is feeding a capacitor with a
>FET buffer.  If I understand this correctly Vdiff simply switches on
>the 3080 and since Iout = Ic it's Ic that is doing the "sampling" so I
>would connect my source (noise) to that.  Do S&H's usually work with a
>current in?  Second, I haven't yet figured out how to make use of Id
>in a 3280, can someone point me to a good app note about that?  What
>about the differences between a 3*80 and one of the LM1*00 OTA's?

         -Jim
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