[sdiy] CA3280 VCA Design

[ASSI]

On Montag, 21. November 2005 15:22, Grant Richter wrote:
> As I recall, you run the voltage straight in through a resistor, tie
> the first (predistortion) section back to it's own input and into the
> input of the gain control cell.
> The first section will generate the compensation curve needed to
> produce a full level linear output after the gain control block,
> without input attenuation.
> This allows you to run full +/- 10 volt signals through the OTA. The
> monolithic matching of the LM13700 sections should allow the
> compensation to be perfect.

There is one drawback this method shares with the diode linearization: 
the input impedance drops dramatically as in effect you create a 
current rather than voltage input. It appears that quite a few circuits 
would not work unchanged without an extra buffer at the input (with all 
the problems that a buffer can create).


Achim.
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