analog circuit generating powers of a value

[preethi19]

Hi is there any analog cmos circuit that generates say 2 to the power of... Or like 3 to the power of any value. Not looking for a squarer but like to use any independent power value. not looking for exponential function either. Like something generating 4^5.... Its like i should be able to choose any base value and have it fixed say for eg 4 and vary the exponent from certain range.. Pls help.. Thank you!!!

 

[BradtheRad]

If you wanted 1/e to the power of x... then you can use the capacitor discharge curve. Or rather, a mirror image of it.

The capacitor discharge curve is time related. Vnow= Vstart x (1/e)^t.
This probably does not suit your purpose.

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Or possibly a diode junction response. There may be a portion of the diode curve (V versus A), that resembles what you are looking for.

However I once tried to match my real data to an equation, and the best I could find was A= (V x 1.25) ^ 20. It is not the type of equation you want. Mine is a y=x^20 type equation.

You are looking for y=2^x, or y=3^x.

 

[schmitt trigger]

Probably a single circuit by itself will not do it. But several cascaded circuits would. Like Log-Multiplier-Antilog.
That is how analog computers worked.

 

[d123]

Hi,

Multiplier op amps seemed to cost about $30. There is a multiplier/divider, a root extractor and a cube generator schematics (towards the end) using op amps in the pdf:

View attachment Op Amp Circuit Collection AN-31 NatSemi.pdf