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Old 09-23-2003, 06:35 PM
Andi
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Default atan in a FPGA

Hi folks,

Could any one suggest me how to implemet an 'atan' function in a FPGA?
I've seen the Taylor polinomian but, is there any other way ?

rgds,

Bodhi


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Old 09-24-2003, 03:05 PM
Ralf Hildebrandt
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Default Re: atan in a FPGA

Hi Andi!


> Could any one suggest me how to implemet an 'atan' function in a FPGA?
> I've seen the Taylor polinomian but, is there any other way ?


What about a lookup-table (with linear/binomic/... interpolation)?

Ralf

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Old 09-25-2003, 09:58 AM
Acciduzzu
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Default Re: atan in a FPGA

Hi,

Another solution is to use a CORDIC rotator, working in the so-called
"vectoring mode". This allows you to get the phase and the amplitude
(polar coordinates) of an input vector specified in cartezian
coordinates (X and Y).
M = SQRT(X^2+Y^2);
A = ATAN(Y/X);
What you have to do now is to choose a convenient constant vaue for X
and use Y as your argument to ATAN.
Anyway, you cand find more info on the CORDIC algorithm on the net and
you will se you can do a lot more things with it than just compute
ATAN.
A pretty good example of synthesizable VHDL code can also be found on
www.opencores.org.

Hope this helps

Acciduzzu
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