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Newbie
Newbie
3,448 Views
Registered: ‎01-28-2010

Arbitrary Generator

Hi,

I need to improve the Linearisation of a VCO, For that i need to provide arbitrary waveform see attached between voltage 0 to 5VDC (it is like Triangle waveform but not the same).

I think to insert the values to a PROM (look-up table) and with D/A the CPLD/FPGA will produce the waveform.

Please advice.

Regards,

Doron

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3 Replies
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Teacher
Teacher
3,434 Views
Registered: ‎08-14-2007

Hi Doron,

signal generation using a PROM lookup is a very common and reliable method.

Remember that you can save 50% PROM space when you take advantage of the mirroring properties of that signal.

Also, in your case the PROM method has the advantage, that you can adapt the waveform on a per unit base,

This needs a measurement of the linearisation curve for every VCO, but with data2mem you are able to update the PROM contents of the bitfile without reimplementing your code.

 

Have a nice synthesis

  Eilert

 

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Newbie
Newbie
3,418 Views
Registered: ‎01-28-2010

Hi Eilert,

 

Which device i Xilinx can do the job ?

 

The period of the Waveform is 200uSec and the Voltage is varies between 0VDC to +5VDC.

 

Thanks,

 

Doron

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Highlighted
Teacher
Teacher
3,406 Views
Registered: ‎08-14-2007

Hi Doron,

when you want to use internal memory, you need an FPGA. 

Most any device family can do it, but for a new Design I would recommend some Spartan3 (E/A/AN) device at least.

For the analog output you need en external DAC, so the reference Voltage of that has to be 5V.

The FPGAs today operate below 5V but support various I/O-levels. 

You have to make sure that your FPGA and DAC can communicate on the same I/O level.

Maybe for first breadboard tests you like to experiment with some simple to use modules like the GOP-XC3S200 Module

(http://shop.trenz-electronic.de/catalog/product_info.php?cPath=1_48_137&products_id=626) or one of the newer GODIL Modules.

Also Enterpoint.co.uk has some nice boards for that purpose too.

 

Have a nice synthesis

 Eilert 

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