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Altera_Forum
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16 years ago

Arbitrary Waveform

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 ...
Altera_Forum's avatar
Altera_Forum
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16 years ago

Yes, I took as granted, that an external DAC would be necessary with any programmable logic device. 8-Bit amplitude resolution defines the number of data bits, a second design parameter is the number of LUT entries.

A CPLD must implement a ROM in logic cells, most smaller CPLD won't have enough resources to represent an arbitrary look-up table. But the logic is minimized by the design compiler, in some cases it may be sufficient. I suggest to define the table coding and let Quartus try to fit it to different CPLD.

FPGAs have internal memory, that can be used as a ROM, so it's much easier with it. As another point, at low and medium speed, a PWM or SD modulator 1-Bit DAC can be used with a low-pass to generate the waveform.