High bandwidth Sawtooth Generator

Hi,

I need a TTL triggered sawtooth generator with a very fast falling slope of the sawtooth (see attached graphics) (slope < 1 ms or a bandwith of min. 160 kHz) and I wounder with which Arduino board (or combination of boards) this could be realized best.

TTL triggering would not be a problem, I think. I would use an interrupt input for this.

But for the sawtooth signal I’m afraid, I need a DA-converter with a very fast settling time and a high sampling frequency – do I? Isn’t there a baord I simply could connect to UNO, which would almost meet this specifications?

Let me know if you would need more information.

Olli

Have a look at DAC chips (digital-to-analog converters), such as the MCP4822. They are much faster than you have requested, and are interfaced to the Arduino via SPI. There's an SPI library to handle the hardware-accelerated interfacing. Oh, and the MCP4822 is a dual DAC.

Thanks for your reply!

Another stupid question: Would the AD5426 ( http://www.analog.com/en/digital-to-analog-converters/da-converters/ad5426/products/product.html ) DAC work as well with the SPI library and would you add an anti-aliasing filter?

... I meant 1 us not 1 ms settling time, sorry.

TIA, Olli

ollig: Thanks for your reply!

Another stupid question: Would the AD5426 ( http://www.analog.com/en/digital-to-analog-converters/da-converters/ad5426/products/product.html ) DAC work as well with the SPI library and would you add an anti-aliasing filter?

That chip should work with the SPI library. Note that the SPI library can only send 8 bits of data at a time, so any chip that needs, say, 12 bits may cause a problem. You may be able to send 16 bits and let the chip ignore 4 of them. In my case, with the MCP4822, it needs a 16-bit data packet so I simply send two lots of 8-bit data.

Anti-aliasing filters are only really used with ADCs, but a low-pass filter could be used with a DAC. If you do use a filter, it will remove high frequencies and may, therefore, slow down the fast edges in your sawtooth.

ollig: ... I meant 1 us not 1 ms settling time, sorry.

Ah, now I understand why your original message sounded odd!

Thanks for your help. I've learned a lot! I will try it like this!