DDS with phase marker?

Hello Jimbels,

You can use AD9954 for that by using both the DAC output and the comparator. Or if you prefer staying with AD9102, you can add an external comparator as you suggested. There are many high-speed comparators in the ADI portfolio https://www.analog.com/en/products/analog-functions/comparators/high-speed-comparators-lessthan-100ns-propagation-delay.html

Regards,

Will

Hey Will,

I wasnt sure if the comparator could be used at the same time as the sine wave generator? As I was looking at the AD9954 evaluation board, and it looks like you have to select which output you wish (Note 4 page 36 of datasheet). Have I got this confused? 

Thanks

Jimbles

Hello Jimbels,

The datasheet assumes that you either want a sine wave or a square wave, which is the case for most users. But since you want both you can use both. Depends on how much you care about the alignment between the sine wave and the square wave, you might not want to use two separate filters, especially if the two filters have different transfer functions, which looks like the case in the datasheet. You can potentially just have one differential filter between the transformer and IOUT/IOUTB, and feed the comparator from the output of the filter is kick back is acceptable.

Regard,

Will

Hello Jimbels,

The datasheet assumes that you either want a sine wave or a square wave, which is the case for most users. But since you want both you can use both. Depends on how much you care about the alignment between the sine wave and the square wave, you might not want to use two separate filters, especially if the two filters have different transfer functions, which looks like the case in the datasheet. You can potentially just have one differential filter between the transformer and IOUT/IOUTB, and feed the comparator from the output of the filter is kick back is acceptable.

Regard,

Will

Hi Will,

Thanks again for your input. I think an external comparator might be a good solution in my case. I was looking into the AD9102, and there is the DOUT pin which can be controlled by the pattern generator. Does this still work with continuous waveforms? As that might be a good enough for my needs.

Regards,

James

Hello James,

The DOUT pin can be configured to indicate either the pattern generation is on or off. I am not sure if it works in DDS mode, but even if it does, it will just stay high while the DDS is running, rather than send out a rectified (or MSB) of the sine wave.

Regards,

Will

Ah I see! That makes sense. Thanks for your continued advice

James