I have got a AD9912 evaluation board. I hve problem to install the USB driver for the board. Every time when the Window finds the hardware any try to install the driver, it will fail. How can I install the driver properly? Thanks!
It's best to run the software on a 32-bit Windows XP machine, or by running it using Windows XP under Microsoft Virtual PC on a Windows 7 machine. You'll also need admin privileges.
64-bit versions of Windows are not supported at this time.
Download the software from here:
Install the software first, and then connect the board. Windows will attempt to install the drivers. It may give you warnings about an unsigned drivers, or complain that it can't find the driver and prompt you for a disk. If you get that, just select "install from the default location." After a couple of iterations, it will find the driver and the board. There is a USB STATUS LED on the board that should be blinking at this point.
I apologize that the process isn't straightforward. The USB drivers provided by Cypress are older, and using a newer USB driver involves a major rewrite of the code.
If this doesn't work, let me know exactly where it's failing.
Thanks a lot!
It is woking now!
Glad to hear! :-)
I'm using AD9912 evaluation board to generate 242MHz output. The strongest harmonics I saw on the spectral analyzer is at fs/2-fout. It is around 62dBc. Is there any technique to mitigate this signal?
I'm waiting to hear back from another engineer on why you're seeing this.
Are you looking this on the DAC output directly, and not through the reconstruction filter, right?
One possibility is that there are stitching resistors that join the power supplies together, and I don't recall if the power supplies needed to be isolated further for better performance. Can you confirm how the power supplies are connected together?
I was looking at the signal after the reconstruction filter. I have got 2 other spurious signal which I identified as the 3rd (274MHz) and 5th harmonics (210MHz). Those 2 are smaller than the fs/2-fout and can be cancelled.
I am using 1x3.3V and 1x1.8V power supply for the required power supplies. I know this is not good practice. But do you think this is the cause of the fs/2-fout signal?
> But do you think this is the cause of the fs/2-fout signal?
I think this is an excellent place to start looking. Pins 3,5,7 are big producers of noise that contaminate the rest of the supplies if they're not isolated. I'd start by isolating those.
Also, make sure there's a 1k pull-down on the LOOPFILTER pin.
I'm very puzzled by your results, as I'm the one who took the SFDR data on the AD9912, and my results were far better. I used the same board design that you have and didn't do anything special to get very good results for that part.
I’m now using one channel for each power supply point. It is 10dB better. But it is still there. Do you have any suggestions for the power supply? Thanks!
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