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Altera_Forum
Honored Contributor I
962 Views

Frequency supported by THDB_ADA of Terasic

Hello, 

I am confused about the maximum frequency supported by this DAC card. The specs say it is upto 125Msps but in the GUI the frequency does not go beyond 5Mhz. Can someone point out the discrepancy? 

 

Regards, 

Ranjan
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5 Replies
Altera_Forum
Honored Contributor I
51 Views

 

--- Quote Start ---  

Hello, 

I am confused about the maximum frequency supported by this DAC card. The specs say it is upto 125Msps but in the GUI the frequency does not go beyond 5Mhz. Can someone point out the discrepancy? 

 

Regards, 

Ranjan 

--- Quote End ---  

 

 

Ha, I was stuck with this for quite sometime. The discrepancy is because of the bandpass transformers at the inputs to the ADs. Check the schematics for the board and look up the part numbers of those transformers. Post back if you need more help with this. 

 

You can search this forum and there were some posts from quite a while back about removing those coupling transformers. Personally, I have gone back to parallel ADAs :D. No more issues with buffering serial data :D. 

 

Bharath
Altera_Forum
Honored Contributor I
51 Views

The DACs are good for at least 125 MSPS (60 MHz signal frequency), as Bharath mentiions, there's a lower frequency limit (about 0.5 MHz) set by the transformers.

Altera_Forum
Honored Contributor I
51 Views

Thanks bharath and FVM, 

My application requires to generate 120Mhz of sine wave, so I guess I cannot do with this DAC. To be safe I would like to have eight samples per cycle which means around 1GHz of sampling rate. Can you please suggest some DAC'S with this specification that comes with HSMC port(As I am using Cyclone 3 FPGA with HSMC). 

 

Regards 

Ranjan
Altera_Forum
Honored Contributor I
51 Views

 

--- Quote Start ---  

 

Can you please suggest some DAC'S with this specification that comes with HSMC port(As I am using Cyclone 3 FPGA with HSMC). 

 

--- Quote End ---  

Texas Instruments have some 1GHz DACs (DAC5681 and DAC5682); 

 

http://www.ti.com/tool/dac5682zevm 

 

and they have an HSMC adapter which might be compatible (you'll have to do the research); 

 

http://www.ti.com/tool/hsmc-adc-bridge 

 

Cheers, 

Dave
Altera_Forum
Honored Contributor I
51 Views

Thanks a lot DWH for the quick response. I will look into the specifications. 

Regards, 

Ranjan
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