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THDB_ADA daughter board

Altera_Forum
Honored Contributor I
793 Views

Hi  

 

I am working with the THDB_ADA daughter board connected to the DE2 board. 

as i know, the input voltage range to the A/D is 2V p-t-p. 

when i'm supplying siganl vary between 0v and 2v, i'm expecting to get the HEX number "3FFF" for the 2v. insted i'm getting other HEX numbers, much below "3FFF", and have no idea why. 

 

is there anyone who have experience with the THDB_ADA daughter board that can help or give some useful information? 

 

Any help is appreciated
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5 Replies
Altera_Forum
Honored Contributor I
102 Views

Did you view the THDB_ADA schematic and realize, that it can't measure DC and low frequency AC due to the transformer coupled input?

Altera_Forum
Honored Contributor I
102 Views

yes i did. i'm supplying AC siganl from function generator, the signal vary between 0v and 2v, ferquency is 5 to 10 mhz.

Altera_Forum
Honored Contributor I
102 Views

5 or 10 MHz should perfectly work. The nominal input range would be actually 2 Vpp at the input connector, respectively about 10 dBm. You should use an oscilloscope to check the real input voltage, both at the input connector and the ADC inputs. 

 

P.S.: The signal generator must be able to drive 50 ohm, of course.
Altera_Forum
Honored Contributor I
102 Views

Thank you FvM, i'm working on it, hope to find what i'm doing wrong..

Altera_Forum
Honored Contributor I
102 Views

 

--- Quote Start ---  

5 or 10 MHz should perfectly work. The nominal input range would be actually 2 Vpp at the input connector, respectively about 10 dBm. You should use an oscilloscope to check the real input voltage, both at the input connector and the ADC inputs. 

 

P.S.: The signal generator must be able to drive 50 ohm, of course. 

--- Quote End ---  

 

 

Would you please send me the QUARTUS project to test ADC and DAC of thdb_ada daughter board with Cyclone III starter kit? Thanx
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