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Altera_Forum's avatar
Altera_Forum
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15 years ago

THDB_ADA daughter board

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

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    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's avatar
    Altera_Forum
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    15 years ago

    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's avatar
    Altera_Forum
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    15 years ago

    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's avatar
    Altera_Forum
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    15 years ago

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

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    --- 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