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Fast Analog digital converting

Reza Rebk
Prodigy 40 points
Other Parts Discussed in Thread: DEV-ADC34J22, HSMC-ADC-BRIDGE

Dear All
I am a university student. I have to connect an ADC to my DE2-115 Altera development board. 
First problem is, finding a proper ADC for my research but my Analog signal is a kind of special. Low frequency and very low duty cycle as frequency is 10 Hz and only 40 to 200 ns duty cycle (means 100 ms pulse with only 40 to 200 ns duty cycle). Therefore I need a fast ADC to could catch this narrow duty cycle. In the other hand, ADCs with high sampling rate do not work with low frequencies like as 10 Hz! 
Can you help me and give me an idea to solve this problem! 
2nd problem: I have bought a DEV-ADC34j22 module without notice that it is designed for Cyclone V GT and now I have DE2-115 Altera! I am hoping for some modification like as pin assignment for its HSMC to use it for DE2-115 board! Is it possible! Can you suggest me some alternative ADC for mentioned converting ! 
Thank you.

  • 0
    TI__Mastermind 43860 points

    Hi Reza

    The DEV-ADC34j22 module has a JESD204B high speed serial data interface, and for that reason is not compatible with the DE2-115 development board.

    So your options are to either get a different capture/development board that is compatible with the DEV-ADC34j22, or find another ADC EVM solution that is compatible with the DE2-115 board.

    Many of the TI high speed ADC EVMs have high speed LVDS interfaces, and could be compatible with the DE2-115. The http://www.ti.com/tool/hsmc-adc-bridge is intended to adapt the connector on the ADC EVMs to the HSMC used on many Altera development platforms. You will need to review the pinout of the HSMC connector on the Altera board along with the HSMC-ADC-Bridge and ADC EVMs to determine if the signal interfaces are compatible. The DE2-115 User Guide indicates that the HSMC connector supports LVDS operation, but the 100 ohm termination resistors may need to be installed.

    Your indicated signal pulse width is around 40ns to 200ns. To ensure at least 10 samples are captured in a 40 ns period will require a sample rate of around 250 MSPS. If that speed is suitable an ADC EVM like this http://www.ti.com/tool/ads41b49evm might be a good fit. If you don't need that many samples of the pulse then lower sample rates could be used.

    I hope this is helpful.

    Best regards,

    Jim B