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  • TI Thinks Resolved

ADC1175: Jitter problem when sampling sinewave and squarewave

Prodigy 150 points

Replies: 14

Views: 328

Part Number: ADC1175

Hello,

I have a project that continuously sampling ADC In pin on ADC1175 20Mhz but facing a lot of jitters on waveform. I thought problem may be regarding bare wire coming from microchip's clock and connecting ADC's clock pin. And decided to make more investigation and used Inverter before ADC's clock pin by suggestion of Customer Support. But jitters did not go even got worse. Number of jitters increased. 

I attached the screenshots (case.rar) when i used clock signal from microchip without any logic IC (like inverter) and with inverter. How can i get jitters reduced?

Thank you

Regards 

Baris ErdoganCase.rar

  • In reply to Baris Erdogan:

    Hello Dan,

    Did you ever have chance to investigate my update and my new shots?

    Thank you

    Baris Erdogan

  • In reply to Baris Erdogan:

    Hi Baris,

    Thank you for your patience as I acquired all necessary items to perform tests in my lab. Using the ADC1175EVM, we can better isolate the ADC1175 to understand how it behaves in a controlled system.

    Please see the attached document where I test three different analog inputs with a 20 MHz onboard oscillator serving as the sample clock.

    ADC1175EVM_analog input test.pptx

    Unfortunately, there is not much else I can do to help track down the exact issue with your board. My suggestion for you is to order the ADC1175EVM, and perform your own tests to better understand how the device will behave in your design. Or, you can look at how the EVM is designed, and copy this into your project.

    Best Regards.

    Dan

  • In reply to dBrock:

    Hello,

    Does "the place you highlighted with yellow" mean that you took them off from the board during test?

    Are these graphs produced by pure sample data or does your application (HSDC Pro) take average of the sample data?

    Thank you

    Regards

    Baris Erdogan 

  • In reply to Baris Erdogan:

    Hi Baris,

    The highlighted area in the upper left corner is where I applied the analog input sine wave and the capacitor next to it is where I took the oscilloscope measurement for 1 MHz sinewave input.

    The other highlighted area near the middle is the 20 MHz crystal oscillator.

    This is not averaged data, but just a single 65,536 capture.

    You can view the ADC1175EVM design files here http://www.ti.com/tool/adc1175evm 

    Best Regards,

    Dan

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