AD9286 Logic Level Voltage

Hi,

I am currently using the AD9286 board. At the moment, I am just trying to measure the output voltage of each binary bit at logic '1' and logic '0'. I was able to measure, using DVM, a voltage of 1.8V for the negative bits (D0- to D7-) and 0.5V for the positive bits (D0+ to D7+) when the board is powered up, with no clock or input.
But the introduction of a clock and an input of 0V resulted in the first four bits (D0- to D3- and D0+ to D3+) to output a voltage of 1.2V. The remaining bits remained the same.

I would like to ask:
1) I have not configured the board using any software yet. Is it necessary in order to get the voltage values?
2) Is it possible to measure the voltage range of each bit by just using a DVM? Is my approach possible?
3) If it is, what mode should I be operating the board is? CMOS, LVDS or SPI?

Any help is much appreciated. Thanks in advance

  • 0
    •  Analog Employees 
    on Jun 28, 2013 5:57 PM

    Hi,

    These outputs are differential LVDS, so when you power up and don't clock the ADC, the bits are static and at the logic levels as you descibe.  When you start clocking the device with no input signal, the output data will still reflect the thermal noise of the ADC, so the LSBs will start to toggle.  In this case the DVM is only measuring the dc content, or common mode voltage of the LVDS outputs, which is 1.2V.   You will need a scope to observe the bits when they are switching.  Will you also be using the HSC-ADC-EVALC data capture board to evaluate the AD9286?  If so you can use the logic analyzer feature of the Visual Analog software to see the output data. 

    Regards,

    David

  • Hi David,

    Thanks for your quick reply. And I apologize for taking so long to get back  to you. Unfortunately I will not be using the HSC-ADC-EVALC board. My intention is to integrate the AD9286 with an FPGA board. That was why I wanted to find out the voltage level I will be working with. But I will heed your advice and attempt to observe the bits using a scope. Thank you again for your help. Much appreciated.

    Regards,

    Hanif