Description:
ADC08D1520RB is unable to digitize the sine wave fed in and only noise is observed on WaveVision.
The sine signal frequency is 100MHz and level is -1dBm and -2dBm.
over_range LED flash is observed.
Questions:
1. how to solve it?
2. Does WaveVision and FPGA image of ADC08D1520RB change recently?
Hi Jim,
Thank you for your reply. Please find the answers as following.
Is the input signal a continuous sine-wave?
Yes
Which balun board are you using to convert the signal from the generator to differential?
ADC-WB-BB (I used it but only observe noise. the photo was taken while the board does not connecting with the balun)
Are the DC-Blocks utilized in between the balun board outputs and board inputs?
No
Which inputs (I+/- or Q+/-) is the signal connected to?
Tried both of I + and I- and only noise is observed.
Can you send a picture of your setup, along with a snapshot of the Wavevision GUI showing the time domain waveform and board configuration (input and sampling mode and capture depth are the most important)?
Best regards,
Jim B
Hi Bridget
Thanks for the additional information. Please note that the analog inputs are internally biased to the ADC Vcm (common mode input voltage). Therefore any external signals must be connected using DC-blocks to prevent the external signal from pulling the input voltage below the proper common mode voltage.
In addition, the inputs must be driven with a differential signal applied at V_IN+ and V_IN-. The supplied balun boards and DC-blocks should be used to adapt the single ended output of your signal generator to the differential inputs as shown in Figure 2 of the ADC08D1520RB user guide, also copied here:
Please try connected your signals as shown in the diagram, including using the DC-blocks and let me know if you are able to get the expected results.
Best regards,
Jim B
Thank you very much for your reply, Jim.
Hi Bridget
For that mode and with a 100 MHz input at -1dBm applied to the balun board this is what the time and frequency domain plots should look like:
Time
Frequency
I also tried applying a SE signal directly connected to VIN- with no DC block. Here is what that looks like, the distortion caused by driving the input in that manner is evident, but there is some resemblance to a sine wave.
Please confirm your signal generator output using an oscilloscope. If the signal is as expected and you are still unable to get the expected capture into the ADC08D1520RB please proceed with a warranty return.
Best regards,
Jim B
