I am capturing data from AD6688-3000EBZ using ADS7-V2 board and ACE (Version 1.12.2718.1186). When I apply a tone with 1.7 Vpp I expect the maximum on the DDCFFT graph to be 0 dB ( corresponding to full scale) however it is approx. -30 dB. İs this a conversion issue or something is wrong ?
Where are you measuring 1.7Vpp? See https://www.analog.com/en/analog-dialogue/raqs/raq-issue-129.html for more info.
I am applying 3 dBm tone to the input of the eval board. Increasing the power does not increase the measured peak in the DDCFFT graph. 3 dBm seems to be the saturation point . @ 3 dBm input level DDCFFT peak is - 27 dB.
1.7 Volt considering 200 ohm input imdedance of the ADC corresponds to aprox. 2.5 dBm. Taking into account the loss of the balun (Marki BAL-0006) -7 dB and additional 6 dB loss due to mismatch between balun output and adc input impedance (100 ohm to 200 ohm) I expect saturation level to be around 15 dBm.
I am using complex output and activated 6 dB DDC gain.
Thanks. I am sending you the screenshots you requested. Tone signal is - 3 dBm. Increasing the power does not affect the peak level in DDCFFT graph.
What if the same signal was sent on channel B? does it show the same phenomenon?
It must be the signal generator then. Does reducing the power result in a reduction of the amplitude seen in the FFT? If you are using the AD6688-3000EBZ, by default, you will need about 12-15dBm or so, in order to get to -2dBFS.
Hi UmeshJ, With 15 dBm input I get - 2 dB FS. Thanks for your help.