Per channel Sampling rate of AD7606C-18 and possibility of two-ADC setup for 16-channel simultaneous sampling?

Hi Paul,

The high bandwidth mode enables for faster settling agains step response, if that´s what you are loooking for. See figures 63 through 68 on the datasheet for details.

This mode has a penalty on noise perfomance if that´s ok, see figures like FFTs, SNRs and page 30 for more details.

CN0148 should still be applicable because they newer device can be used as pin replacement. One major point to take into account is the fact that AD7606C-18 has a memory map, so you need to provide access to SDI (serial) or RD (parallel) pin. See this app note about migrating from AD7606 to AD7606B, it´s also applicable to AD7606C AN-1559 (Rev. 0) (analog.com)

Regards,

Lluis.

Hello Lluis,

Thank you for clearing things up. One thing I still do not understand is the sampling frequency per channel. Is it 1MSPS/8 = 125KSPS (sampling time of 8us) per channel? which would mean I could only sample the smallest pulse of width 16us?

Regards,
Shubham Paul

Hi Shubham Paul,

No, this is a simultaneous sampling ADC, 8SAR ADCs on chip, so all of them sample at 1MSPS.

Thanks,

Lluis.

Hi Lluis,

Thanks for the quick response. Just to confirm, so does this mean I could sample eight different pulses of a minimum width of 2us (for each pulse) simultaneously on all the channels?

Regards
Shubham Paul

Hi Shubham Paul,

Well, what info are you trying to extract? Just detecting the pulses? What voltage amplitude are these?

Note that internally there is a LPF, and you can find the frequency and phase response on figures 79 and 80.

As a matter of pen-and-paper exercise, if you create a simple 1st order LPF, with a similar cutoff frequency, you would see 10dB+ attenuation at 500kHz, see below what you´d see at the filters output. This is a theroteical exercise, a filter response. In addition you´d have to take into account the actual settling time mentioned before (figure 63), and that you are sampling just to 1MHz.

Regards,

Lluis.

Hi Lluis,

Thanks again for your detailed info, that would be useful for me. The pulse would have an amplitude ranging from -1V to +1V. I need to measure the amplitude of the 16 different single pulses which would vary between the above range.

Regards,
Shubham 

Hi Shubham,

Then, as described above, you won´t be able to faithfully recontruct your input signal.

Regards,

Lluis.

Hello Lluis,

Thank you for your reply. One final question then, what would be the shortest (approximately) pulse I could measure with this ADC? I mean the practical safest option (for the pulse width) considering the internal LPF and other factors like settling time, etc. Really sorry for asking so many questions, I am not that strong in this area (still learning).

Best,
Shubham.