Specification Question of PXIe-5842: maximum bandwidth calculation

Updated Sep 27, 2024

Reported In

Hardware

  • PXIe-5842

Issue Details

I'm reading the specification of the new VST PXIe-5842, and found that in Table 4 "*" annotation, there's "50MHz" in the equation. Why there is a 50MHz in the equation? Any reason behind it?
5842-specification.JPG

Solution

You could easily understand it if the center frequency of a signal is plotted on a chart as below.

Let's say we have a target signal centered at 350 MHz, and you could find that it's only 300MHz distance wide to the left bound (50MHz of PXIe-5842) :
bw_max.png

So the equation int Table 4 is just used to try to find the appropriate Maximum BW for that particular center frequency by checking whether it's bounded by the right bound(2GHz - Cf) or the left bound(Cf - 50MHz) or 1GHz.

Maximum Bandwidth = min[1 GHz, 2 x min(Center Frequency - 50 MHz, 2 GHz - Center Frequency)]
                  = min[1 GHz, 2 x min(350 - 50 MHz, 2 GHz - 350)]
                  = min[1 GHz, 2 x min(300 MHz, 1.650 GHz )]
                  = min[1 GHz, 2 x 300 MHz]
                  = min[1 GHz, 600 MHz ]
                  = 600 MHz
Note: Please notice that there are 3 columns in Table 4 as there are 3 models of PXIe-5842 each with different RF frequency ranges, so the corresponding maximum bandwidth would be different as well.
 

Additional Information

Please refer to the "Optimized RF Front End" section in this article to get to know more about the 'Direct Sampling' mode of PXIe-5842 under 1.75GHz.