Hey Loren, nice post -yea the first pass at getting Cf=0.175pF seemed a low.
I am guessing the reason the original calculation for Cf was too low was the unity gain closed loop bandwidth of 1.8GHz was used in Eq. 2 where that should have been the GBP, more like 900MHz - Eq. 1 is implicitly solving to place the feedback pole at Fo. that will give a Q=1 and likely the final Cf shown was slightly increased to empirically reduce the peaking (1.25dB) from that condition.
I touched on these issues a bit in a new blog showing up on PLanet Analog, Feb. 3, 2019.
The latest direct radio frequency (RF)-sampling transceivers provide a number of powerful capabilities that enable advanced system features like multiband and multimode operation, as well as frequency translation and fast frequency hopping.
Although the name seems generic enough to encompass all kinds of voltage transients, electrical fast transients (EFTs) are pulses in systems that come as a result of a voltage source suddenly switching onto or off of an inductive load.