0xFF

https://www.eevblog.com/forum/chat/50g-ohm-retirement-fund/

Electrometers. At work I routinely use 20G and 100G resistors and plan to use SMD parts of these values in a near future. The application in my case is Quadrupole Mass Spectrometry. Similar electrometers are used in many other applications where very small charges/currents have to be measured or sensed. The current noise level is reduced with the increase in the resistor value, so larger the value, lower the noise (but slower the response due to a parasitic capacitance). 20G resistor has about 1fA RMS self-noise in 1Hz BW. 50G resistor - about 0.6fA. I can also add that it is perfectly possible to use SMD parts with these values. If somebody would like to know the details, than the ADA4530-1 datasheet, evaluation board description and AN-1373 application note can provide a good starting point.