Are PIN diodes available? How about laser trimmed ...
# sky130
Are PIN diodes available? How about laser trimmed resistors? (especially in regards to the shuttle)
MOSFETs make good RF switches, and don't need the impractical bias inductors and bias current that you would need with a PIN diode. You can trim resistors by switching parts in or out with MOS switches, and store the trimming word in FLASH if you like. The ratio between resistors will be very accurate even with no trimming, much better than typical resistors on a PCB. It does help to use the same unit resistor in series-parallel combinations to make up resistors that have to match each other, and make the layout around the resistors uniform, e.g. by placing them in a regular array with dummy resistors around the edge. Also get used to thinking about the metal resistance in the traces, it is surprisingly bad compared to a PCB.
Thanks for the info. I'll keep that in mind as I go I'm just waiting on spice models (I hear they should be coming in the next week or two?)