Tera = \( 1 \times 10^{12} \)In the data sheets for an op amp, units of input resistance are given as T Ohms. What does "T" stand for, please?
Thank you if you know,
Pete
So what is the DC resistance of a capacitor? How about the gate of a garden variety FET?It would stand for Tera (1000 Gigaohms). That seems a bit high to me...
10 or 10's of gigaohms, but I've never seen 100's or 1000.How about the gate of a garden variety FET?
Only theoretically. It is likely/certain that the opamp packaging, atmospheric moisture and surface contaminants on the pcb will drastically reduce the resistance seen.the source "sees" an input resistance of 1.5 T Ohm, is that correct?
This is an important point. When impedances start getting that high, little things that are normally insignificant start becoming significant. Maybe not significant for your design, but significant relative the 1.5T specification.Only theoretically. It is likely/certain that the opamp packaging, atmospheric moisture and surface contaminants on the pcb will drastically reduce the resistance seen.
A MOSFET input is a capacitor but a JFET has a reversed biased diode as the input (hence Junction FET).The gates of JEFTs and MOSFETs on the inputs of opamps are basically little capacitors.