A pair of matched bipolar transistors for an input stage has emitter areas matched to…
PHYSICS · Subjective · Fermi University Physics · Electronics, Instrumentation & Communication · Semiconductor devices and analogue circuits · Semiconductor devices and analogue circuits
Inside the Instrument, Ch The differential pair and the current mirror
Problem
A pair of matched bipolar transistors for an input stage has emitter areas matched to within 2% of each other, giving the same percentage mismatch in IS. The two collector resistors are film resistors each specified to 1% tolerance; two independently drawn resistors of that tolerance can differ from each other by up to twice the individual tolerance in the worst case. Using VT=25.9mV at 300K, estimate the worst-case input offset voltage of this pair and its drift with temperature at 300K.