In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
