I am trying to build a small amplifier with a JFET J113 to get a high input impedance. I have a problem with the datasheet:

On page 3 it gives a value of IDSS=2mA for J113. However, on the following pages it shows universal curves for all three JFETs J111, J112 and J113.

On figure 5 you find that all these transistors have at least 18mA at VGS=0V.

Which value should I use? If it is the one from page 3, will I have to calculate my own curve using the general JFET-models or can I still somehow use the graphs?

  • 1
    \$\begingroup\$ Page 3 is a minimum value. Figure 5 gives typical characteristics. Yes the spread really can be that large. Design so taht the spread doesn't matter. \$\endgroup\$ – user_1818839 Nov 25 '20 at 19:45
  • \$\begingroup\$ That makes sense! Meanwhile I measured a few samples and they were perfectly in line with the graphs. Thanks! \$\endgroup\$ – Veit Held Nov 26 '20 at 19:25

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