Question about board level connection of a BJT, with external bias current source

[bhl777]

Hi, I have one fabricated BJT device (not power BJT) and want to use an external uA current to bias it. However, I have some questions about the board level connecting, and would anybody advise me about the four questions in the picture? Thank you!

 

[D.A.(Tony)Stewart]

Without knowing the EMI immunity of the layout, you must consider the breakdown voltages for each terminal to protect it from excess reverse voltage One diode could be used for this purpose especially with inductive lines and open circuit with current. Keep the Current loop small in area with coax or twisted pair and you may still need a CM choke.

Beware of ESD damage and use whatever protection diodes, TVS etc to protect the device leads and capacitive discharge on connections.

 

[bhl777]

Without knowing the EMI immunity of the layout, you must consider the breakdown voltages for each terminal to protect it from excess reverse voltage One diode could be used for this purpose especially with inductive lines and open circuit with current. Keep the Current loop small in area with coax or twisted pair and you may still need a CM choke.

Beware of ESD damage and use whatever protection diodes, TVS etc to protect the device leads and capacitive discharge on connections.

Thank you SunnySkyguy! I revised the connection scheme, and would you answer my questions in the picture? Thank you!

 

[erikl]

I revised the connection scheme, and would you answer my questions in the picture?
View attachment 120371

I think you shouldn't leave the pnp's bulk floating. Better connect it to the most positive potential, together with the 2V Zener's cathode. Or - if this isn't possible - to the emitter.

A 2V-Zener will have a non-negligible leakage current. Measure it and adjust your current source.