3
\$\begingroup\$

I'm trying to remember the approximation for the value of the diffusion capacitance for a bipolar power transistor. I think it might have been gm/Ft? Can anyone confirm this and/or give a reference? Thanks!

\$\endgroup\$
2
\$\begingroup\$

Good old Sedra and Smith fourth edition, pg 322 has the formula as \$C_{de} = \mathrm{T}_{f}*g_m\$ and has a note that \$\mathrm{T}_f\$ is usually in the 10 to 100 picosecond range. It looks like your formula is equivalent.

\$\endgroup\$
  • 1
    \$\begingroup\$ Right-click the formula and select "show source" from the MathJax context menu :- \$C_{DE}=\tau_F.g_m\$ \$\endgroup\$ – MikeJ-UK Apr 28 '11 at 8:01
  • \$\begingroup\$ @Mike, I didn't know you could do that! Nice... \$\endgroup\$ – Adam P Apr 29 '11 at 21:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.