Small-signal model: Difference between revisions

Revision as of 04:09, 5 November 2007

Revision as of 04:16, 5 November 2007

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::<math>r_D=\frac {kT/q}{I_Q}\ </math>.

In a similar fashion, the diode capacitance is the change in diode charge with diode voltage:

::<math> C_D = \frac{dQ}{dV_Q} =\frac{dI_Q}{dV_Q} \frac{1}{{\tau}_s_F} + \frac {dQ_J}{dV_Q}=\frac{q}{kT} \frac{I_Q}{{\tau}_s_F} + C_J </math>,

where <math> C_J = \frac {dQ_J}{dV_Q}</math> is the junction capacitance and the first term is called the [[diffusion capacitance]], because it is related to the current diffusing through the junction.