Hybrid-pi model: Difference between revisions

Revision as of 02:52, 21 November 2015

Revision as of 02:53, 21 November 2015

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where:

* <math>\scriptstyle \beta_0 ~=~ \frac{I_\text{C}}{I_\text{B}} \,</math> is the current gain at low frequencies (generally quoted as ''h''_fe from the [[Bipolar junction transistor#h-parameter model|h-parameter model]]). Here <math>\scriptstyle I_\text{B}</math> is the DC (bias) base current. This is a parameter specific to each transistor, and can be found on a datasheet.

* <math>\scriptstyle r_\text{o} ~=~ \left.\frac{v_\text{ce}}{i_\text{c}}\right\vert_{v_\text{be} = 0} ~=~ \frac{1}{I_\text{C}}\left(V_\text{A} \,+\, V_\text{CE}\right) ~\approx~ \frac{V_\text{A}}{I_\text{C}}</math> is the output resistance due to the [[Early effect]] (<math>\scriptstyle V_\text{A}</math> is the Early voltage).