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=== Derived parameters ===
=== Derived parameters ===
The following parameters relate to the transistor constants. They are also constants, but are derived from the more fundamental constants given above.
The following parameters relate to the transistor constants. They are also constants, but are derived from the more fundamental constants given above. As the fundamental parameters are different for each transistor, there is a different set of derived parameters for each transistor.
* <math>V_0 = NF \!\cdot\! Vt</math>
* <math>V_0 = NF \!\cdot\! Vt</math>
Another characteristic equation of transistors is
Another characteristic equation of transistors is
: <math>Z \!\cdot\! I_b = IS \!\cdot\! \exp \left( \frac{V_{be}}{V_0} \right)</math>.
: <math>Z \!\cdot\! I_b = IS \!\cdot\! \exp \left( \frac{V_{be}}{V_0} \right)</math>.
This equation is linearized by performing a Taylor expansion up to the first degree, which gives
: <math>Z \!\cdot\! I_b = Q \!\cdot\! (V_0 + V_{be} - U)</math>.
Under AC conditions this equation is modified by defining <math>V_0 = U</math>. There is one such equation for each transistor
* <math>T_1</math>: <math>Z_1 \!\cdot\! j_b = Q_1 \!\cdot\! (V_{01} + V_3 - U_1)</math>
* <math>T_2</math>: <math>Z_2 \!\cdot\! K_b = Q_2 \!\cdot\! (V_{02} + V_7 - V_4 - U_2)</math>