BJT currents

Tags

• BJT transistors
• Electronics
• physics
• Electronics formula
• physics formula
• Transistors

Detail

Variables

• $I_C,I_B,I_E$A
• $\alpha,\beta$dimensionless
• $V_{CE},V_{BE}$V
• $g_m$S
• $r_\pi$Ω.

Conditions

• Small-signal NPN unless stated; stay in the named region.

Conventions

• A, V, S or Ω

Related formulas

• Related

  BJT as a switch

  $$\mathrm{state}=\begin{cases}\mathrm{cutoff}&I_B=0\\\mathrm{saturation}&I_B\ge I_C/\beta_f\end{cases}$$
  Open formulaOpen in section

• Related

  Current gain alpha

  $$\alpha=\frac{I_C}{I_E}$$
  Open formulaOpen in section

• Related

  Shockley equation

  $$I_D=I_S\left(e^{v_D/(nV_T)}-1\right)$$
  Open formulaOpen in section

• Related

  Silicon diode threshold model

  $$V_D\approx0.7\ \mathrm{V}$$
  Open formulaOpen in section