⊿ BJT & MOSFET Calculator

DC bias, operating point, and switching analysis for transistors

Voltage Divider Bias (most common): R1 and R2 set the base voltage; RE provides stability. Enter all values to find the Q-point (IC, VCE).

BJT Voltage Divider Bias

Vcc (V)

β (hFE / DC gain)

R1 (kΩ)

R2 (kΩ)

RC (kΩ)

RE (kΩ)

VB (Base)

—

VE (Emitter)

—

IC (Collector I)

—

VC (Collector V)

—

VCE

—

IB (Base I)

—

BJT: VB = Vcc × R2/(R1+R2) | VE = VB − 0.7 | IC ≈ IE = VE/RE | VCE = Vcc − IC×(RC+RE)

MOSFET Saturation: ID = (Kn/2) × (VGS − VTH)² if VDS > VGS − VTH

MOSFET Linear: ID = Kn × [(VGS−VTH)×VDS − VDS²/2] if VDS < VGS − VTH

BJT Switch: IB_min = IC / β | Add ×3 safety factor | RB = (Vin − 0.7) / IB