Two-Port Network Parameters
h-Parameters (Hybrid)
Called hybrid because they mix different units.
$$ V_1 = h_{11} I_1 + h_{12} V_2 $$
$$ I_2 = h_{21} I_1 + h_{22} V_2 $$
- h₁₁: \( \frac{V_1}{I_1} \) (with \( V_2 = 0 \)) – Input impedance
- h₁₂: \( \frac{V_1}{V_2} \) (with \( I_1 = 0 \)) – Reverse voltage gain
- h₂₁: \( \frac{I_2}{I_1} \) (with \( V_2 = 0 \)) – Forward current gain
- h₂₂: \( \frac{I_2}{V_2} \) (with \( I_1 = 0 \)) – Output admittance
Commonly used in transistor modeling.
g-Parameters (Inverse Hybrid)
$$ I_1 = g_{11} V_1 + g_{12} I_2 $$
$$ V_2 = g_{21} V_1 + g_{22} I_2 $$
- g₁₁: \( \frac{I_1}{V_1} \) (with \( I_2 = 0 \)) – Input admittance
- g₁₂: \( \frac{I_1}{I_2} \) (with \( V_1 = 0 \)) – Reverse current gain
- g₂₁: \( \frac{V_2}{V_1} \) (with \( I_2 = 0 \)) – Forward voltage gain
- g₂₂: \( \frac{V_2}{I_2} \) (with \( V_1 = 0 \))
Key Differences
| Feature | h-parameters | g-parameters |
|---|---|---|
| Form | V₁, I₂ dependent | I₁, V₂ dependent |
| Nature | Hybrid | Inverse Hybrid |
| Usage | Transistor circuits | Less common |
Summary
h-parameters: Input current and output voltage control behavior
g-parameters: Input voltage and output current control behavior