H parameter equivalent circuit
The input circuit appears as a resistance h11 in series with a voltage generator h12 v2.
The output circuit involves two components ; a current generator h21 i1 and shunt
resistance h22.
Performance of a Linear Circuit in h Parameters
(i) Input Impedance:
Now, i2 = h21 i1 + h22 v2 in terms of h parameters, and from the figure i2 = - v2/rL. So,
If either h12 or rL is very small, the second term in exp. (iii) can be neglected and input
impedance becomes :
(ii) Current gain: referring to the figure, the current gain Ai of the circuit is given by:
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(ii) Current gain: referring to the figure, the current gain Ai of the circuit is given by:
(iii) voltage gain:
Referring to the figure again, the voltage gain of the circuit is given by:
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Transistor h parameters
For small signal transistor behaves like a linear circuit.
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The h-parameter formulas (CE configuration):
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