To calculate the output impedance of a network using h-parameters (also known as hybrid parameters or ABCD parameters), you need to first determine the h-parameters for the network. H-parameters describe the relationship between voltage and current at the input and output ports of a two-port network.
A two-port network has two input variables (voltage and current) and two output variables (voltage and current). The h-parameters are represented as follows:
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[voltage_input] [h11 h12] [current_input]
[voltage_output] = [h21 h22] [current_output]
where:
h11: Input impedance with the output port short-circuited (voltage_input with current_output).
h12: Reverse voltage transfer ratio with the input port open-circuited (voltage_input with voltage_output).
h21: Forward current transfer ratio with the output port short-circuited (current_input with current_output).
h22: Output admittance with the input port open-circuited (current_input with voltage_output).
To calculate the output impedance (Zout) using h-parameters, follow these steps:
Find the h-parameters for the two-port network of interest (you might have them given in a circuit diagram or measurement data).
The output impedance (Zout) is given by the formula:
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Zout = 1 / h22
This formula is valid for linear two-port networks where the input and output relationships are linear and the h-parameters are constant over the operating range of the network.
Remember that h-parameters are suitable for small-signal analysis and are often used for transistor amplifier circuits, as well as other two-port linear networks. If the network is nonlinear or the operating conditions significantly deviate from the small-signal regime, other parameter models might be more appropriate.