FPGA Based Digital World - Two-Port Circuit Network

Two-Port Circuit Network

A port is a pair of terminals through which current may enter or leave a circuit network.

A port acts as access point to the network. In a port, the current entering one terminal leaves through the other terminal, so the net current entering the port equals to zero.

A network may have several ports.

- One-port network:resitor, capcitor or inductor, etc.

- Two-port network:transformer, BJT, or op amp, etc.

A two-port network has two port or two pairs of terminals.

Several sets of parameters are used to relate the voltages and currents in a network:

- Immitance parameters: impedance(z) parameters and admittance(y) parameters;

- Hybrid(h) parameters and inverse hybrid(g) parameters;

- Transmission parameters and inverse transmission(t) parameters;

- Scattering(s) parameters.

Impedance Parameters

When taking V1 and V2 as dependent parameters,we get

where the z terms are called impedance(z) parameters, or open-circuit impedance parameters.

Driving-point impedance: z11 and z22;

Transfer impedance: z12 and z21.

Reciprocal two-port network: when the points of excitation and response are exchanged, the transfer impedances remain the same(z12=z21).

- if a network is linear and has no dependant sources(e.g.,only with resistors, capacitors and inductors), it's linear.

The impedance parameters can be acquired by opening-circuting the input or output port.

When the output port is open-circuited(I2=0), we get

When the input port is open-circuited(I1=0), we get

Admittance Parameters

When taking I1 and I2 as dependent parameters,we get

where the y terms are called admittance(y) parameters, or short-circuit admittance parameters.

When the output port is short-circuited, we get

When the input port is short-circuited, we get

Transmission Parameters

When taking V1 and I1 as dependent parameters,we get

where ABCD are called transmission parameters.

When the output port is open-circuited, we get

When the output port is short-circuited, we get

Inverse Transmission Parameters(t Parameters)

When taking V2 and I2 as dependent parameters,we get

where abcd are called inverse transmission parameters.

When the input port is open-circuited, we get

When the input port is short-circuited, we get

Hybrid Parameters(h Parameters)

When taking V1 and I2 as dependent parameters,we get

where the h terms are called hybird(h) parameters.

When the output port is short-circuited, we get

When the input port is open-circuited, we get

Inverse Hybrid Parameters(g Parameters)

When taking I1 and V2 as dependent parameters,we get

where the h terms are called inverse hybird(g) parameters.

When the output port is open-circuited, we get

When the input port is short-circuited, we get


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