Solving for y parameters using a system of equations
hint: \$ Y_{11} = \frac{I_1}{V_1} \$ when you short-circuit \$ V_2 \$. This arises from \$ I_1 = V_1 Y_{11} + V_2 Y_{12} \$. The short-circuited \$ V_2 \$ forces the \$V_2 Y_{12} \$ term to zero.

The other equation that applies is \$ I_2 = V_1 Y_{21} + V_2 Y_{22} \$ .

Somehow, you just memorize these (they're burned into my non-volatile-memory). The other aid to memory is visualization of a current source in parallel with a conductance: one for input port and another for output port. Another aid to sanity-check your memory is to verify units. For Y-parameters, units must be in terms of conductance and/or susceptance....like a current divided by a voltage.







simulate this circuit &ndash; Schematic created using CircuitLab

You seem to be more familiar with Z-parameters. Here, units are resistance, and instead of current sources, you have two voltage sources, with series-resistors. Of course, you could solve the Z-parameter equations, then transform the four parameters into Y-parameters, but that's a bit round-about.