I have a circuit as shown below


simulate this circuit – Schematic created using CircuitLab

Where R1, R2 are resistors. jX1 and jX3 are reactants, and jB2 is admittance. That being said, I'm not sure how to find Zin (Total input impedance). I have 2 theories:

  1. Convert jB2 to impedance by taking its inverse (Z = 1/Y) and find total impedance: $$ Zin = R1 + jX1 + ((R2 + jX3)||jB2) $$
  2. Just ignore the admittance in this calculation since it's not an impedance $$ Zin = R1 + jX1 + jx3 + R2 $$

I'm not sure which one is correct. Both seem to be correct to me. Any help would be appreciated!

  • 2
    \$\begingroup\$ For finding the total input impedance one must know where the input is (input nodes). \$\endgroup\$
    – LvW
    May 5, 2017 at 13:04

1 Answer 1


I'll convert the admittance into impedance first then treat all components as resistors but always follow the correct math with the imaginary part (j). I think that's the easiest way of doing this.


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