Y-Parameters Calculation

Y-Parameters of Ladder Network

Definition:

I1 = Y11·V1 + Y12·V2
I2 = Y21·V1 + Y22·V2

Step 1: Find Y11 and Y21 (V2 = 0, Output Shorted)

• Output short → 20Ω bypassed
• 8Ω directly to ground
• Parallel at node A: (8 × 10)/(18) = 4.44Ω
• Total input: Z = 2 + 4.44 = 6.44Ω
• Y11 = 1 / 6.44 ≈ 0.155 S

Y21 ≈ -0.086 S

Step 2: Find Y22 and Y12 (V1 = 0, Input Shorted)

• Input short simplifies network
• Y22 ≈ 0.07 S
• Y12 ≈ -0.03 S

Final Y Matrix

[ 0.155    -0.03
  -0.086    0.07 ] S

ABCD Shortcut Method

If ABCD parameters are known:

T = [ A   B
C   D ]

Y11 = D / B
Y21 = −1 / B
Y22 = A / B
Y12 = (BC − AD) / B

Using:

A = 1.78, B = 25.84, C = 0.195, D = 3.3

Y11 = 0.1277 S
Y12 = −0.0323 S
Y21 = −0.0387 S
Y22 = 0.0689 S

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