Discussion 2

2018/3/20

Outline

• Homework Issues • Review & Exercise • Op-Amp • Something New • Q&A

Quiz: Use Nodal Analysis to find the power developed by the

independent voltage source in the circuit.(20min)

Outline

• Homework Issues • Review & Exercise • Op-Amp • Something New • Q&A

Outline

• Homework Issues • Review & Exercise • Op-Amp • Something New • Q&A

What you have learned

1.q(t),i(t) 2.Current anaylsis： 1.KCL/KVL. 2.(super)Node/(super)Mesh. 3.Superposition, source transformation 4.Thevenin/Norton 5.Max Power Trans.

Review The steps are (1) Turn off all independent sources except one. Find the output (voltage or current) due to that active one. • Replace independent voltage source by short circuit, independent current source by open circuit. (2) Repeat step 1 for each of the other independent sources. (3) Find the total contribution by adding algebraically all the contributions due to the independent sources. Note that (1) Using superposition means applying one independent source at a time. (2) Dependent sources are left alone.

Outline

• Homework Issues • Review & Exercise • Op-Amp a little about it • Something New • Q&A

Example

Exercise(20 min)

Outline

• Homework Issues • Review & Exercise • Op-Amp • Something New

– 特勒根定理（Tellegen's theorem） – 互易定理

• Q&A

Tellegen‘s theorem （特勒根定理）

• (I1,I2,···,Ib),(U1,U2,···,Ub) are currents through & voltages across each branch.(currents and voltages follow passive sign convention) aI1*U1+I2*U2+···+Ib*Ub=0。

• passive sign convention(关联参考方向)

Tellegen's theorem

If two curcuits have the same graph (I1,I2…,Ib) ,(U1,U2,…,Ub) and(ǐ1,ǐ2,···,ǐb)、(ǔ1,ǔ2,···,ǔb) Then, ǐ1*U1+ǐ2*U2+···+ǐb*Ub=0 I1*ǔ1+I2*ǔ2+···+Ib*ǔb=0

Proof

Reciprocity Theorem(互易定理)

• 1.One independent source • 2.No dependent source • 3.only contains linear resistance

Proof

• Exercise : Use the new method to find I.(10min)

Outline

• Homework Issues • Review & Exercise • Something New • Q&A