Question, for this below circuit :

Why is said that the test current i(t) flows in the parallel combination of r(pi) and R(E) ??

I understand both r(pi) and R(E) are parallel, but I cant see that the test current i(t) flows there ?

Or I missed out something ?

Please help.

Thanks

 

I feel rE is the Input resistance(base) and gmv1 is the output constant current source with its Output admittance r0(collector) and Re Terminal is Emitter of transistor equivalent circuit in common emitter configuration. Connecting a constant current source to the collector can be for a high dynamic Impedance load .

But input (base) being grounded there is no input(ac) Terminal. Hence please check the circuit diagram for any is missing circuit element.Also explain the purpose/functionional requirnment of this circuit

 

Question, for this below circuit :

Why is said that the test current i(t) flows in the parallel combination of r(pi) and R(E) ??

I understand both r(pi) and R(E) are parallel, but I cant see that the test current i(t) flows there ?

Or I missed out something ?

Please help.

Thanks

Well, where else can it flow? It has to split and flow through the internal current source and output resistance, combine back together, and then split again and flow through the input resistance and emitter resistance in order to return to the test source.

 

The current source i.t will go into the dependent source and r.o, then those currents will recombine to enter r.pi//R.E per KCL.