# Is this hybrid pi model of a BJT unileteral or bileteral?

In introductory texts, the BJT is said to be a unilateral device. I think it means that the base current is only a function of Vbe; and Vbe is not function of Vce and Ic(?) Is the following BJT model unileteral or bileteral?

In other words, according to the above model, is the base current or Vbe function of any output parameters like Vce or Ic?

• That's a small-signal version (using derivatives) and is useless for large-scale results. The large-scale models (lacking Early Effect $r_o$, though) are here. If you focus on active mode and take the deriviative, you'll get the linearized hybrid-$\pi$. But it's only valid close-by around a specific operating point. – jonk Mar 2 at 22:03
• I see but Im asking only about the approximate model in the question. Is that model unileteral? – pnatk Mar 3 at 0:55
• Well, if I felt I understood the exact question I might try and offer a suggestion. But I don't feel as though I do. So I'm not sure which direction to head. That said, do you understand how a current mirror works? – jonk Mar 3 at 1:45