Figure P4-80 shows two circuits using the same transistor connected in different ways. The transistor has a \(\beta\) of 90 and a \(V\) \(\gamma\) of \(0.7 \mathrm{~V}\). Find the current gain of each circuit \(i_{\mathrm{C}} / i_{\mathrm{B}}\) for the common emitter and \(i_{\mathrm{C}} / i_{\mathrm{E}}\) for the common base configuration. Then compute the input resistance of each circuit, \(R_{\mathrm{IN}}=v_{\mathrm{IN}} / i\) \({ }_{\mathrm{N}}\). Check your answers using Multisim. Comment on the possible uses for each configuration. For the common base configuration, assume that the transistor is in the active mode and that KCL and the current gain relationships are valid, even though the currents are flowing opposite of the normal directions.

Transcribed Image Text:

iB +1 +1 100 5V ww RIN Common Emitter 100 ww 5V 1 www 1 ww ich iB RIN Common Base 5 V 5V