In logic applications of the BJT inverter, it is desirable that the VTC be centered near the middle of the vI range. The VTC of the simple inverter of top, is centered about 1 V, but it can easily be...

In logic applications of the BJT inverter, it is desirable that the VTC be centered near the middle of the vI range. The VTC of the simple inverter of top, is centered about 1 V, but it can easily be shifted to the right by connecting an additional resistance RBE across the B-E junction, as depicted in Fig. P2.35. (a) Show that we now have vI 5 RBiB 1 (1 1 RBy RBE)vBE. (b) Assuming the same BJT parameters as in Fig. 2.32 (F 5 100 and Is 5 2 fA), obtain an input-output relationship of the type of Eq. (2.38), of course suitably modifi ed to refl ect the presence of RBE. (c) Find the voltage VI needed to bias the BJT at VO 5 2.5 V. (d) What is the voltage gain a there? How does it compare with that of Example 2.10? Justify any difference.