The BJT in Fig. P6.56 is designed to operate within the FA region, where DvBE is small enough that we can ignore DQje. Moreover, R3 is made deliberately small so that DvBC is also small enough that we...

The BJT in Fig. P6.56 is designed to operate within the FA region, where DvBE is small enough that we can ignore DQje. Moreover, R3 is made deliberately small so that DvBC is also small enough that we can ignore DQjc. Under these conditions, Eq. (6.128) simplifi es as iB 5 QFyBF 1 dQFydt. (a) Given that in response to a 1-V input step the circuit yields an exponential transient with a 0.1-V magnitude, fi nd F, VOH, and VOL. (b) Suppose we now add a capacitor and adjust its value until the output transition becomes the perfect step shown in shaded form. If this occurs for C 5 2 pF, fi nd BF and F. (c) Sketch and label vO vs. time if C is lowered to 1 pF. (d) Repeat part (c) if C is raised to 3 pF. (d) Sketch and label vO vs. time if C 5 2 pF and R1 is removed from the circuit.