1. Show that the minimum conductivity of an extrinsic silicon
sample occurs when it is slightly p-type. Calculate the electron
and hole concentrations when the conductivity is minimum.
Given that µn = 1350 cm2/V-sec, µp = 450 cm2/V-sec, and the
intrinsic carrier concentration, ni = 1.5x1010 cm-3.
electron concentration = 0.866 x 1010 cm-3.
2. In the common emitter amplifier shown in the figure below, the
transistor has a forward current gain of 100, and a base-emitter
voltage of VBE = 0.6 volts. Assume ICO to be negligible.
Choose value of R1 and R3 such that the transistor has a
collector of 1 mA and a collector to emitter voltage of 2.5 volts.
Ans : R1 = 41 K and R3 = 2.2 K
3. A typical CMOS interval has the transfer characteristics (VTC)
(VO-Vin) as shown in the figure below. Evaluate the value of
the inverter threshold VINV, which is the value of the input
at which VO falls abruptly by ∆Vo = VTn + VTp.