6. (25%) Consider the voltage amplifier of Fig. 6 with a BJT device having β = 100 when it is biased in
the active region. The coupling capacitors C1 = C2 = C3 = 1 μF. The voltage supplies are 5 V and the
thermal voltage VT= 25.9 mV. If the transistor is specified to have fT = 700 MHz and Cμ = 1 pi. The
constant voltage drop 0.7 V approximation can be used for the turn-on of a p-n junction. In addition.
other resistances are also included in the Fig. 6. Please calculate (a)f1,f2,f3 (let f1 <f2<f3) values of the
low-frequcncy transfer function (b) the upper 3-dB frequcncy fHby using open-circuit time constants method if the ro and rx effect are neglected. (5%*3, 10%)
5. (25%) Consider the voltage amplifier of Fig. 5 with two BJT devices: Q1 and Q2, having β= 100
when they are biased in the active region. The coupling capacitors C can block DC component and pass
AC component. The voltage supplies are 10 V and the thermal voltage VT = 25.9 mV. The constant
voltage drop 0.7 V approximation can be used for the turn-on of a p-n junction. In addition, other
resistances are also included in the Fig. 5. Please come out the following parameters: (a) DC base voltage
of Q1:, (b) DC base voltage of Q2:
, (c) DC collector voltage of Q2:
. (d) overall AC voltage
gain
. (5%, 5%, 5%, 10%)
4. (15%) Consider the yoltage amplifier of Fig. 4 with a MOSFET specified to have Vt= 1.5 V,
(WIL) = 0.5 mArV2, andλ = 0.02
. The coupling capacitors C can block DC component and
pass AC component. Calculate (a) the small-signal voltage gain
(b) its input resistance
, and (O)
the largest allowable input signal. (5%*3)