Amin’s Guidelines for Lab Report #5
Introduction
State the objective(s)/purpose(s) for this lab
Journal
(a)
Derive an analytical expression for the small-signal voltage gain (i.e. av 
vout
) of
vin
the circuit depicted in Figure 1.
(b)
Using the MOS parameters provided in the pre-lab, determine (by hand) VIN that
results in VOUT = 2.5V for the circuit in Figure 1. In what region of operation is the
NMOS transistor at such a bias point?
(c)
Compute (by hand) the values of gm and ro for the NMOS transistor in Figure 1 at the
bias point VOUT = 2.5V. Again, assume the MOS parameters provided in the pre-lab.
Next, compute a numerical value for the small-signal voltage gain using the
expression derived in part (a).
(d)
Derive an analytical expression for the input and output resistances for the amplifier
depicted in Figure 1. What are the values of these resistances at the bias point VOUT =
2.5V? Verify these results in SPICE using the .TF statement.
(e)
Compute (by hand) the range of vOUT for which all devices remain in saturation.
(f)
Using SPICE, obtain the VTC for the circuit depicted in Figure 1. Overlay on this
plot the VTC obtained for the same circuit using the parameter analyzer. Indicate (or
specify) the range for VIN over which all devices remain in saturation.
(g)
Using SPICE, obtain a plot for the small-signal gain versus VOUT for the circuit
depicted in Figure 1. Overlay on this plot the small-signal gain versus VOUT obtained
for the same circuit using the parameter analyzer. Indicate (or specify) the range for
VOUT over which all devices remain in saturation.
(h)
From the plot in (g), find the output voltage range for which the amplifier’s gain is
greater than 50% of its maximum. On what side of the maximum does the gain
decrease sharply?
(i)
Determine V1 and V2 as described in sections 3.3 and 3.4 of the lab manual. Also,
answer all of the questions in these two sections.
(j)
Repeat all of the above with RD in Figure 1 now equaling 100kΩ.
(k)
Specify the small-signal gain and output resistance observed for section 4.
Conclusions
(a) Comment on the differences in the small-signal gain between RD = 5kΩ and RD = 100kΩ.
Comment on the differences in V1/V2 between RD = 5kΩ and RD = 100kΩ (see (i) in the
Journal). Does there seem to be a tradeoff here?
(b) Compare/comment on the discrepancies between the small-signal gain and output
resistance computed by hand, SPICE, and observed in the lab.
(c) For maximum gain, does the operating region of the transistor matter? If so, what is the
desired operating region for the transistor? (see (h) in the Journal)