EE114 Autumn 09/10
R. Dutton
Page 1 of 6
HOMEWORK #6
(Due: Friday, December 4, 2009, noon PT)
In this problem set, please refer to EE114 technology device parameters from
lecture 7 slide 12 whenever you need device constants in your calculations, except
where you are told to explicitly ignore terms.
1. Consider the amplifier circuit shown below (i.e. somewhat similar to the second stage
architecture from Lecture 25, Slide 18). All NMOS and PMOS devices are assumed to have
identical W/L values and operate in the saturation region. Neglect the backgate effect
(Gamma=0) for all transistors and consider output conductance (symbolically) only for small
signal ac impedance calculations.
a) Assuming that I(M
1A
)=I(M
2A
)=75
A and MagicBattery1=1.1V, determine the gate overdrive
(V
OV
) of the NMOS devices as well as the minimum dc output voltage level (numerical
value) for which M
2B
remains saturated.
b) Determine the range of voltages for which MagicBattery2 allows the circuit to work properly
(keeping all devices saturated).
Here we assume that the upper current source has a minimum
voltage across it of 200mV. [Note: in a real circuit commonmode feedback would be needed
to keep the operating point stable.
This issue is not addressed or required for you to solve the
problem, but circuit would never work in SPICE or a real application as shown]
c) Determine symbolically
the ac smallsignal resistances R
o2
and R
o1
as shown. Simplify your
analysis by assuming g
m
r
o
>> 1, stating clearly where you use the approximation.
Transistor Parameters
:
M1=M2
: W/L=48
KP=50
A/V
2
, V
t
=0.5V,
(Gamma)=0
(g
mNMOS
, r
oNMOS
)
M3
: W/L=48
KP=25
A/V
2
, V
t
=0.5V,
(Gamma)=0
(g
mPMOS
, r
oPMOS
)
I
BIAS
=150
A
M
2A
V
DD
=3V
v
i
MagicBattery1
MagicBattery2
M
1A
M
1B
M
2B
R
o1
R
o2
v
min
=0.2V
M
3a
M
3b
v
i
(dm)
v
o
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 Fall '08
 MURMANN
 Voltage source, Electrical parameters, Hendrik Wade Bode, R. Dutton

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