Circuit Coupling Model Containing Equivalent Eddy Current ...
ECE2280 Homework #1 Fall 2011ece3110/ECE3110F11_HW1sol.pdfFor the circuit shown below, draw the AC...
Transcript of ECE2280 Homework #1 Fall 2011ece3110/ECE3110F11_HW1sol.pdfFor the circuit shown below, draw the AC...
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ECE2280 Homework #1 Fall 2011
1. Use: ignore ro, |VBE|=0.7, ββββ=100
VI = 20+0.001sin(20t) For DC analysis, assume that the capacitors are open
(a) Solve for the DC currents:
a. IB
b. IE
c. IC
(b) Solve for the DC voltages:
a. VB
b. VE
c. Vo
(c) Prove or disprove the region of operation you assumed to
solve for your answers in (a) and (b)?
Vo
Rout
VI
IE
VB
VE
IB
IC
Vx 0≠
+
-
10k
2k C4
100mQ1
Q2N3904
I1
1m
8V
1k
900
10V
6V
C3
100m
100
6kΩ
4kΩ
6.7V
100Ω
2V
1mA 100Ω
4kΩ
16V
4kΩ
2
~ Vsig
gm2Vπ2
3kΩ
gm1Vπ1
+
Vπ1
- Rin
1kΩ
Rout
Vo 2kΩ
2kΩ
100Ω
rπ1
rπ2
+
Vπ2
-
2k
6kΩ
4kΩ 4kΩ 3kΩ
2. Use: ignore ro, |VBE|=0.7, ββββ=100
VI = 5+0.001sin(500t)
rππππ1=2, 000 gm2=50mA/V, and IB2=12.5µµµµA
For the following hybrid-π equivalent circuit below, find the following values:
(a) Rin (input resistance –ignore only the input source, Vsig and include all resistors at the base)
(b) Rout (output resistance-include all resistors at the collectorno load is connected)
(c) midband gain, Vsig
Vo
3. For the circuit shown below, draw
Make sure that everything is labeled in terms of the transistor number. (e.g. g
transistors. vsig=0.001sin(10t) AC. Assume all capacitors are shorted.
vsig
+15V
R4
R
3
draw the AC small-signal equivalent circuit(use hybrid
Make sure that everything is labeled in terms of the transistor number. (e.g. gm1, vπ2, etc.).
=0.001sin(10t) AC. Assume all capacitors are shorted.
+15V
-15V
R6
signal equivalent circuit(use hybrid-π or model T).
, etc.). Include ro for all
4
4. Use:
Vt=2V
kn’(W/L)=4mA/V2
λλλλ=0
VI = 10+0.002sin(20t) For DC analysis, assume that
the capacitors act as open
(d) Solve for the DC currents:
a. I1
b. ID
c. IS
(e) Solve for the DC voltages:
a. VG
b. VS
c. Vo
(f) Verify that the transistor is saturated.
(g) State the DC bias point.
(h) Assuming that the transistor amplification Vo/VI = -7V/V. What is the total (AC and DC)
instantaneous output for Vo (VI value stated above).
~
3C
VI +
+
2k 3k
4V
2k
1k
4C oV
GV
SV
NMOS 100m
1m
+9V
DI
SI
1I
inR
outR
500Ω
500Ω
1.7V
5
5. Use: Vt=2V
kn’(W/L)=3mA/V2
Vsig is an AC source
Transistor 1 has DC values: VGS=4V, ID=6mA
Transistor 2 has DC values: VGS=5.3V, ID=16.7mA
λ=0 (for all transistors)
For the following hybrid-π equivalent circuit, find the following values:
(a) Rin (input resistance –ignore the input source, Vsig)
(b) Rout (output resistance-ignore RLno load is connected)
(c) midband gain, Vsig
Vo
inR
~ gs1vgs2v sigv
outR
LR 1k= Ω
2kΩ
m1 gs1g v 1kΩ2MΩ
3MΩ
1kΩ
+ +
1kΩ
oV m2 gs2g v
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6. For the circuit shown below, draw the AC small-signal equivalent circuit(use hybrid-π or model T).
Make sure that everything is labeled in terms of the transistor number. (e.g. gm1, vgs2, etc.). λ=0 for all
transistors. vsig=0.005sin(20t) AC. Assume all capacitors are closed for the AC circuit.
~
3C
sigV
+15V
1mA
5V
2R
8R
1R 6R
NMOS
1V
100m
+10V 3R
10R
9R
5R
4R
+
+
NMOS
7R
-15V
1C
2M
1M
10m
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7 (a) Design the cascode amplifier with 2 PMOS transistors for the current source(as shown in class or Fig.
7.11) at a current of 0.1mA with all devices operating at |Vov|=0.25V. All devices have |VA|=4V. Find gm1,
the output resistance of the amplifier, Ron, the output resistance of the current source, Rop, the overall output
resistance, Rout, and the voltage gain, Av.
(b) Use the same circuit with the following DC voltages: VIn=0.8V, VG2=1.2V, VG3=1.3V, VG4=1.7V, and
VDD=2.5V. If all devices are matched, that is kn1= kn2= kp3= kp4, and have equal |Vt|=0.5V, what is the
overdrive voltage at which the four transistors are operating(Note this is different from part (a))? What is the
allowable voltage range at the output?
(a)
(b)
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8. Design the cascode amplifier that utilizes 2 PMOS transistors for the current source to have the following
specifications: gm1=2mA/V, and Av=-200V/V. Assume that the available fabrication process has
V’A=5V/µm for both NMOS and PMOS devices and that µnCox= 4µpCox=400µA/V
2 . Use the same channel
length L for all devices and operate all four devices at |Vov|=0.2V. Determine the required channel length L,
the bias current I, and the W/L ratio for each of four transistors. Assume that suitable bias voltages have been
chosen, and neglect the Early effect in determining the W/L ratios.
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9. A cascode current source formed of two pnp transistors for which β=50 and VA=5V supplies a current of
0.5mA. What is the output resistance?
10. The figures below show four possible realizations of the folded cascode amplifier. Assume that the BJTs
have β=100 and that both the BJTs and the MOSFETs have |VA|=5V. Let I=100µA, and assume that the
MOSFETs are operating at |VOV|=0.2V. Assume the current sources are ideal. For each circuit determine,
Rin, Rout, and the gain Vo/VI. Comment on your results.
(a)
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(b)
(c)
(d)