Zagazig University Course: Electronic Engineering 2
Faculty of Engineering Course code: ECE 123
Electronics and Comm. Dept. 2nd Semester 2024/2025
1st year ECE
Sheet 5
1.
a. Determine VDS for VGS = 0 V and ID = 6 mA
using the characteristics of Fig. 6.11.
b. Using the results of part (a), calculate the
resistance of the JFET for the region ID = 0
to 6 mA for VGS = 0 V.
c. Determine VDS for VGS = -1 V and ID = 3 mA.
d. Using the results of part (c), calculate the
resistance of the JFET for the region ID = 0
to 3 mA for VGS = -1 V.
e. Determine VDS for VGS = -2V and ID = 1.5 mA.
f. Using the results of part (e), calculate the
resistance of the JFET for the region ID = 0
to 1.5 mA for VGS = -2 V.
g. Defining the result of part (b) as ro, determine the resistance for VGS = -1 V using
and compare with the results of part (d).
h. Repeat part (g) for VGS = -2 V using the same equation, and compare the results with
part (f)
2. MOS technology is used to fabricate a capacitor, utilizing the gate metallization and
the substrate as the capacitor electrodes. Find the area required per 1-pF
capacitance for oxide thickness ranging from 2 nm to 10 nm. For a square plate
capacitor of 10 pF, what dimensions are needed?(𝜀0 = 8.854 × 10−12 𝐹⁄𝑚 , 𝜀𝑟 = 3.9)
3. Calculate the total charge stored in the channel of an NMOS transistor having C ox = 9
fF/μm2, L = 0.36 μm, and W = 3.6 μm, and operated at VOV = 0.2 V and VDS =0 V.
4. An NMOS transistor that is operated with a small vDS is found to exhibit a
resistance rDS. By what factor will rDS change in each of the following situations?
(a) VOV is doubled.
(b) The device is replaced with another fabricated in the same technology but with
double the width.
(c) The device is replaced with another fabricated in the same technology but with
both the width and length doubled.
(d) The device is replaced with another fabricated in a more advanced technology
for which the oxide thickness is halved and similarly for W and L (μn remains
unchanged).
Zagazig University Course: Electronic Engineering 2
Faculty of Engineering Course code: ECE 123
Electronics and Comm. Dept. 2nd Semester 2024/2025
1st year ECE
5. An n-channel MOS device in a technology for which oxide thickness is 4 nm, minimum
channel length is 0.18 μm, 𝑛𝐾′ =400 μA/V2, and Vt =0.5 V operates in the triode region,
with small vDS and with the gate–source voltage in the range 0V to +1.8 V. What
device width is needed to ensure that the minimum available resistance is 1 kΩ?
6. An NMOS transistor with kn = 4 mA/V2 and Vt = 0.5 V is operated with VGS = 1.0
V. At what value of VDS does the transistor enter the saturation region? What value
of ID is obtained in saturation?
7. Consider a CMOS process for which Lmin = 0.25 μm, tox = 6 nm, μn = 460 cm2/V· s,
and Vt = 0.5 V.
(a) Find Cox and 𝐾𝑛′ .
(b) For an NMOS transistor with W/L = 20 μm/0.25 μm, calculate the values of V OV ,
VGS, and VDSmin needed to operate the transistor in the saturation region with a dc
current ID
= 0.5 mA.
(c) For the device in (b), find the values of VOV and VGS required to cause the
device to operate as a 100Ω resistor for very small vDS.
8. For the circuit in Fig. 5.1, sketch iD versus vS for vS varying from 0 to VDD. Clearly
label your sketch.
9. Fig. 5.2 shows two NMOS transistors operating in saturation at equal VGS and VDS.
(a) If the two devices are matched except for a maximum possible mismatch in their
W/L ratios of 3%, what is the maximum resulting mismatch in the drain currents?
(b) If the two devices are matched except for a maximum possible mismatch in
their Vt values of 10 mV, what is the maximum resulting mismatch in the drain
currents? Assume that the nominal value of Vt is 0.6 V.
