Two identical nMOS transistors M_{1} and M_{2} are connected as shown below. The circuit is used as an amplifier with the input connected between G and S terminals and the output taken between D and S terminals. V_{bias} and VD are so adjusted that both transistors are in saturation. The transconductance of this combination is defined as $\style{font-family:'Times New Roman'}{g_m=\frac{\partial i_D}{\partial\nu_{GS}}}$ while the output resistance is $ r_o=\frac{\partial v_{{}_{DS}}}{\partial i_D} $ , where $\style{font-family:'Times New Roman'}{i_D}$ is the current flowing into the drain of M2 . Let $\style{font-family:'Times New Roman'}{g_{m1},\;g_{m2}}$ be the transconductances and $\style{font-family:'Times New Roman'}{r_{o1},\;r_{o2}}$ be the output resistances of transistors M_{1} and M_{2}, respectively
Which of the following statements about estimates for $\style{font-family:'Times New Roman'}{g_m}$ and $\style{font-family:'Times New Roman'}{r_o}$ is correct?
In a p-n junction diode at equilibrium, which one of the following statements is NOT TRUE?
A p-n step junction diode with a contact potential of 0.65 V has a depletion width of 1μm at equilibrium. The forward voltage (in volts, correct to two decimal places) at which this width reduces to 0.6 μm is _______.
There are two photolithography systems: one with light source of wavelength $ \lambda_1=156 $ nm (System 1) and another with light source of wavelength $ \lambda_2=325 $ nm (System 2). Both photolithography systems are otherwise identical. If the minimum feature sizes that can be realized using System1 and System2 are $ L_{min1} $ and $ L_{min2} $ respectively, the ratio $ L_{min1}/L_{min2} $ (correct to two decimal places) is__________.
Red (R), Green (G) and Blue (B) Light Emitting Diodes (LEDs) were fabricated using p-n junctions of three different inorganic semiconductors having different band-gaps. The builtin voltages of red, green and blue diodes are $V_R$, $V_G$ and $V_B$, respectively. Assume donor and acceptor doping to be the same ($N_A$ and $N_D$, respectively) in the p and n sides of all the three diodes.
Which one of the following relationships about the built-in voltages is TRUE?
In the circuit shown below, the $ \left(W/L\right) $ value for M_{2} is twice that for M_{1}. The two nMOS transistors are otherwise identical. The threshold voltage $V_T$ for both transistors is 1.0V. Note that $V_{GS}$ for M_{2} must be $>$1.0 V.
The voltage (in volts, accurate to two decimal places) at $V_x$ is _______.
A solar cell of area 1.0 cm^{2} , operating at 1.0 sun intensity, has a short circuit current of 20 mA, and an open circuit voltage of 0.65 V. Assuming room temperature operation and thermal equivalent voltage of 26 mV, the open circuit voltage (in volts, correct to two decimal places) at 0.2 sun intensity is _______.
A junction is made between $p^-$ Si with doping density $ N_{A1}=10^{15} $ cm^{-3} and $p$ Si with doping density $ N_{A2}=10^{17} $ cm^{-3} .
Given: Boltzmann constant $ k=1.38\times10^{-23}J\cdot K^{-1} $ , electronic charge $ q=1.6\times10^{-19} $ C. Assume 100% acceptor ionization.
At room temperature ($T$ = 300K), the magnitude of the built-in potential (in volts, correct to two decimal places) across this junction will be _________________.
A bar of Gallium Arsenide (GaAs) is doped with Silicon such that the Silicon atoms occupy Gallium and Arsenic sites in the GaAs crystal. Which one of the following statements is true?
An n^{+} -n Silicon device is fabricated with uniform and nono-degenerate donor doping concentration of N_{D1} =1 × 10^{18} cm^{-3} and N_{D2} =1 × 10^{15} cm^{-3} corresponding to the n^{+} and n regions respectively. At the operational temperature T, assume complete impurity ionization, kT/q=25mV, and intrinsic carrier concentration to be n_{i} = 1 × 10^{10} cm^{-3}. What is the magnitude of the built-in potential of this device?
The dependence of draft velocity of electrons field in a semiconductor is shown below. The semiconductor has a uniform electron concentration of n =1 × 10^{16} cm^{-3} and electronic charge q =1.6 × 10^{-19} C. If a bias of 5 V is applied across a 1 µm region of this semiconductor, the resulting current density in this region, in kA/cm^{2}, is____________.
As shown, a uniformly doped Silicon (Si) bar of length L=0.1 µm with a donor concentration N_{D}=10^{16 }cm^{-3} is illuminated at x=0 such that electron and hole pairs are generated at the rate of ${G}_{L}={G}_{LO}\left(1-\frac{x}{L}\right),0\le x\le L$, where G_{LO}=10^{17} cm^{-3} S^{-1}.Hole lifetime is 10^{-4}s, electronic charge q=1.6×10^{-19} C, hole diffusion coefficient D_{P}=1000 cm^{2}/s and low level injection condition prevails. Assuming a linearly decaying steady state excess hole concentration that goes to 0 at x=L, the magnitude of the diffusion current density at x=L/2, in A/cm^{2}, is__________.
As shown, two Silicon (Si) abrupt p-n junction diodes are fabricated with uniform donor doping concentration of N_{D1}=10^{14} cm^{-3} and N_{D2}=10^{16} cm^{-3} in the n-regions of the diodes, and uniform acceptor doping concentrations of N_{A1}=10^{14} cm^{-3} and N_{A2}=10^{16} cm^{-3} in the p-regions of the diodes, respectively. Assuming that the reverse bias voltage is » built-in potentials of the diodes, the ratio C_{ 2}/C_{1} of their reverse bias capacitances for the same applied reverse bias, is_________.
In the figure, D1 is a real silicon pn junction diode with a drop of 0.7 V under forward bias condition and D2 is a Zener diode with breakdown voltage of -6.8 V. The input V_{in}(t) is a periodic square wave of period T, whose one period is shown in the figure.
Assuming 10 $\tau$ << T, where $\tau$ is the time constant of the circuit, the maximum and minimum values of the waveform are respectively.
For a particular intensity of incident light on a silicon pn junction solar cell, the photocurrent density (J_{L}) is 2.5 mA/cm^{2} and the open-circuit voltage (V_{oc}) is 0.451 V. Consider thermal voltage (V_{T}) to be 25 mV. If the intensity of the incident lights is increased by 20 times, assuming that the temperature remain unchanged, V_{oc} (in volts) will be_________
An abrupt pn junction (location at x = 0) is uniformly doped on both p and n sides. The width of the depletion region is W and the electric field variation in the x-direction is E (x ). Which of the following figures represents the electric field profile near the pn junction?
Which of the above statements are INCORRECT?
What is the voltage V_{out} in the following circuit?
The figure below shows the doping distribution in a p-type semiconductor in log scale
The hole concentration at $t$=0 and the hole concentration at $t$=0.3 μs, respectively, are
The Ebers-Moll model of a BJT is valid
Assume that the diode in the figure has V_{on} = 0.7 V, but is otherwise ideal.
The magnitude of the current i_{2} (in mA) is equal to ________
A region of negative differential resistance is observed in the current voltage characteristics of a silicon PN junction if
A silicon sample is uniformly doped with donor type impurities with a concentration of 10^{16}/cm^{3}. The electron and hole mobilities in the sample are 1200 cm^{2}/V-s and 400 cm^{2}/V-s respectively. Assume complete ionization of impurities. The charge of an electron is 1.6 X 10^{-19} C. The resistivity of the sample (in $\mathrm{\Omega}$-cm) is _______.
In the circuit shown below, the Zener diode is ideal and the Zener voltage is 6 V. The output voltage V_{o} (in volts) is _______.
The built-in potential of an abrupt p-n junction is 0.75 V. If its junction capacitance (C_{J}) at a reverse bias (V_{R}) of 1.25 V is 5 pF, the value of C_{J} (in pF) when V_{R} = 7.25 V is_________.
A MOSFET in saturation has a drain current of 1 mA for V_{DS} =0.5 V. If the channel length modulation coefficient is 0.05 V^{-1}, the output resistance (in kΩ) of the MOSFET is_________
For a silicon diode with long P and N regions, the accepter and donor impurity concentrations are 1 x 10^{17} cm^{-3} and 1 x 10^{15} cm^{-3}, respectively. The lifetimes of electrons in P region and holes in N region are both 100 $\mathrm{\mu}$s. The electron and hole diffusion coefficients are 49 cm^{2}/s and 36 cm^{2}/s, respectively. Assume kT/q = 26 mV , the intrinsic carrier concentration is 1 X 10^{10} cm^{-3}, and q = 1.6 X 10^{-19} C. When a forward voltage of 208 mV is applied across the diode, the hole current density (in nA/cm^{2}) injected from P region to N region is _________.
For the NMOSFET in the circuit shown, the threshold voltage is V_{th ,} where V_{th }> 0. The source voltage V_{SS} is varied from 0 to V_{DD}. Neglecting the channel length modulation, the drain current I_{D} as a function of V_{SS} is represented by
An n-type silicon sample is uniformly illuminated with light which generates 10^{20} electron hole pairs per cm^{3} per second. The minority carrier lifetime in the sample is 1 μs. In the steady state, the hole concentration in the sample is approximately 10^{x}, where x is integer. The value of x is __________
A piece of silicon is doped uniformly with phosphorous with a doping concentration of 10^{16}/cm^{3}. The expected value of mobility versus doping concentration for silicon assuming full dopant ionization is shown below. The charge of an electron is 1.6X10^{-19} C. The conductivity (in S cm^{-1}) of the silicon sample at 300 K is ______.
A dc voltage of 10 V is applied across an n-type silicon bar having a rectangular cross-section and a length of 1 cm as shown in figure. The donor doping concentration N_{D} and the mobility of electrons ${\mu}_{n}$ are 10^{16} cm^{-3} and 1000 cm^{2} V^{-1}s^{-1} , respectively . The average time (in μs) taken by the electrons to move from one end of the bar to other end is________.
In a MOS capacitor with an oxide layer thickness of 10 nm, the maximum depletion layer thickness is 100 nm. The permittivities of the semiconductor and the oxide layer are ε_{s} and ε_{os }respectively. Assuming ε_{s}/ε_{ox}= 3, the ratio of the maximum capacitance to the minimum capacitance of this MOS capacitor is _____________.
The energy band diagram and the electron density profile n(x) in a semiconductor are shown in figures. Assume that $\mathrm{n}\left(\mathrm{x}\right)={10}^{15}{e}^{\left(\frac{qax}{kT}\right)}{\mathrm{cm}}^{-3}$ , with $\alpha $ = 0.1 V/cm and x expressed in cm. Given $\frac{kT}{q}$=0.026 V, $ D_n $ = 36cm^{2}s^{–1} , and $\frac{D}{\mu}=\frac{kT}{q}$ . The electron current density (in A/cm^{2}) at x = 0 is
Which one of the following process is preferred to form the gate dielectric (SiO_{2}) of MOSFETs ?
If the base width in a bipolar junction transistor is doubled, which one of the following statements will be TRUE?
The electric field profile in the depletion region of a p-n junction in equilibrium is shown in the figure. Which one of the following statements is NOT TRUE?
The current in an enhancement mode NMOS transistor biased in saturation mode was measured to be 1 mA at a drain-source voltage of 5 V. When the drain-source voltage was increased to 6 V while keeping gate-source voltage same, the drain current increased to 1.02 mA. Assume that drain to source saturation voltage is much smaller than the applied drain-source voltage. The channel length modulation parameter $\lambda $ (in V^{-1}) is ______.
An npn BJT having reverse saturation current I_{s} = 10^{-15} A is biased in the forward active region with V_{BE} = 700 mV. The thermal voltage (V_{T}) is 25 mV and the current gain ($\beta $) may vary from 50 to 150 due to manufacturing variations. The maximum emitter current (in μA) is _____.
When the optical power incident on a photodiode is 10µW and the responsivity is 0.8 A/W, the photocurrent generated (in µA) is ________.
In the figure, assume that the forward voltage drops of the PN diode D_{1} and Schottky diode D_{2} are 0.7 V and 0.3 V, respectively. If ON denotes conducting state of the diode and OFF denotes nonconducting state of the diode, then in the circuit,
If fixed positive charges are present in the gate oxide of an n-channel enhancement type MOSFET, it will lead to
A BJT is biased in forward active mode. Assume V_{BE} = 0.7 V, kT/q = 25 mV and reverse saturation I_{S}=10^{-13} A. The transconductance of the BJT (in mA/V) is________.
The doping concentrations on the p-side and n-side of a silicon diode are 1×10^{16}CM^{-3} m and 1×10^{17}CM^{-3} m , respectively. A forward bias of 0.3 V is applied to the diode. At T = 300 K, the intrinsic carrier concentration of silicon n_{i}=1.5×10^{10}CM^{-3} m and $\frac{kT}{q}=26$ mV. The electron concentration at the edge of the depletion region on the p-side is ___________.
A depletion type N-channel MOSFET is biased in its linear region for use as a voltage controlled resistor. Assume threshold voltage V_{TH}= -0.5 V, V_{GS}= 2.0 V, V_{DS}= 5 V, W/L = 100, C_{OX}= 10^{-8} F/ Cm^{2} and μ_{n}= 800 Cm^{2} /V-s. The value of the resistance of the voltage Controlle resistor (in Ω) is_____.
A silicon bar is doped with donor impurities N_{D} = 2.25 x 10^{15} atoms / cm^{3}. Given the intrinsic carrier concentration of silicon at T = 300 K is n_{i} = 1.5 x 10^{10} cm^{-3}. Assuming complete impurity ionization, the equilibrium electron and hole concentrations are
An increase in the base recombination of a BJT will increase
In CMOS technology, shallow P-well or N-well regions can be formed using
Assume electronic charge q = 1.6×10^{-19} C, kT/q = 25 mV and electron mobility μ_{n} = 1000 cm^{2}/V-s. If the concentration gradient of electrons injected into a P-type silicon sample is 1×10^{21}/cm^{4}, the magnitude of electron diffusion current density (in A/cm^{2}) is _________.
Consider an abrupt PN junction (at T = 300 K) shown in the figure. The depletion region width X_{n} on the N-side of the junction is 0.2 μm and the permittivity of silicon (ε_{si}) is 1.044×10^{-12} F/cm. At the junction, the approximate value of the peak electric field (in kV/cm) is _________.
When a silicon diode having a doping concentration of N_{A} = 9 × 10^{16} cm^{-3} on p-side and N_{D} = 1 × 10^{16} cm^{-3} on n-side is reverse biased, the total depletion width is found to be 3 μm. Given that the permittivity of silicon is 1.04 × 10^{–12} F/cm, the depletion width on the p-side and the maximum electric field in the depletion region, respectively, are
The diode in the circuit shown has V_{on} = 0.7 Volts but is ideal otherwise. If V_{i} = 5sin(ωt )Volts, the minimum and maximum values of V_{o} (in Volts) are, respectively,
For the n-channel MOS transistor shown in the figure, the threshold voltage V_{Th} is 0.8 V. Neglect channel length modulation effects. When the drain voltage V_{D}=1.6 V, the drain current I_{D} was found to be 0.5 mA. If V_{D} is adjusted to be 2 _{V} by changing the values of R and V_{DD}, the new value of I_{D} (in mA) is
For the MOSFETs shown in the figure, the threshold voltage |V_{t}| = 2 V and
$K=\frac{1}{2}\mu {C}_{ox}\left(\frac{W}{L}\right)=0.1\mathrm{mA}/{\mathrm{V}}^{2}$ The value of I_{D} (in mA) is _______ .
In MOSFET fabrication, the channel length is defined during the process of
A thin P-type silicon sample is uniformly illuminated with light which generates excess carriers. The recombination rate is directly proportional to
At T = 300 K, the hole mobility of a semiconductor ${\mu}_{p}=500c{m}^{2}/\mathrm{V}-\mathrm{s}$ and $\frac{kT}{q}=26\mathrm{mV}$ The hole diffusion constant D_{p} in cm^{2}/s is ________
The donor and accepter impurities in an abrupt junction silicon diode are 1 x 10^{16} cm^{-3} and 5 x 10^{18} cm^{-3}, respectively. Assume that the intrinsic carrier concentration in silicon n_{i} = 1.5 x 10^{10} cm^{-3} at 300 K, $\frac{kT}{q}$ = 26 mV and the permittivity of silicon ${\mathit{\in}}_{si}$ =1.04×10^{−12}F/cm. The built-in potential and the depletion width of the diode under thermal equilibrium conditions, respectively, are
The slope of the I_{D} vs.V_{GS} curve of an n-channel MOSFET in linear regime is 10^{−3}Ω^{−1} at V_{DS}=0.1 V. For the same device, neglecting channel length modulation, the slope of the $\sqrt{{I}_{D}}$ vs. V_{GS} curve (in $\raisebox{1ex}{$\sqrt{A}$}\!\left/ \!\raisebox{-1ex}{$V$}\right.$) under saturation regime is approximately _________.
An ideal MOS capacitor has boron doping-concentration of 10^{15} cm^{-3} in the substrate. When a gate voltage is applied, a depletion region of width 0.5 μm is formed with a surface (channel) potential of 0.2 V. Given that ε_{0} = 8.854 × 10^{-14} F/cm and the relative permittivities of silicon and silicon dioxide are 12 and 4, respectively, the peak electric field (in V/μm) in the oxide region is _____________.
For the MOSFET M_{1} shown in the figure, assume W/L = 2, V_{DD} = 2.0 V,${\mu}_{n}{C}_{ox}=100\mu A/{V}^{2}$ and V_{TH} = 0.5 V. The transistor M_{1} switches from saturation region to linear region when V_{in} (in Volts) is__________.
At T = 300 K, the band gap and the intrinsic carrier concentration of GaAs are 1.42 eV and 10^{6} cm^{-3}, respectively. In order to generate electron hole pairs in GaAs, which one of the wavelength (λ_{C}) ranges of incident radiation, is most suitable? (Given that: Plank’s constant is 6.62 × 10^{-34} J-s, velocity of light is 3 × 10^{10} cm/s and charge of electron is 1.6 × 10^{-19} C)
In the figure, ln (ρ_{i}) is plotted as a function of 1/T, where ρ_{i} is the intrinsic resistivity of silicon, T is the temperature, and the plot is almost linear.
The slope of the line can be used to estimate
The cut-off wavelength (in μm) of light that can be used for intrinsic excitation of a semiconductor material of bandgap E_{g}= 1.1 eV is ________
Consider a silicon sample doped with N_{D} = 1×10^{15}/cm^{3} donor atoms. Assume that the intrinsic carrier concentration n_{i} = 1.5×10^{10}/cm^{3}. If the sample is additionally doped with N_{A} = 1×10^{18}/cm^{3} acceptor atoms, the approximate number of electrons/cm^{3} in the sample, at T=300 K, will be ______.
Consider two BJTs biased at the same collector current with area A_{1} = 0.2 μm × 0.2 μm and A_{2} = 300 μm × 300 μm. Assuming that all other device parameters are identical, kT/q = 26 mV, the intrinsic carrier concentration is 1 × 10^{10} cm^{-3}, and q = 1.6 × 10^{-19} C, the difference between the base-emitter voltages (in mV) of the two BJTs (i.e., V_{BE1} – V_{BE2}) is _____.
An N-type semiconductor having uniform doping is biased as shown in the figure.
If E_{C} is the lowest energy level of the conduction band, E_{V} is the highest energy level of the valance band and E_{F} is the Fermi level, which one of the following represents the energy band diagram for the biased N-type semiconductor?
A BJT in a common-base configuration is used to amplify a signal received by a 50 Ω antenna. Assume kT/q = 25 mV. The value of the collector bias current (in mA) required to match the input impedance of the amplifier to the impedance of the antenna is________.
In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is
In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces
The return loss of a device is found to be 20 dB. The voltage standing wave ratio (VSWR) and magnitude of reflection coefficient are respectively
The i-v characteristics of the diode in the circuit given below are
$i=\left\{\begin{array}{ll}\frac{v-0.7}{500}A,& v\ge 0.7v\\ 0A,& v0.7v\end{array}\right.$
The current in the circuit is
The source of a silicon (n_{i} = 10^{10} per cm^{3}) n-channel MOS transistor has an area of 1 sq μm and a depth of 1 μm. If the dopant density in the source is 10^{19}/cm^{3}, the number of holes in the source region with the above volume is approximately
In the three dimensional view of a silicon n-channel MOS transistor shown below, $\delta $= 20 nm. The transistor is of width 1 $\mu $m. The depletion width formed at every p-n junction is 10 nm. The relative permittivities of Si and SiO_{2}, respectively, are 11.7 and 3.9, and ${\epsilon}_{0}$ = 8.9 $\times $ 10^{-12} F/m.
The gate-source overlap capacitance is approximately
The source-body junction capacitance is approximately
A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10^{o}C, the forward bias voltage across the PN junction
A Zener diode, when used in voltage stabilization circuits, is biased in