The figure shows the VTC characteristics of an NMOS inverter with three varying resistive loads (R).
The correct statement is:
Assume that the zero for electrostatic potential is in the semiconductor bulk at large x and that there is no metal semiconductor work function difference. The relative dielectric constant for the oxide is ϵ_{r} = 11.8. If the intrinsic concentration is 10^{10}/cm^{3}. The doping density N_{D} is _____ × 10^{17}/cm^{3} (KT = 0.026 V)
The doping density is given by:
= 10^{10} e^{(0.437/0.026)}
= 1.99 × 10^{17}
The figure shows MOS capacitor variation with applied gate voltage for ntype body/substrate.
The flat band voltage is:
The insulator capacitance C_{i} of an ideal MOS capacitor with 10nm gate oxide (ε_{r} = 3.9) on ptype Si with N_{a} = 10^{16} cm^{3} is ________ × 10^{7} F/cm^{2}
The insulator capacitance is the capacitance under strong accumulation
= 3.453 × 10^{7} F/cm^{2}
Which of the following curves represents the correct C – V characteristics of an NMOS transistor having an oxide layer thickness of 10 nm and a maximum depletion thickness of 100 nm. [Assume ϵ_{s} = permittivity of semiconductor, ϵ_{ox} = permittivity of oxide and
Given, t_{ox }= 10 nm, d = 100 nm
C_{min} = series combination of C_{ox} and C_{dep
}
= 0.09 ϵA
The mobility of hole is 0.4 times the mobility of electron. What must be the ratio of width of nchannel to pchannel MOSFET if they are to have equal drain currents when operated in saturation mode with same magnitude of overdrive voltage:
I_{Dn} = I_{Dp
}
μ_{n} W_{n} = μ_{p} W_{p
}
The circuit shown uses an NMOS transistor to implement a current source. For the transistor V_{TN} = 1V and =12.5 uA/V^{2}. The required value of V_{GS} to get I_{DC} = 25 μA and corresponding compliance voltage is:
2 = (V_{GS}  1)^{2‑}
V_{GS} = √2 + 1 = 2.414 V
To function as a current source, the transistor must be in saturation or V_{DS} > V_{DS} (sat).
V_{DS} (sat) = V_{GS}  V_{TN}
= 2.414 – 1
= 1.414.
Hence compliance voltage = 1.414 V.
Compliance voltage is the minimum voltage required to achieve the desired performance.
The output resistance R_{0} of the NMOS circuit if I_{D} = 0.5 mA, λ = 0.02 V^{1}, _____ kilo ohms.
The small signal model with a test voltage V_{x} is shown.
The output resistance is given by:
From the circuit, V_{gs} = V_{x}
Applying KCL:
For a MOSFET with gate plate area 0.5 × 10^{2 }cm^{2} and oxide layer thickness 80 nm, the value of MOS capacitance and its break down voltage are: (assume relative dielectric constant of sio_{2}, ϵ_{r} = 4 and ϵ_{0} = 8.854 × 10^{14} F/cm and dielectric strength of sio_{2} film is 5 × 10^{6} V/cm)
Given gate plate area, which is also MOS capacitor area A = 0.5 × 10^{2}cm^{2}
Oxide layer thickness t_{ox} = 80 nm
The value of MOS capacitance:
= 0.22 μF
Dielectric breakdown happens of field greater than dielectric strength (5 × 10^{6} V/cm)
V = 5 × 10^{8} × 80 × 10^{9} V = 40V
In the circuit shown in Figure, Transistors are characterized by and λ = 0
The output voltage V_{0} is _______V
Gate is connected to drain Both Transistor are in Saturation.
For M_{1} Transistor:
⇒ (V  8)^{2} = 4
⇒ V  8 = ± 2
(i) Taking +ve, V = 8 + 2 = 10 V (Not Possible)
(ii) Taking ve, V = 8  2 = 6 V
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