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 ϵr = 11.8. If the intrinsic concentration is 1010/cm3. The doping density ND is _____ × 1017/cm3 (KT = 0.026 V)
The doping density is given by:
= 1010 e(0.437/0.026)
= 1.99 × 1017
The figure shows MOS capacitor variation with applied gate voltage for n-type body/substrate.
The flat band voltage is:
The insulator capacitance Ci of an ideal MOS capacitor with 10-nm gate oxide (εr = 3.9) on p-type Si with Na = 1016 cm-3 is ________ × 10-7 F/cm2
The insulator capacitance is the capacitance under strong accumulation
= 3.453 × 10-7 F/cm2
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 ϵs = permittivity of semiconductor, ϵox = permittivity of oxide and
Given, tox = 10 nm, d = 100 nm
Cmin = series combination of Cox and Cdep
= 0.09 ϵA
The mobility of hole is 0.4 times the mobility of electron. What must be the ratio of width of n-channel to p-channel MOSFET if they are to have equal drain currents when operated in saturation mode with same magnitude of overdrive voltage:
ID-n = ID-p
μn Wn = μp Wp
The circuit shown uses an NMOS transistor to implement a current source. For the transistor VTN = 1V and =12.5 uA/V2. The required value of VGS to get IDC = 25 μA and corresponding compliance voltage is:
2 = (VGS - 1)2‑
VGS = √2 + 1 = 2.414 V
To function as a current source, the transistor must be in saturation or VDS > VDS (sat).
VDS (sat) = VGS - VTN
= 2.414 – 1
Hence compliance voltage = 1.414 V.
Compliance voltage is the minimum voltage required to achieve the desired performance.
The output resistance R0 of the NMOS circuit if ID = 0.5 mA, λ = 0.02 V-1, _____ kilo ohms.
The small signal model with a test voltage Vx is shown.
The output resistance is given by:
From the circuit, Vgs = Vx
For a MOSFET with gate plate area 0.5 × 10-2 cm2 and oxide layer thickness 80 nm, the value of MOS capacitance and its break down voltage are: (assume relative di-electric constant of sio2, ϵr = 4 and ϵ0 = 8.854 × 10-14 F/cm and dielectric strength of sio2 film is 5 × 106 V/cm)
Given gate plate area, which is also MOS capacitor area A = 0.5 × 10-2cm2
Oxide layer thickness tox = 80 nm
The value of MOS capacitance:
= 0.22 μF
Dielectric breakdown happens of field greater than dielectric strength (5 × 106 V/cm)
V = 5 × 108 × 80 × 10-9 V = 40V
In the circuit shown in Figure, Transistors are characterized by and λ = 0
The output voltage V0 is _______V
Gate is connected to drain Both Transistor are in Saturation.
For M1 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