Question

Comprehension

Instruction: Based on the following paragraph, answers the next five questions.

The scaling down of feature size generally leads to improved performance and it is important to understand the effect of scaling. Micro electronic technology may be characterized in terms of several indicators or figure of merit, such as minimum feature size, number of gates on one chip, power dissipation, maximum operating frequency etc. Many of these figure of merits (FOMs) can be improved by shrinking the dimensions of transistors, interconnections and separation between the features and by adjusting the doping levels and supply voltages. The most commonly used models are the constant electric field scaling model and constant voltage scaling model. The two scaling factors ‘α’ and ‘β’ are used. 

1. 1/α
2. 1/β 
3. α/β 
4. β/α 

Answer 1

Correct Answer - Option 2 : 1/β 

Saturation current (Id_ss) for a MOSFET is given by:

\({I_{dss}} = \frac{{{C_0}\mu }}{2}\times\frac{W}{L}\times{\left( {{V_{gs}} - {V_t}} \right)^2}\)

C_o = Capacitance of the insulating material

W and L are the dimensions of the insulating layer

V_gs = Threshold voltage

Both V_gs & V_t are scaled by (1/β)

Both W & L scaled by (1/α)

C₀ is scaled by ‘β’

∴ I_dss is scaled by:

\({I_{dss}} \Rightarrow β \times \frac{{1/\alpha }}{{1/\alpha }} \cdot {\left( {\frac{1}{β }} \right)^2}\)

⇒ 1/β