Jawaharlal Nehru Technological University Hyderabad B.Tech III VLSI DESIGN Previous Question Paper (February/March - 2022 - R18)

Transconductance (g_m) is a measure of the sensitivity of the drain current (I_D) to changes in the gate-source voltage (V_GS) while the drain-source voltage (V_DS) remains constant. It represents the gain of the MOSFET as a voltage-controlled current source.

In the saturation region, it is expressed as g_m = √(2μ_nC_ox(W/L)I_D). A higher transconductance indicates that a small change in input voltage results in a large change in output current, which is critical for high-gain amplifier design.

The figure of merit (ω_o), often referred to as the unity-gain bandwidth or transition frequency (f_T), represents the frequency at which the short-circuit current gain of a transistor drops to unity.

This parameter serves as a benchmark for the speed of a MOSFET. It indicates the upper frequency limit for the device's operation as an amplifier. A higher ω_T implies that the transistor can respond faster to high-frequency signals, making it a vital metric for high-speed digital and analog circuit performance.