In a MOSFET, what does the threshold voltage (Vth) represent?

The correct answer is B: Minimum gate-source voltage needed to form a conducting channel. Threshold voltage (Vth) is the minimum gate-source voltage required to create an inversion layer and form a conducting channel between drain and source in a MOSFET.

In a differential amplifier using matched transistors, the Common Mode Rejection Ratio (CMRR) is primarily limited by:

The correct answer is A: Transistor mismatch and emitter resistance mismatch. CMRR depends on the matching of transistor parameters and passive components. Mismatches in emitter resistances and transistor characteristics directly degrade CMRR.

In a Colpitts oscillator, the feedback network consists of:

The correct answer is A: Two capacitors in series across the inductor. Colpitts oscillator uses capacitive voltage divider with two capacitors in series across an inductor for frequency-determining feedback.

In a MESFET (Metal-Semiconductor FET), compared to MOSFET:

The correct answer is D: All of the above are correct. MESFETs use Schottky metal-semiconductor junctions instead of oxide layers, resulting in lower gate capacitance, better high-frequency response (f_T/f_max higher), and simpler manufacturing process, especially in GaAs technology.

Which of the following is NOT a characteristic of ROM (Read-Only Memory)?

The correct answer is B: Programmable by user after manufacture. Standard ROM is programmed during manufacturing and cannot be reprogrammed by users. PROM, EPROM, and EEPROM allow user programming, but basic ROM does not