Electronics (ECE) - MCQ Practice Questions

Common-gate configuration presents low input impedance (≈ 1/gm) and high output impedance. It provides good isolation and is useful for impedance matching.

Hysteresis voltage ΔV = 2Vsat × R1/(R1+R2), where Vsat is op-amp output saturation voltage. It depends on both the feedback resistor ratio and the op-amp's output swing (supply voltage).

For a summing amplifier, Vout = -Rf(V1/R1 + V2/R2 + ... + Vn/Rn). Each input is weighted by Rf/Rin ratio, not just simple addition.

Current-series (shunt-series) feedback increases both input impedance (series connection) and output impedance (current feedback). This is used in circuits requiring high impedances.

Bridge amplifiers (like instrumentation amp derivative) reject common-mode signals while amplifying differential signals from sensors, ideal for noisy environments.

Coupling capacitors block DC bias from one stage to the next, preventing Q-point shifts. They allow AC signal passage while maintaining proper biasing independently in each stage.

PSRR (in dB or V/V) measures how much power supply voltage variations appear at output. Higher PSRR (more negative in dB) = better rejection. PSRR varies with frequency and is crucial for low-noise applications.