Q.Classify amplifiers on the different criteria.

Amplifiers are grouped in several ways depending on which feature — configuration, number of stages, signal size, frequency, coupling or operating point — is used as the basis of classification.

[!ANSWER]

Amplifiers are classified by: transistor configuration (CB, CE, CC), number of stages (single-stage, multistage), signal magnitude (small-signal/voltage, large-signal/power), frequency of operation (DC, audio, video, radio-frequency), coupling used (RC, transformer, direct), and mode of operation / Q-point (Class A, B, AB, C).

[!TLDR]

Amplifiers are classified on several criteria — configuration, number of stages, signal magnitude, frequency, bandwidth, coupling, and mode of operation (Q-point) — each grouping describing a different aspect of the amplifier.

1. Based on transistor configuration: common-base (CB), common-emitter (CE) and common-collector (CC) amplifiers, according to which terminal is common to input and output.

2. Based on number of stages: single-stage amplifiers (one transistor stage) and multistage or cascaded amplifiers (two or more stages in series for higher gain).

3. Based on the magnitude of the input signal: small-signal (voltage) amplifiers, which handle weak signals and are designed for maximum voltage gain, and large-signal (power) amplifiers, which handle large signals and deliver appreciable power to the load.

4. Based on the frequency of operation: DC amplifiers (down to zero frequency), audio-frequency (AF) amplifiers (about 20 Hz-20 kHz), video amplifiers (wideband), and radio-frequency (RF) amplifiers (high frequency).

5. Based on bandwidth: narrow-band (tuned) amplifiers, which amplify a small band around a resonant frequency, and wideband amplifiers, which amplify a large range uniformly.

6. Based on the type of coupling used between stages: RC coupled, transformer coupled and direct coupled amplifiers.

7. Based on the mode of operation / position of the Q-point: Class A (conduction 360°), Class B (180°), Class AB (between 180° and 360°) and Class C (less than 180°).

[!ANSWER]

Amplifiers are classified by configuration (CB/CE/CC), number of stages (single/multistage), signal magnitude (voltage/power), frequency (DC, AF, video, RF), bandwidth (tuned/wideband), coupling (RC, transformer, direct), and operating mode/Q-point (Class A, B, AB, C).