Q.Give the comparison between CB, CC and CE amplifiers on performance characteristics.

The three configurations differ in their input and output impedances, current, voltage and power gains, phase relationship and typical uses.

[!ANSWER]

CB: low input impedance, high output impedance, current gain $\alpha<1$, high voltage gain, 0° phase, used at high frequency. CE: medium input and output impedance, current gain $\beta$, high voltage gain, highest power gain, 180° phase, general amplification. CC: high input impedance, low output impedance, current gain $1+\beta$, voltage gain just below 1, 0° phase, used for impedance matching.

[!TLDR]

CB, CE and CC amplifiers compare across input/output impedance, current, voltage and power gain, phase shift and application: CB suits high frequency, CE gives the highest power gain for general use, and CC is a low-gain impedance-matching buffer.

Comparison on performance characteristics:

1. Input impedance: CB — low (about 20-150 ohm); CE — medium (about 1-2 kohm); CC — high (up to hundreds of kohm).

2. Output impedance: CB — high (about 100 kohm-1 Mohm); CE — medium (about 10-50 kohm); CC — low (about 20-50 ohm).

3. Current gain: CB — $\alpha$, less than unity (no current gain); CE — $\beta$, high (about 20-500); CC — $1+\beta$, the highest.

4. Voltage gain: CB — high; CE — high; CC — less than unity (about 1).

5. Power gain: CB — moderate; CE — highest of the three; CC — moderate (lowest).

6. Phase difference between input and output: CB — 0° (in phase); CE — 180° (out of phase); CC — 0° (in phase).

7. Application: CB — high-frequency / RF amplifiers; CE — audio and general-purpose voltage and power amplification; CC — impedance matching / buffer (emitter follower).

[!ANSWER]

CB — low input, high output impedance, $A_i=\alpha<1$, high voltage gain, 0° phase, high-frequency use; CE — medium impedances, $A_i=\beta$, high voltage gain, highest power gain, 180° phase, general use; CC — high input, low output impedance, $A_i=1+\beta$, voltage gain below 1, 0° phase, impedance matching.