Question
In a CE transistor amplifier there is a current and voltage gain associated with the circuit. In other words there is a power gain. Considering power a measure of energy, does the circuit voilate conservation of energy?
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Answer
Key concept: Different gain in CE transistor amplifier:
- Ac current gain: $\beta_\text{ac}=\Big(\frac{\Delta\text{i}_\text{c}}{\Delta\text{i}_\text{b}}\Big)\text{V}_\text{CE}=\text{constant}$
- dc current gain: $\beta_\text{dc}=\frac{\text{i}_\text{c}}{\text{i}_\text{b}}$
- Voltage gain: $\text{A}_\text{v}=\frac{\Delta\text{V}_0}{\Delta\text{V}_\text{i}}=\beta_\text{ac}\times\text{Resistance gain}$
- Power gain: $=\frac{\Delta\text{P}_0}{\Delta\text{P}_\text{i}}=\beta_\text{ac}^2\times\text{Resistance gain}$
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