Introduction to amplifiers
What are the electronic amplifiers?
Electronic amplifiers are electronic circuits for amplifying an electrical signal.
What is the amplifier in the common emitter junction?
An electronic circuit with a base in the input and a collector in the output circuit, and the emitter is common.
In a static operating point, the collector current Ict does not depend on the __________ amplification factor.
Current.
What is the amplitude-frequency characteristic?
The dependence of output signal amplitude on input frequency.
What is the basic characteristic of the common-collector configuration?
It has high input impedance and low output impedance.
What are electrical signals?
Electrical signals are time-varying voltages and currents.
Which amplifier is the amplifier with the highest current and voltage gain?
Amplifier in common emitter junction.
What is feedback?
Feedback is the action of the amplifier's output stage on the input stage. A portion of the output signal is fed back through the feedback branch and affects the input signal.
How is the amplitude-frequency characteristic measured?
Excite the system with different frequencies and measure the output amplitude.
What is another name for the common-collector, and what is its purpose?
It’s called an emitter follower, used for impedance matching.
What is the difference between DC amplifiers and AC amplifiers?
The difference is that DC amplifies both DC and AC signals, while AC amplifies only AC signals.
How is the operating point set for the transistor to work as an amplifier?
The operating point is placed in the normal active area.
What is the condition for stability?
The condition for stability is
Re≫Rb/B.
What is bandwidth?
The range of frequencies the system can transmit signals through.
Is there a phase shift between the input and output?
No, the input and output signals are in phase.
What is the gain of the amplifier and how is it expressed?
Gains are the ratios of identical output and input values. It is expressed in decibels.
What does the static work direction show?
It shows how the collector voltage and the position of the static operating point will change.
What is the input dynamic resistance of an amplifier equal to?
The input dynamic resistance of an amplifier is equal to the dynamic input resistance of the transistor.
What are the applications of the amplitude-frequency characteristic?
Filtering analysis, control, and circuit optimization.
What is the voltage gain in the common-collector configuration?
The voltage gain is approximately equal to 1.
What is static analysis?
Using static analysis, the operation of the amplifier was analyzed only for DC voltages and currents.
By how many degrees are the input and output signals shifted at the amplifier in the common emitter connection?
180°
What is the output resistance of an amplifier equal to?
The output resistance of an amplifier is equal to the parallel combination of the dynamic output resistance of the transistor.
How is the amplitude-frequency characteristic displayed?
A graph with frequency on the horizontal axis and amplitude on the vertical.
What is the purpose of the emitter resistor?
It stabilizes the transistor and reduces nonlinear distortions.