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close this bookAmplifier Teaching Aid (GTZ, DED; 86 pages)
View the documentPreface
View the documentIntroduction
Open this folder and view contentsLesson 1 - Semiconductor Review
Open this folder and view contentsLesson 2 - Bipolar Transistor
Open this folder and view contentsBipolar Transistor II
View the documentFirst Evaluation
Open this folder and view contentsLesson 4 - Transistor Fundamentals
Open this folder and view contentsLesson 5 - Transistor Biasing
Open this folder and view contentsLesson 6 - Transistor Biasing II
View the documentSecond Evaluation
Open this folder and view contentsLesson 7 - Small Signal Amplifier
Open this folder and view contentsLesson 8 - Small Signal Amplifier II
close this folderLesson 9 - Small Signal Amplifier III
close this folderLesson Plan
View the documentOther configurations
View the documentFrequency response of an amplifier
View the documentThe AC load line
View the documentHandout No. 2
View the documentWorksheet No. 9
Open this folder and view contentsLesson 10 - Large Signal Amplifier
View the documentThird Evaluation
 

Frequency response of an amplifier


Fig. 9-1: Amplifier output voltage in terms of frequency

Fig. 9-1 shows the typical frequency response of an amplifier. At low frequencies the output voltage decreases because of coupling and bypass capacitors. At high frequencies, the output voltage decreases because of transistor and stray wiring capacitance.

Critical frequencies:

Where the output voltage is 0.707 of Vmax.
Two critical frequencies -> f1, f2

Midband:

Is the band of frequencies between 10 * f1 and 0.1 * f2.
The midband is where an amplifier is supposed to be operated.

Ex: Find the midband of an amplifier with f1 = 5 Hz and f2 = 100 KHz.

10 * f1 = 10 * 5 Hz = 50 Hz -- > lower end

0.1 * f2 = 0.1 * 100 KHz = 10 KHz -- > upper end

Midband: 50 Hz - 10 KHz
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