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ME3000 Analog Electronics
Lab 6 - 2/19
1.
Introduction
A Class A transistor amplifier is biased so that the transistor conducts continuously. The transistor of
the Class A amplifier is biased in the active region during the whole duration of operation. The Class A
amplifier is a linear amplifier since the transistor operation in the active region is almost linear. Two
types of amplifiers can be designed – tuned and untuned amplifiers. An untuned amplifier has a wider
bandwidth than a tuned amplifier, as shown in Figure 1.
A tuned amplifier consists of a resonance network as illustrated in Figure 2. It includes a parallel RLC
tank circuit. This circuit will experience high impedance and maximum voltage gain at the resonance
frequency. The resonance frequency can be calculated by
LC
f
o
2
1
.
R
C
L
Untuned amplifier
frequency response
Tuned amplifier
frequency response
Voltage
gain
Figure 1 – Class A Amplifier Frequency Response
Figure 2 – RLC Tank Circuit Schematic Diagram
Frequency
