OBSERVATION

It was reported that this question received the poorest responses from the candidates, which is surprising, as the questions are familiar.

• impedance matching is arranging to have one impedance as the complex conjugate of the some other; that the share the same resistance but their reactances are equal in magnitude and ‘opposite’ in type. If one is capacitive, the other is inductive. Many candidates saw this only as a means of ensuring the transfer of maximum power from source to connected load.
• Class A amplifier is by definition, one, whose quiescent (Q)-point is located in the linear region of its output characteristics, That the ‘output flows for the complete cycle of the input’ as quite a few candidates as reported referred to it as a consequence of the location of the Q-point.
• Biasing circuit is amplifier design, establishes the operating point for the active device.

 

The expected responses were:

(a)(i)Impedance matching is the principle of providing maximum power transferbetween
input and output of a system.

(ii)Class A amplifier:  The type of amplifier biased in such a way that the collector current flows throughout the full cycle (3600) of the input signal.

 (iii)Biasing circuit is an electronic means used to give power to an electronicdevice for
the purpose of establishing the proper operating conditions.

 

(b)Applications of class A amplifier

• Video Amplifier
• IF Amplifier
• RF Amplifier
• Voltage amplifier
• Power amplifier