Classes of amplifier operations: Class A B C

Q 1. Which class of amplifier has the lowest efficiency ?

   (a)Class A   (b)Class B   (c)Class C  (d)Class AB


Q2.A push pull amplifier is biased

(a) Class A    (b)Class C   (c) Class AB     (d)Class B


Q3 Maximum efficiency of a Class A amplifier is

 (a) 50%              (b)78.5 %       (c)80%   (d)100%


Q4 Which of the follwing typs of  amplifiers corresponds to a half wave rectifier ?

 (a)Class A   (b)Class B   (c)Class C    (d)class AB


Q5 Which type of power amplifier is biased for operation at less than 180º of the cycle?

(a)Class A   (b)Class B   (c)Class C    (d)class AB



_____________________________SOLUTIONS____________________________________
Q1.Ans: a

Q2. Ans: d,In Class B operatio, the linear operation of Class A can be obtained by using two matched transistors in push pull , each of them operating for half of the input signal period.
Q3. Ans b
Memorise the Hint:
ɳ CLASS Cab BA amplifier ==>i.e 100% ,50-78.5%,78.5%,50%  
Distortion proportional to Efficiency.
Conduction angle ===> Class C 90, class B 180,Class A 360

	class C	Class AB	Class B	Class A
Efficiency ɳ	100%	50% -78.5 %	78.5%	50%
Conduction angle	small (~90 Degree)	360 to 180 Degree	180 Degree	360 Degree
Bias	Revote	Forward	zero	Forward
Distortion	Extream	Moderate	High	Low

Q4. Ans b

Q5. Ans c