11. Barkhausen criterion for oscillator stability is :
(a) Aβ = 0
(b) Aβ = 1
(c) –Aβ = 1
(d) A = 1/radic;beta;
12. A Hartley oscillator circuit uses :
(a) Capacitive feedback
(b) A tapped inductor
(c) A tapped capacitor
(d) A tapped inductor for inductive feedback
13. For good stability, the tuned circuit should have :
(a) High Q
(b) Low R
(c) Low L
(d) Low C
14. The varactor in a voltage controlled oscillator needs :
(a) Audio signal below 1000 Hz
(b) Reverse D.C control voltage
(c) Forward bias
(d) Parallel capacitance were than 5mu;F
15. In a practical oscillator Aβ is :
(a) Slightly less than 1
(b) 1
(c) -1
(d) Slightly greater than 1
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