Exam Questions Papers - Engineering

Q1:

A Hartley oscillator uses FET with gm of 2 ms and rd = 2 KΩ. The total coil inductance is 10 μH with turns ratio of input to output side of 1 : 10. It is tuned with a 50 pf capacitor. Find frequency of oscillations, amplifier gain margin in dB.

A 7.11 MHz, 13.97 dB

B 7.3 MHz, 14.1 dB

C 6.93 MHz, 12.9 dB

D 7.4 MHz, 13 dB

ANS:A - 7.11 MHz, 13.97 dB

= 7.11 MHz μ = gm x rd