3.BJT AMPLIFIERS –FREQUENCY RESPONSE
1.Half power gain is the maximum gain minus [ ]
a)6dB b)12dB c)3dB d)2dB
2.The capacitive reactance is equal to [ ]
a)1/(2πfc) b) (2πfc) c)πfc d) 1/(πfc)
3.The transient response is a plot of [ ]
a)voltage vstime b) voltage vscurrent c) voltage vsfrequency d)none
4.The time constant of an RC network is [ ]
a)R/C b)C/R c)1/RC d)RC
5.For the gaussian response the rise time tr &bandwidth(BW) are related by [ ]
a) tr =0.35/BW b) tr =0.5/BW c)BW=0.35 tr d) tr =0.35Bw
6.The β cutoff frequency is found from [ ]
a)CC configuration b)CE configuration c)CB configuration d)none
7. The α cutoff frequency is found from [ ]
a)CC configuration b)CE configuration c)CB configuration d)none
8.The value of α cutoff frequency is [ ]
a)greater than β cutoff frequency b)smaller than β cutoff frequency
c)equal to the β cutoff frequency d)none
9.The risetime of an amplifier is [ ]
a)proportional to square root of the upper 3-dB frequency
b)inversely proportional to the upper 3-dB frequency
c)directly proportional to the upper 3-dB frequency
d)independent of the upper 3-dB frequency
10. The emitter diffusion capacitance for a transistor is [ ]
a)proportional to square root of collector current
b)inversely proportional to collector current
c)directly proportional to collector current
d)independent of the collector current
11.In the h.f hybrid –πmodel of a CE transistor ,typical values of conductance gm is [ ]
a)10ms b)100ms c)1000ms d)104ms
12. In the h.f hybrid –πmodel of a CE transistor ,typical values of cc is [ ]
a)3PF b)100PF c)1000PF d)0.01µF
13. In the h.f hybrid –modal of a CE transistor ,typical values of ce is [ ]
a)3PF b)100PF c)0.001µF d)0.1µF
14. In the h.f hybrid –πmodel of a CE transistor ,typical values of rble is [ ]
a)100kΩ b)1000kΩ c)10kΩ d)4MΩ
15. In the h.f hybrid –πmodel of a CE transistor ,typical values of rblc is [ ]
a)100kΩ b)1000Ω c)10kΩ d)4MΩ
16.As the temperature increases, resistance parameter rb’e in the h.f hybrid- π model of a CE transistor
a)decreases b)increases [ ] c)remains unchanged d)increase ,reaches a maximum&reduces
17.As |Ic| increases the value of transconductance gm of CE transistor [ ]
a)increases as |Ic| b)increases as |Ic2| c)decreases d)remain unchanged
18.As the collector current Ic increases ,value of frequency ft [ ]
a)remains unchanged b)increases continuosly c)decreases continuosly d)increases reaches a maximum and then falls
19.parameter ft gives the frequency at which the magnitude of CE short circuit current gain is [ ]
a)half of low frequency gain b)0.707 of low frequency gain
c)one-tenth of low frequency gain d)unity
20.The product ce* ft equals [ ]
a) gm b)gm/1.414 c) gm/2π d)2π/ gm
21.The upper 3-dB frequency for CE amplifier equals [ ]
a) gble/2πc b)gble/c c) hfe / gble d) gm /hfe
22.parameter ft is approximately equal to [ ] a)gm/ ce b)gm/2π ce c) 2π ce/ gm d) hfe/fβ
23.In the high frequency hybrid –π model of CE transistor ,capacitance cc accounts for [ ]
a)excess minority carrier storage in the base region
b)collector junction barrier capacitance
c)emitter junction barrier capacitance
d) collector junction diffusion capacitance
24.In the high frequency hybrid –π model of CE transistor ,capacitance ce accounts for [ ]
a) emitter junction barrier capacitance
b) collector junction barrier capacitance
c) emitter junction diffusion capacitance
d) collector junction diffusion capacitance
25. In the high frequency hybrid –π model of CE transistor ,conductance gblc accounts for [ ]
a)bulk conductance of the base region
b)leakage conductance in the base region
c)feedback action due to base width modulation
d)none
4.MOSFET AMPLIFIERS
1. The input impedance of a CS amplifier circuit is very high at [ ]
a)high frequency b)low frequency c)mid frequency d) zero frequency
2. The voltage gain in a CD amplifier depends on [ ]
a)gm&Rd b)gm &Rs c)gm d)RD
3. A source follower can operate as a [ ]
a)voltage buffe r b)voltage amplifier c)current amplifier d)power amplifier
4. The input impedance of a MOSFET CD amplifier is very [ ]
a)low b) high c)moderate d)zero
5. In the CS configuration the input signal is applied to the [ ]
a)gate terminal b)source terminal c)drain terminal d)emitter terminal
6. An important property of cascOde amplifier is its [ ]
a)high output impedance b)low output voltage c)low voltage gain d)high input impedance
7. The source follower is [ ]
a)CD amplifier b)CS amplifier c)CG amplifier d)none of these
8. which of the following is noisy [ ]
a)FET b)BJT c)SCR d)none of these
9. Band width of ideal tuned amplifier is [ ]
a)zero b)infinite c)unity d)depend on circuit
10. FET is a [ ]
a)current controlled device b)voltage controlled device c)both a&b d)none of these
11. If the gain of the CS amplifier varies significantly with the signal swing ,then the circuit operates in [ ]
a)linear mode b)small signal mode c)large signal mode d)non-linear mode
12.If the gate &drain are shorted in a diode connected device the MOSFETcan operate as a [ ]
a)small-signal resistor b)current source c) small-signal capacitor d)voltage source
13.In a CS amplifier with a diode connected load the input-output characteristics are relatively [ ]
a)zero b)constant c)non-linear d)linear
14.The load impedance of a CS stage can be increased by a [ ]
a)high resistive load b)diode connected load c)current source load d)high capacitor value
15.In CS amplifier to achieve high voltage gain with limited supply voltage the load impedance must be
a)small b) moderate c)high d)zero [ ]
16.To achieve high voltage gain,the load of a folded cascade amplifier can be replaced by [ ]
a)CG stage b)CS stage c)CD stage d)cascade stage
17. Voltage gain of a given CS FET depends on its [ ]
a)Dynamic drain resistance b)i/p impedance
c) Amplification factor d)Drain load resistance
18) CB amplifier of BJT is similar in behaviour with following FET configuration [ ]
a)common gate amplifier b) common drain amplifier
C) common source amplifier d)swamped source resistor amplifier
19) FET amplifier configuration , which is similar to CC BJT is [ ]
a) common gate amplifier b) common drain amplifier
c) common source amplifier d) swamped source resistor amplifier
20) resultant phase shift of odd no of CE amplifier stages at mid band frequency is [ ]
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