Download Electronics 2 - Philadelphia University Jordan

Form No. T651
Philadelphia University
Faculty of Engineering
Student Name:
Student Number:
Dept. of Communications and Electronics Engineering
Course Title: Electronics 2
Course No: 650321
Lecturer: Dr. Wagah F. Mohammad
Section: 1
This question is general: Tick (√) the correct answer.
 One of the following Transistor configurations has low output resistance:
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 One of the following Transistor configurations has low input resistance:
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 One of the following Transistor configurations has good frequency response:
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 One of the following Transistor configurations can be used as voltage amplifier only:
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 One of the following Transistor configurations : can be used as current amplifier only
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 One of the following Transistor configurations: can be used as power amplifier:
 Common emitter configuration.
 Common collector configuration.
 Common base configuration.
 As the source resistance increased the total voltage gain of an amplifier will be :
 Increased.
 Decreased.
 Not affected.
 The total voltage gain becomes higher if the load resistance (RL) becomes:
 Higher than output resistance (Rout).
 Equal to output resistance (Rout).
 Lower than output resistance (Rout).
 The total current gain of an amplifier will be increased if the load resistance (RL) :
 Increased.
 Decreased.
 Not affected.
 The total voltage gain of a system composed of four stages A1, A2, A3 and A4 is:
 Avt= Av1+ Av2 +Av3 +Av4
 Avt= Av1- Av2 -Av3 -Av4
 Avt= Av1 .Av2 .Av3 .Av4
 Cascode amplifier is designed to provide:
 High voltage gain.
 High input impedance.
 High output impedance.
 Darlington pair configuration compose an amplifier having a very large:
 Voltage gain.
 Current gain.
 Output resistance.
 The output resistance of Darlington pair configuration is:
 Very small.
 Medium.
 Very large.
 The output resistance (Rout) of Darlington pair configuration is equal to:
 Rout=BD rπ.
 Rout=BD / rπ.
 Rout= rπ /BD.

 An ideal current source has internal resistance equal to:
 Few Ohms
 Few tens of Ohms
 Few Mega Ohms.
 Widler current source achieve:
 Very small output resistance.
 Medium output resistance.
 Very large output resistance.
 BiCMOS technology is designed with CMOS is the input device and bipolar is output device in
order to provide:
 Low input resistance.
 High input resistance.
 Low output resistance.
 The total voltage gain of cascode BiCMOS
amplifier is equal to:
 gm1β2ro2.
 gm1gm2ro1.
 gm1gm2ro2.
I
Vbias
Vin
Vout
T2(BJT)
T1(MOS)
 The cascode amplifier consists of common emitter followed by common base. The common base
acts as:
 Voltage buffer.
 Resistance buffer.
 Current buffer.
 The cascode amplifier consists of common emitter followed by common base. It receives current
signal at low input resistance and delivers an almost equal current to the load at:
 Very low output impedance.
 Very high output impedance.
 At the same value of input resistance.
 The active BJT load transistor is usually connected as a constant current source in order to
provide:
 Very low output resistance.
 Very high output resistance.
 Very high current gain.
 Very low current gain.
VDD
 For MOS Diff. Amp. The value of
differential input voltage (Vdin) that produce
full current switching (I) is:
Vout
 Vdin=2(Vgs-Vt).
T2
T
1
Vin
 Vdin=√2(Vgs-Vt).
 Vdin= (Vgs-Vt).
I
 Suppose Vt=1Vand K=40µA/V2 for the MOS Diff. Amp.; the value of the differential input
voltage (Vdin) that produce full current switching current I=20 µA is:
 1V
 1.4V
 -1V
 Differential amplifiers is called Double ended if the input signal is applied to:
 One input with other input is connected to ground.
 Between the two inputs.
 Both inputs.
 Differential amplifiers is called single ended if the input signal is applied to:
 One input with other input is connected to ground.
 Between the two inputs.
 Both inputs.
 Differential amplifiers is called common mode if the input signal is applied to:
 One input with other input is connected to ground.
 Between the two inputs.
 Both inputs.
 Increasing the common mode rejection ratio(CMRR) in operational amplifier will result in:
 Lower voltage gain.
 Higher voltage gain.
 Does not change the voltage gain.
 Very large gain is the main feature of operational amplifier if it is connected as:
 Common mode.
 Single ended.
 Double ended.
 In differential amplifier ; the ratio of total collector resistance to the total emitter resistance
represents the:
 Current gain.
 Voltage gain.
 Output resistance.
 Input resistance.
 The OP AMP shown in the figure is connected as inverting amplifier. Virtual ground means
terminal 1 is:
Rf
 Having zero voltage
Vin R
 Physically connected to ground.
_
Vout
V1 1OP
 Neither zero voltage nor connected to ground.
V2
2+
 The OP AMP is connected as :
 Integrator.
 Differentiator.
 Unity gain amplifier.
Cf
Vin
R
-
OP
+
 Summing Amplifier.
Rf
Vout
Vin
C
_
OP
+
Vout
Vin
R
_
OP
+
Vout
 The OP AMP is connected as a differential amplifier:
 Vout = 10V.
 Vout = 5V.
 Vout = 0V.
 The OP AMP is connected as a differential amplifier:
 Rin=20K.
 Rin=10K.
 Rin=5K
5R
V1=-1V
V2=1V
R
R
5R
100K
V1 10K
Rin
V2
10K
100K
_
OP
+
 Power amplifiers are characterized by:
 Small output resistance.
 Medium output resistance.
 Large output resistance.
 Power amplifiers deliver the output signal to the load without loss of gain due to its:
 Low input resistance.
 High input resistance.
 Low output resistance.
 High output resistance.
 The power dissipated in the in the output stage transistors of power amplifiers must be:
 As low as possible.
 As high as possible.
 Maximum.
 Medium.
 Minimum.
 Class B amplifier provides an output varying with the input signal for:
 Less than 180o.
 180o.
 360o.
 Class A amplifier provides an output varying with the input signal for:
 Less than 180o.
 180o.
 360o.
 Class AB amplifier provides an output varying with the input signal for:
 Less than 360o and greater than 180o.
 180o.
 360o.
_
OP
Vout
+
Vout
 Class C amplifier provides an output varying with the input signal for:
 Less than 360o and greater than 180o.
 Less than 180o.
 360o.
 180o
 One of the following power amplifiers may be biased for the output signal to vary for
higher than 180o and lower than 360o:
 Class A amplifier.
 Class B amplifier.
 Class AB amplifier.
 Transformer is used in transformer coupled class A amplifier in order to:
 Increase the output resistance of the system.
 Increase the efficiency of the system.
 Isolate the output from the input.
 Power BJT transistors dissipate a large amount of power in their :
 Emitter –Base Junction.
 Collector –Base Junction.
 Emitter –Collector Junction.
 Which is of the following power amplifiers has the highest power conversion efficiency:
 Class A amplifier.
 Class B amplifier.
 Class C amplifier.
 Crossover distortion in class B amplifier occurs where transistors are:
 One is off and the other is on.
 Both transistors are on.
 Both transistors are off.
 Since we wish to be able to dissipate large amount of power in power transistors: The
value of thermal power coefficient (θJA) should be:
 As large as possible.
 As small as possible.
 Any value.
 0.7Av is chosen to be the gain at the cutoff frequency because:
 The output current is dropped to half.
 The output resistance is dropped to half.
 The output power is dropped to half.
 Decoupling capacitors (Cs & Cc) and by pass capacitors effect only the;
 High frequency response.
 Medium frequency response.
 Low frequency response.
 Active device , wiring and inter electrode capacitors effect only the:
 High frequency response.
 Medium frequency response.
 Low frequency response.
 The capacitive elements that effect the high frequency response are:
 Decoupling capacitors.
 By pass capacitors.
 Active device capacitances.
 The miller effect input capacitance appears at high frequency will increase the input
capacitance by:
 Av
 1-Av
 1/Av
 The miller effect output capacitance appears at high frequency will increase the output
capacitance by:
 Av
 1-Av
 1-1/Av
 At high frequency; the reactance’s of input and output capacitances of amplifiers will
decreases and consequently result in:
 Increasing the gain of the amplifier.
 Decreasing the gain of the amplifier.
 Does not affect the gain of the amplifier.
 Due to the Miller effect at high frequency; the frequency response of common base
compared with common emitter result in:
 Wider frequency response.
 Lower frequency response.
 No difference between them.
 fβ & fα are the cutoff frequencies for common emitter compared and common base
consequently thus:
 fβ >> fα .
 fβ << fα .
 fβ = fα.