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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.