Bipolar Junction Triodes (BJTs) topics include: The basics of BJT, device structures and physical operations, circuits, current-voltage properties, amplifier design, signal operations and circuit configuration and biasing. A Bipolar Junction Transistor (BJT) is a three-terminal semiconductor device that can amplify signals. It's a current-controlled device that consists of two p-n junctions, a common region called the base, and two outer regions called the emitter and collector.  BJTs are known as bipolar transistors because they involve the operation of charge carriers of both polarities.... Show more

Bipolar Junction Triodes (BJTs) topics include: The basics of BJT, device structures and physical operations, circuits, current-voltage properties, amplifier design, signal operations and circuit configuration and biasing.

A Bipolar Junction Transistor (BJT) is a three-terminal semiconductor device that can amplify signals. It's a current-controlled device that consists of two p-n junctions, a common region called the base, and two outer regions called the emitter and collector. 

BJTs are known as bipolar transistors because they involve the operation of charge carriers of both polarities. They can function as current regulators by allowing a small current to control a larger current. 
BJTs can consist of either a P-N-P or an N-P-N semiconductor “sandwich” structure. In a PNP transistor, the regions are, respectively, p type, n type, and p type. In an NPN transistor, the regions are n type, p type, and n type. 

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Electronic Devices and Circuits Practice Test: Bipolar Junction Triodes (BJTs)

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25 Questions

1. Find Vb2/Vb1 from the following figure.

-100 V/V-51 V/V-34 V/V– 68.1 V/V

2. An amplifier is measured to have an internal resistance of 10 kΩ, voltage gain of 100V/V and output resistance of 100 Ω. Also, when a load resistance of 1 kΩ is connected between the output resistance if found to decrease to 8 kΩ. If the amplifier is fed with the signal source having an internal resistance of 2 kΩ. Find Av.

9.09 V/V100 V/V90.9 V/V10 V/V

3. The SI units of transconductance is

Volt/ ampereOhmAmpere/ voltSiemens

4. A transistor with ß = 120 is biased to operate at a dc collector current of 1.2 mA. Find the value of gm.

24 mA/V12mA/V36 mA/V48 mA/V

5. An FH binary orthogonal FSK system employs an m 15 stage liner feedback shift register that generates an ML sequence. Each state of the shift register selects one of L non over lapping frequency bands in the hopping pattern. The bit rate is 100 bits/s. The demodulator employ non coherent detection. Suppose the hop rate is increased to 2 hops/bit and the receiver uses square law combining the signal over two hops. The hopping bandwidth for this channel is?

1.6384 MHz26.2136 MHz13.1068 MHz3.2767 MHz

6. A fast FH/MFSK system has the following parameters.
Number of bits per MFSK symbol = 4
Number of pops per MFSK symbol = 4
The processing gain of the system is

0 dB12 dB9 dB7 dB

7. For a BJt Vt is 5 V, Rc = 1000 ohm and bias current Ic is 12 mA. The value of the voltage gain is __________

-1.2 V/V-2.4 V/V-3.6 V/V-4.8 V/V

8. For the amplifier circuit in the below figure with Vcc = +10 V, Rc = 1 kΩ and the DC collector bias current equal to Ic. Find the voltage gain.

400 Ic800 Ic200 Ic100 Ic

9. Collector current (Ic) reaches zero when

Vce = Vt ln (I/Isc)Vt = Vce ln (Isc/I)Vce = Vt ln (Isc/I)Vce = Vt ln (Isc + I/I)

10. For the amplifier circuit in the below figure with Vcc = +10 V, Rc = 1 kΩ and the DC collector bias current equal to Ic. The maximum possible positive output signal swing as determined by the need to keep the transistor in the active region.

10.3 + Ic10.3 – Ic9.7 – Ic9.7 + Ic

11. For the BJT amplifier circuit with Vcc = +10 V, Rc = 1 kΩ and the DC collector bias current equal to 5 mA. The maximum possible negative output signal swing as determined by the need to keep the transistor in the active region.

0.5 V1 V10 V5 V

12. A designer wishes to create a BJT amplifier with a gm of 50 mA/V and a base input resistance of 2000 O or more. What emitter bis current should he choose?

1.16 mA1.26 mA1.36 mA1.06 mA

13. The circuit shown below is a small sine wave signal with average zero and transistor ß. Find R(C) to establish a dc collector voltage of about +5V.

5 kΩ20 kΩ15 kΩ10 kΩ

14. The number of pn junctions in a BJT is/are

2314

15. On which of the following does the scale current not depends upon?

Volume of the base-emitter junctionElectron diffusivityEffective width of the baseCharge of an electron

16. The range for the transistor parameter also referred as common-emitter current gain has a value of__________ for common devices.

50-200400-600750-1000> 1000

17. Consider the circuit graph shown in figure below. Each branch of circuit graph represent a circuit element. The value of voltage V1 is:

30 V20 V15 V25 V

18. The magnitude of the thermal voltage is given by

q/KtkT/qk/TqTk/q

19. For the amplifier circuit in the below figure with Vcc = +10 V, Rc = 1 kΩ and the DC collector bias current equal to Ic. The maximum possible negative output signal swing as determined by the need to keep the transistor in the active region.

100 Ic10 Ic0.1 IcIc

20. The potential difference between the base and the collector Vcb in a pnp transistor in saturation region is ________

-0.5V-0.2 V0.2 V0.5 V

21. Which of the following is not a part of a BJT?

BaseCollectorEmitterNone of these

22. A transistor with ß = 120 is biased to operate at a dc collector current of 1.2 mA. Find the value of Re.

25.2 ohm30.4 ohm20.6 ohm2.5 ohm

23. An amplifier is measured to have an internal resistance of 10 kΩ, voltage gain of 100V/V and output resistance of 100 Ω. Also, when a load resistance of 1 kΩ is connected between the output resistance if found to decrease to 8 kΩ. If the amplifier is fed with the signal source having an internal resistance of 2 kΩ. Find Ai.

182 A/A728 A/A364 A/A546 A/A

24. A rate 1/2 convolution code with dfrec = 10 is used to encode a data sequence occurring at a rate of 1 kbps. The modulation is binary PSK. The DS spread spectrum sequence has a chip rate of 10 MHz. The processing gain is?

37 dB14 dB104 dB58 dB

25. The energy required to move 120 coulomb through 3 V is _________

25 mJ2.78 mJ40 J360 J