ELECTRONICS AND COMMUNICATION PAGE 5
Contributed by Mercy Benyl
201) What is meant by a bus?
A bus is a group of conducting lines that carriers data, address, & control signals.
202) What is Tri-state logic?
Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tristate logic has a third line called enable line.
203) Give an example of one address microprocessor?
8085 is a one address microprocessor.
204) In what way interrupts are classified in 8085?
In 8085 the interrupts are classified as Hardware and Software interrupts.
205) Examples of Software interrupts?
RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7.
206) Examples of Hardware interrupts?
TRAP, RST7.5, RST6.5, RST5.5, INTR.
207) Which interrupt has the highest priority?
TRAP has the highest priority.
208) Give the expression for Hall coefficient.
RH = 1/ ρ = VH w/ BI
Where RH - Hall coefficient VH – Hall voltage
w – width of the semiconductor
B - transverse magnetic field
I – Current across the specimen
209) Give the expression for mobility in terms of Hall coefficient.
µ = σ RH
Where RH - Hall coefficient µ – mobility σ – conductivity
210) What is VOIP ?
VoIP (voice over IP) is an IP telephony term for a set of facilities used to manage the delivery of voice information over the Internet. VoIP involves sending voice information in digital form in discrete packets rather than by using the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.
211) why the input resistance of an op-amp is high whereas it's output resistance is low?
Loading at the input point and to pass the maximum output to the load is the requirement of Op-Amp which is a current exchange device from input side to output side.
212) what do you understand by microwaves? why these are called micro?
Micro waves are those waves whose wavelength is less than a foot(30 cms) or freq ranging from 1 GHz to 1000 GHz. Because of there tinyness these are called micro.
213) Name 5 different addressing modes?
Immediate, Direct, Register, Register indirect, Implied addressing modes.
214) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable". Applications of FPGAs include digital signal processing, software-defined radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio astronomy, metal detection and a growing range of other areas.
215) What is Extrinsic Semiconductor?
If certain amount of impurity atom is added to intrinsic semiconductor the resulting semiconductor is Extrinsic or impure Semiconductor.
216) What are the types of Extrinsic Semiconductor?
P-type Semiconductor and N- Type Semiconductor.
217) What is P-type Semiconductor?
The Semiconductor which are obtained by introducing pentavalent impurity atom (phosphorous, antimony) are known as P-type Semiconductor.
218) What is N-type Semiconductor?
The Semiconductor which is obtained by introducing trivalent impurity atom (gallium, indium) are known as N-type Semiconductor.
219) What is doping? P
rocess of adding impurity to a intrinsic semiconductor atom is doping. The impurity is called dopant.
220) What is CDMA, TDMA, FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.
221) What is meant by biasing a PN junction?
Connecting a PN junction to an external voltage source is biasing a PN junction.
222) What are the types of biasing a PN junction?
1. Forward bias 2. Reverse bias.
223) What is forward bias and reverse bias in a PN junction?
When positive terminal of the external supply is connected to P region and negative terminal to N region ,the PN junction is said to be forward biased. under forward biased condition the PN region offers a very low resistance and a large amount of current flows through it.
224) What is reverse bias in a PN junction?
When positive terminal of the external supply is connected to N type and negative terminal to P type then the PN junction is said to be in reverse bias. Under reverse biased condition the PN region offers a very high resistance and a small amount of current flows through it.
225) What is Reverse saturation current?
The current due to the minority carriers in reverse bias is said to be reverse saturation current. This current is independent of the value of the reverse bias voltage.
226) Explain RF?
Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.
227) What is modulation? And where it is utilized?
Modulation is the process of varying some characteristic of a periodic wave with an external signals. Radio communication superimposes this information bearing signal onto a carrier signal. These high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances. The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal. Modulation is utilized to send an information bearing signal over long distances.
228) Name the modulation techniques.
For Analog modulation--AM, SSB, FM, PM and SM Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM
229) Define Potential.
A potential of V volts at point B with respect to point A, is defined as the work done in taking unit positive charge from A to B , against the electric field.
230) Give the expression for Equation of motion.
Y = e x є x t2/ 2m
231) What is Transit time? Give the expression for it.
It is the time taken by the electron to travel a distance ‘d’ between the plates.
τ = (2 x m / e x v) ½ x d
232) What is the Force experienced by an electron in Magnetic field?
Fm = B x e x V Newton’s
233) Define Current density.
It is defined as the current per unit area of the conducting medium. J = I / A
234) Define Electron volts.
If an electron falls through a potential of one volt then its energy is 1 electron volt.
1 eV = 1.6 x 10 -19 joules
235) What is an Integrated Circuit?
An integrated circuit (IC), also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance, and very small size.
236) What is the diffusion length for holes (Lp)?
Diffusion length of holes can be said as the mean distance of travel of hole before recombination. Lp = ( Dp τp)1/2
237) State the law of junction relating the boundary value of injected minority carrier concentration with applied voltage?
The law of junction gives the density of minority carriers injected into a material across the junction. In a pn junction diode, concentration of holes injected in to the n region is given by
Pn(0) = pno ev/vT
238) Give the diode current equation?
I = I0. ( e V / ή.VT -1)
Where I –total diode current, I0. - reverse saturation current, V – Applied voltage, ή – Constant which is 1 for Germanium and 2 for Silicon, VT - voltage equivalent of temperature (VT = T/11600)
239) What is crosstalk?
Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.
240) What are conductors? Give examples?
Conductors are materials in which the valence and conduction band overlap each other so there is a swift movement of electrons which leads to conduction. Ex. Copper, silver.
241) What are insulators? Give examples?
Insulators are materials in which the valence and conduction band are far away from each other. So no movement of free electrons and thus no conduction. Ex glass, plastic.
242) What is a rectifier?
A rectifier changes alternating current into direct current. This process is called rectification. The three main types of rectifier are the half-wave, full-wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current. HWR- The simplest type is the half-wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forward-biased and current flows through it. When the voltage is negative, the diode is reverse-biased and the current stops. The result is a clipped copy of the alternating current waveform with only positive voltage, and an average voltage that is one third of the peak input voltage. This pulsating direct current is adequate for some components, but others require a more steady current. This requires a full-wave rectifier that can convert both parts of the cycle to positive voltage. FWR- The full-wave rectifier is essentially two half-wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the circuit to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.
243) What are different types of antennas ?
An antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In other words, antennas convert electromagnetic radiation into electric current, or vice versa. They are used to transmit and receive electromagnetic radiation of radio frequency, that is, radio waves, and are a necessary part of all radio equipment There are different types of antennas, they can mainly divided into directional & undirectional a simply type of directional antennas: helical antenna a simple type of undirectional antennas: yagi & loop antennas
244) What is Yagi-Uda antenna ?
Directional antenna system consisting of an array of a dipole and additional closely coupled parasitic elements (usually a reflector and one or more directors). The dipole in the array is driven, and another element, typically 5% longer, effectively operates as a reflector. Other parasitic elements shorter than the dipole may be added in front of the dipole and are referred to as directors
245) Give the relation for concentration of holes in the n- type material? p
n = ni2 /ND Where
pn - concentration of holes in the n – type semiconductor
ND - concentration of donor atoms in the n – type semiconductor
246) Give the relation for concentration of electrons in the p - type material?
np = ni2 /NA Where
np - concentration of electrons in p- type semiconductor
ND - concentration of acceptor atoms in the p – type semiconductor
A bus is a group of conducting lines that carriers data, address, & control signals.
202) What is Tri-state logic?
Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tristate logic has a third line called enable line.
203) Give an example of one address microprocessor?
8085 is a one address microprocessor.
204) In what way interrupts are classified in 8085?
In 8085 the interrupts are classified as Hardware and Software interrupts.
205) Examples of Software interrupts?
RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7.
206) Examples of Hardware interrupts?
TRAP, RST7.5, RST6.5, RST5.5, INTR.
207) Which interrupt has the highest priority?
TRAP has the highest priority.
208) Give the expression for Hall coefficient.
RH = 1/ ρ = VH w/ BI
Where RH - Hall coefficient VH – Hall voltage
w – width of the semiconductor
B - transverse magnetic field
I – Current across the specimen
209) Give the expression for mobility in terms of Hall coefficient.
µ = σ RH
Where RH - Hall coefficient µ – mobility σ – conductivity
210) What is VOIP ?
VoIP (voice over IP) is an IP telephony term for a set of facilities used to manage the delivery of voice information over the Internet. VoIP involves sending voice information in digital form in discrete packets rather than by using the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.
211) why the input resistance of an op-amp is high whereas it's output resistance is low?
Loading at the input point and to pass the maximum output to the load is the requirement of Op-Amp which is a current exchange device from input side to output side.
212) what do you understand by microwaves? why these are called micro?
Micro waves are those waves whose wavelength is less than a foot(30 cms) or freq ranging from 1 GHz to 1000 GHz. Because of there tinyness these are called micro.
213) Name 5 different addressing modes?
Immediate, Direct, Register, Register indirect, Implied addressing modes.
214) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured by the customer or designer after manufacturing—hence "field-programmable". Applications of FPGAs include digital signal processing, software-defined radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio astronomy, metal detection and a growing range of other areas.
215) What is Extrinsic Semiconductor?
If certain amount of impurity atom is added to intrinsic semiconductor the resulting semiconductor is Extrinsic or impure Semiconductor.
216) What are the types of Extrinsic Semiconductor?
P-type Semiconductor and N- Type Semiconductor.
217) What is P-type Semiconductor?
The Semiconductor which are obtained by introducing pentavalent impurity atom (phosphorous, antimony) are known as P-type Semiconductor.
218) What is N-type Semiconductor?
The Semiconductor which is obtained by introducing trivalent impurity atom (gallium, indium) are known as N-type Semiconductor.
219) What is doping? P
rocess of adding impurity to a intrinsic semiconductor atom is doping. The impurity is called dopant.
220) What is CDMA, TDMA, FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.
221) What is meant by biasing a PN junction?
Connecting a PN junction to an external voltage source is biasing a PN junction.
222) What are the types of biasing a PN junction?
1. Forward bias 2. Reverse bias.
223) What is forward bias and reverse bias in a PN junction?
When positive terminal of the external supply is connected to P region and negative terminal to N region ,the PN junction is said to be forward biased. under forward biased condition the PN region offers a very low resistance and a large amount of current flows through it.
224) What is reverse bias in a PN junction?
When positive terminal of the external supply is connected to N type and negative terminal to P type then the PN junction is said to be in reverse bias. Under reverse biased condition the PN region offers a very high resistance and a small amount of current flows through it.
225) What is Reverse saturation current?
The current due to the minority carriers in reverse bias is said to be reverse saturation current. This current is independent of the value of the reverse bias voltage.
226) Explain RF?
Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.
227) What is modulation? And where it is utilized?
Modulation is the process of varying some characteristic of a periodic wave with an external signals. Radio communication superimposes this information bearing signal onto a carrier signal. These high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances. The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal. Modulation is utilized to send an information bearing signal over long distances.
228) Name the modulation techniques.
For Analog modulation--AM, SSB, FM, PM and SM Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM
229) Define Potential.
A potential of V volts at point B with respect to point A, is defined as the work done in taking unit positive charge from A to B , against the electric field.
230) Give the expression for Equation of motion.
Y = e x є x t2/ 2m
231) What is Transit time? Give the expression for it.
It is the time taken by the electron to travel a distance ‘d’ between the plates.
τ = (2 x m / e x v) ½ x d
232) What is the Force experienced by an electron in Magnetic field?
Fm = B x e x V Newton’s
233) Define Current density.
It is defined as the current per unit area of the conducting medium. J = I / A
234) Define Electron volts.
If an electron falls through a potential of one volt then its energy is 1 electron volt.
1 eV = 1.6 x 10 -19 joules
235) What is an Integrated Circuit?
An integrated circuit (IC), also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance, and very small size.
236) What is the diffusion length for holes (Lp)?
Diffusion length of holes can be said as the mean distance of travel of hole before recombination. Lp = ( Dp τp)1/2
237) State the law of junction relating the boundary value of injected minority carrier concentration with applied voltage?
The law of junction gives the density of minority carriers injected into a material across the junction. In a pn junction diode, concentration of holes injected in to the n region is given by
Pn(0) = pno ev/vT
238) Give the diode current equation?
I = I0. ( e V / ή.VT -1)
Where I –total diode current, I0. - reverse saturation current, V – Applied voltage, ή – Constant which is 1 for Germanium and 2 for Silicon, VT - voltage equivalent of temperature (VT = T/11600)
239) What is crosstalk?
Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.
240) What are conductors? Give examples?
Conductors are materials in which the valence and conduction band overlap each other so there is a swift movement of electrons which leads to conduction. Ex. Copper, silver.
241) What are insulators? Give examples?
Insulators are materials in which the valence and conduction band are far away from each other. So no movement of free electrons and thus no conduction. Ex glass, plastic.
242) What is a rectifier?
A rectifier changes alternating current into direct current. This process is called rectification. The three main types of rectifier are the half-wave, full-wave, and bridge. A rectifier is the opposite of an inverter, which changes direct current into alternating current. HWR- The simplest type is the half-wave rectifier, which can be made with just one diode. When the voltage of the alternating current is positive, the diode becomes forward-biased and current flows through it. When the voltage is negative, the diode is reverse-biased and the current stops. The result is a clipped copy of the alternating current waveform with only positive voltage, and an average voltage that is one third of the peak input voltage. This pulsating direct current is adequate for some components, but others require a more steady current. This requires a full-wave rectifier that can convert both parts of the cycle to positive voltage. FWR- The full-wave rectifier is essentially two half-wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The positive voltage half of the cycle flows through one diode, and the negative half flows through the other. The centre tap allows the circuit to be completed because current cannot flow through the other diode. The result is still a pulsating direct current but with just over half the input peak voltage, and double the frequency.
243) What are different types of antennas ?
An antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In other words, antennas convert electromagnetic radiation into electric current, or vice versa. They are used to transmit and receive electromagnetic radiation of radio frequency, that is, radio waves, and are a necessary part of all radio equipment There are different types of antennas, they can mainly divided into directional & undirectional a simply type of directional antennas: helical antenna a simple type of undirectional antennas: yagi & loop antennas
244) What is Yagi-Uda antenna ?
Directional antenna system consisting of an array of a dipole and additional closely coupled parasitic elements (usually a reflector and one or more directors). The dipole in the array is driven, and another element, typically 5% longer, effectively operates as a reflector. Other parasitic elements shorter than the dipole may be added in front of the dipole and are referred to as directors
245) Give the relation for concentration of holes in the n- type material? p
n = ni2 /ND Where
pn - concentration of holes in the n – type semiconductor
ND - concentration of donor atoms in the n – type semiconductor
246) Give the relation for concentration of electrons in the p - type material?
np = ni2 /NA Where
np - concentration of electrons in p- type semiconductor
ND - concentration of acceptor atoms in the p – type semiconductor