Difference between n type and p type semiconductor

A semiconductor which is an extremely pure form is called as the intrinsic semiconductor, A semiconductor which contains some impurities is called extrinsic semiconductor. After adding some impurities in the pure semiconductor we can improve some properties of semiconductor material. The process of adding impurities is called doping. so here the main purpose of doping is to add impurities in the semiconductor and increase the number of electrons or holes in the semiconductor material. Depending upon the added impurities p-type and n-type semiconductor can be decided so first let we understand what is the difference between intrinsic and extrinsic semiconductor after that we have to understand this topic.

Difference between N-type and P-type semiconductor listed below:
  • An N-type semiconductor is an extrinsic semiconductor while P-type semiconductor of the extrinsic semiconductor
  • In N-type semiconductor, electrons are majority carriers and holes are minority carriers while in P-type semiconductor holes are majority carriers and electrons are minority carriers
  • The N-type semiconductor has a larger electrons concentration and less hole concentration while in P-type has holes concentration and fewer electrons concentration
  • N-type has pentavalent impurities are added while in p-type trivalent impurities are added
  • N-type has donor energy levels very close to the conduction band while P-type has acceptor energy levels very close to the valance band
  • In N-type majority, carriers move from lower to higher potential while in  P-type majority carrier move from higher to lower potential
  • In N-type, the electron density is much greater than the density of the holes while in P-type holes density is much greater than the electron density
  • In N-type, the donor energy level is close to the conduction band and away from the valence band while in P-type the acceptor energy level close to the valance band and away from the conduction band
  • In N-type, the Fermi level lies between the donor energy level and the conduction band while in P-type the Fermi level lies between the acceptor energy level and the valence band
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Difference between extrinsic and intrinsic semiconductors

Here this post gives the difference between extrinsic and intrinsic semiconductor to better understand this topic.
Difference :

  • Intrinsic semiconductor also called an undoped semiconductor or basically, I type semiconductor are pure semiconductor without any significant species present. The number of charge carriers is therefore determined by the properties of the material itself instead of the number of impurities, while in the extrinsic semiconductor are impure. When a small quantity of impurity is mixed in a pure or intrinsic conductor, a conductivity of semiconductor increases. Such an impure semiconductor is called extrinsic semiconductor 
  • The electrical conductivity of an intrinsic semiconductor is poor while in extrinsic semiconductor conductivity of large
  • While we are using intrinsic semiconductor the number of holes and electrons produced due to the thermal energy are equal  but in extrinsic semiconductor, the number of electrons and holes produced due to the thermal energy are must not be equal
  • The current conduction is due to electrons and hole but in  extrinsic the current conduction is due to either holes or electrons
  •  While we have to use intrinsic semiconductor the Fermi level is at the center of the forbidden energy gap and is unchanged with a change in temperature but in extrinsic, the Fermi level shift upward or downward with a change in temperature
  • In an intrinsic semiconductor, the electrical conductivity is a function of temperature to be alone but in extrinsic semiconductor, the electrical conductivity depends upon the temperature as well as on the number of impurity atoms doped the structure
  • The impurity like arsenic, antimony, phosphorus,  and aluminum indium, etc is added to the pure form of silicon and germanium to form an extrinsic semiconductor. The pure form of silicon and germanium type of crystal is used in an intrinsic semiconductor

Advantages and disadvantages of WDM

WDM has wide application in the electronics and network communication system because of this useful feature details. Other method called DWDM, it's different from WDM. The main difference between WDM and DWDM is DWDM has a greater overall capacity so DWDM spaces the wavelength more closely than WDM. Here this post gives information about the benefits and drawback of WDM to better understand this topic.
Advantages of WDM:
  • Easier to reconfigure
  • Full duplex transmission is possible
  • It provides higher bandwidth
  • Optical component are similar and more reliable
  • High security
  • This could be the best approach as it is simple to implement
Disadvantages of WDM:
  • Signals cannot be very close
  • Lightwave carrying while using WDM are limited to 2 point circuit
  • Cost of the system increases with the addition of optical components
  • Scalability is a concern as OLT has to have transmitter array with one transmitter for each ONU. Adding a new ONU could be a problem unless the transmitter were provisioned in advance. Each ONU must have a wavelength specific laser
  • Difficulty in wavelength tuning
  • Inefficiency in BW utilization
  • Difficulty in a cascaded topology
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Difference between WDM and DWDM

The main comparison between WDM and DWDM is one of degree only. DWDM has a greater overall capacity so DWDM spaces the wavelength more closely than WDM. Here this post gives the information about WDM vs DWDM to better understand this topic.

Difference between WDM and DWDM:
  • WDM stands for wavelength division multiplexing while DWDM stands for dense wavelength division multiplexing.
  • In WDM the number of the light source are used each emits the light of different wavelength but in DWDM utilized closely spaces channels.
  • In WDM channel spacing reduces to 1.6 nm or less while in DWDM channel spacing is small 200 GHz and small.
  • In WDM optical multiplexer is used as the input side to multiplex these signal while in DWDM assign the incoming optical signal to specific frequency multiplex them for transport over a single fiber.
  • In the WDM method, all signal arrives at the same time instead of being distributed across time slots while in DWDM multiple channels of information carried over the same fiber each using individual wavelength.
  • In DWDM cost per channel is high compared to WDM.
  • In WDM number of channel delivered only two while in DWDM number of channel delivered around a hundred.
  • 1310 nm laser used in conjunction with 1550 nm lasers while in DWDM is qualified only for system Z only.
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Multicast routing protocol

A multicast routing protocol is one type of service provider and that functions as a client within the framework of the router architecture. This routing protocol manages group membership and controls the path that multicast data take over the network. The routing architecture is designed to be extended by such router client type of modules.

Multicast routing is in charge of deciding and propagating information needed to forward multicast packets outside in local area network among multiple interconnected multicast routers over the network. Multicast routing protocol which is used for graphs while in multicast routing protocol is used for a tree. 

Multicast routing protocol includes protocol independent multicast(PIM), Multicast open shortest path first(MOSPF), and Distance vector multicast routing protocol(DVMRP). The internet group management protocol(IGMP) is a special multicast protocol that acts as an intermediary between host and routers.

 Protocol dependent multicast is commonly used now. It has two flavors:
  • MOSPF: Multicast open shortest path first
  • CBT: Core-based tree
  • PIM: protocol independent multicast
Protocol independent multicast is commonly used now. It has two flavors:
  • PIM type dense mode -  This mode uses source-based trees. It is used in dense environments such as LAN.
  • PIM type sparse mode - This mode uses shared trees. It is used in a sparse environment such as WAN.

Unicast routing protocol

Before we learn about unicast routing protocol first let us understand what is unicast. There are types of routing protocol name as intradomain and interdomain. Distance vector and link state is an intradomain routing protocol while path vector is inter-domain routing protocol here this article are described to this three protocol in details.

                   

1. Distance vector routing protocols:

Distance vector is one of the simplest routing protocol which routing decision on the number of hops between source and destination. A route with less number of hops which is considered as the best route. Every router advertises its set best routers. The least cost route between any two nodes is the route with a total minimum distance. Each node maintains a vector of minimum distance to every node. Ultimately all routers build up their network topology based on the advertisement of their peer routers, for example, routing information protocol. 

2. Link state routing:

Link state routing protocol is the second family routing protocol. It is a slightly complicated protocol than distance vector. Link state routing uses link state routers to exchange message that allows each router to learn the entire network topology. All router then calculate their best path for routing purposes. Based on this learned topology, each router is then able to compute its routing table by using the shortest path computation. 

The concept of link state routing
The concept of link state routing 

Basic features of the unicast link state routing protocol: 
  • Link-state packet  considered as a: A small packet that contains routing information
  • Link state database considered as A collection information gathered from link state packet
  • Shortest path first algorithm: A calculations performed on the database results into the shortest path
  • Routing table: A first of known paths and interfaces
The figure shows that a simple five nodes. Each node uses the same topology to create a routing table bit the routing table for each and every node is unique because the calculations are based on different interpretations of the topology. While each and every person may have the same map each needs to take a different route to reach her specific destination.

Link state knowledge
Link state knowledge
 Build a routing table:
  • Creation of the states of a link by each node called as the link state packet
  • Dissemination of LSP to every other router called flooding in an efficient and reliable way
  • Formation of the shortest path tree for each node
  • Calculations of a routing table on the shortest path tree
Link state routing protocol is to compare with distance vector protocol have the following way:
  • It requires a large amount of memory
  • Shortest path computations require many CPU circles
  • It network uses the little bandwidth
  • It quickly reacts to topology changes
  • No splits horizon techniques are possible in the link state routing
  • Authentication mechanisms can be used to avoid undesired adjacency and problems
  • All neighbors must be trusted in the topology
  • All item in the database must be sent to neighbors to form link state packets 
3. Path vector method:

Distance vector and link state routing both are intradomain routing protocols. These two protocols are not suitable for interdomain routing protocol mostly because of their scalability. Both of this routing protocol became intractable when the domain of operation becomes large. Distance vector routing is subject to instability if there are more than a few hops in the domain of operation. While in path vector routing we assume that there is one node in each autonomous system that acts on behalf of the entire autonomous system.

Anycast routing

What is anycast?

Anycast is packet based forwarding mechanism where multiple hosts can have the same logical address. DNS is a traffic routing algorithm used for the speedy delivery of website content the advertises individual IP addresses on multiple nodes. 

Whenever any anycast packet is received it is enquired with DNS to where to send it. DNS provides basically IP address which is the nearest IP configured on it.

How does anycast work?

Anycast network routing is able to route for incoming connection request across multiple data centers. When a request comes into a single IP address associated with the anycast network, the network request distributes the data based on some prioritization methodology. The selection process behind choosing a particular data center will typically be optimized to reduce latency by selecting the data center with the shortest distance from the request.

Anycast routing
Anycast routing

There several advantages of anycast routing including:
  • Faster connection
  • Simplified server configuration
  • High availability
  • DDoS mitigation

Multicast routing

What is multicast routing?

Multicast routing is a method for transferring data from one source to a group of receivers simultaneously. The main goal of the router is to route the packets. While in broadcast routing packet is sent to all nodes even if they do not want it but in multicast routing the data sent to only nodes which want to receive the packets.

Multicast routing
Multicast routing

The router must know that there are nodes which wish to receive multicast packets then only it should forward. Multicast routing works spanning tree protocol to avoid looping. Multicast routing also uses reverse path forwarding techniques to detect and discard duplicates and loop. It can also help us to minimize the computational resources needed to make copies of the data and the total volume of bandwidth that otherwise would have been used to carry multiple copies of the same content.

Multicast tree:

To show in the figure, multicast routing will work on spanning type tree protocol to avoid looping. The router and the interfaces traversed by multicast date to reach its receiver form a tree. The source that transmits the data known as the root and the receivers are the leaves on the multicast tree.

Multicast routing
Multicast routing tree

Multicast routing protocols:

First, let us understand what is the multicast routing protocol. There are two types of multicast routing protocols:
  • Dense mode
  • Sparse mode
You can also learn some different routing method :

2. Anycast Routing
3. Broadcast Routing

Broadcasting routing

We all know that the broadcasting is destined to all network devices. It is a method for broadcasting to transfer a message to all recipients simultaneously. It can be performed as a high-level operation in a program. In this method, the packet is sent to all nodes even if they do not want it. Router create configured to forward broadcast in some special cases. This broadcast message is destined for all network devices.

So the router creates a data packet and then send it to each host one by one. The router creates multiple copies of a single data packets with different destination addresses. All packet are sent as unicast but because they sent all, It simulates is broadcasting.
  • This method consumes a lot of bandwidth and router must destination address of each node
  • Secondly, when a router receives a packet that is to be broadcast, it simply floods those packet out of interfaces. All routers are configured in the same way.
  • This method is easy on the router on CPU but may cause the problem of duplicate packets received from peer routers.
  • Reverse path forwarding is a technique in which router knows in advance about it predecessor from where it would receive the broadcast. This technique is used to detect and also some discard duplicates.
Broadcasting routing
Broadcasting routing

You can also learn some different routing method :

1. Unicast Routing
2. Anycast Routing
3. Multicast routing

Unicast routing

We all know that unicast means that the transmission from a single sender to a single receiver. Most of the traffic on the internet and also an intranet is known as unicast data means that unicast traffic is sent with a specified destination. Unicast is a transmission from point to point means (single sender to a single receiver). It is the simplest form of routing because the destination which is already known. There is various unicast protocol such as TCP, HTTP, etc. 

TCP is one of the uses unicast protocol. It is a connection-oriented protocol that relays on acknowledgment from the receiver side. While HTTP is an object-oriented protocol for communication.

There are basically three types of major routing protocol for unicast routing is:
  • Distance vector routing 
  • Link state routing
  • Path Vector Routing
Unicast routing
Unicast routing
You can also learn some routing techniques listed below:

 1. Broadcast Routing
2. Multicast routing
3. Anycast routing

Unicast routing protocol:

Before we learn about unicast routing protocol first let us understand what is unicast. There are types of routing protocol name as intradomain and interdomain. Distance vector and link state is an intradomain routing protocol while path vector is inter-domain routing protocol here this article are described to this three protocol in details.

                   

1. Distance vector routing protocols:

Distance vector is one of the simplest routing protocol which routing decision on the number of hops between source and destination. A route with less number of hops which is considered as the best route. Every router advertises its set best routers. The least cost route between any two nodes is the route with a total minimum distance. Each node maintains a vector of minimum distance to every node. Ultimately all routers build up their network topology based on the advertisement of their peer routers, for example, routing information protocol. 

2. Link state routing:

Link state routing protocol is the second family routing protocol. It is a slightly complicated protocol than distance vector. Link state routing uses link state routers to exchange message that allows each router to learn the entire network topology. All router then calculate their best path for routing purposes. Based on this learned topology, each router is then able to compute its routing table by using the shortest path computation. 

The concept of link state routing
The concept of link state routing 

Basic features of the unicast link state routing protocol: 
  • Link-state packet  considered as a: A small packet that contains routing information
  • Link state database considered as A collection information gathered from link state packet
  • Shortest path first algorithm: A calculations performed on the database results into the shortest path
  • Routing table: A first of known paths and interfaces
The figure shows that a simple five nodes. Each node uses the same topology to create a routing table bit the routing table for each and every node is unique because the calculations are based on different interpretations of the topology. While each and every person may have the same map each needs to take a different route to reach her specific destination.

Link state knowledge
Link state knowledge
 Build a routing table:
  • Creation of the states of a link by each node called as the link state packet
  • Dissemination of LSP to every other router called flooding in an efficient and reliable way
  • Formation of the shortest path tree for each node
  • Calculations of a routing table on the shortest path tree
Link state routing protocol is to compare with distance vector protocol have the following way:
  • It requires a large amount of memory
  • Shortest path computations require many CPU circles
  • It network uses the little bandwidth
  • It quickly reacts to topology changes
  • No splits horizon techniques are possible in the link state routing
  • Authentication mechanisms can be used to avoid undesired adjacency and problems
  • All neighbors must be trusted in the topology
  • All item in the database must be sent to neighbors to form link state packets 
3. Path vector method:

Distance vector and link state routing both are intradomain routing protocols. These two protocols are not suitable for interdomain routing protocol mostly because of their scalability. Both of this routing protocol became intractable when the domain of operation becomes large. Distance vector routing is subject to instability if there are more than a few hops in the domain of operation. While in path vector routing we assume that there is one node in each autonomous system that acts on behalf of the entire autonomous system.

ULSI full form

What is the full form of ULSI?

  • Ultra Large Scale Integration 

What does ULSI mean?

The USLI means that IC which to placing more than about one million circuit elements on a single chip. The Intel 486 and also a Pentium type of microprocessor, for example, use ULSI technology. The line between VLSI and ULSI is vague.

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Full form of INSAT

What is the full form of INSAT?

  • Indian National Satellite System

 What does INSAT  mean?

INSAT is a series of multipurpose GEO-Stationary for satellites launched by Indian space research organization for broadcasting, search, meteorology, telecommunication and rescue operations. INSAT is one of the largest domestic communication systems in the Asia Pacific region. The overall coordination and management of the INSAT system rest with the secretary level INSAT coordination committee.

Advantages and disadvantages of modem

A modem is a basic type of network device that both modulates and also has demodulated for analog carrier signals called as a sine wave for encoding and decoding digital information for processing. A modem is a combination of modulating and demodulating. This post gives information about the advantages and disadvantages of a modem to better understand this topic.

Advantages of the modem:
  • More useful in connecting LAN with the internet
  • Speed depends on the cost
  • Slow speed when compared to the hub
  • A limited number of a system can be connected 
  • A modem is most probably widely used in data communication  roadway
  • A modem converts that the digital signal into an analog signal
Disadvantages of the modem:
  • Acts just as an interface between LAN and internet
  • No traffic maintenance is present
  • A modem is not understood the intermediate process
  • The modem does not know about the own destination path
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Tunnel diode

Definition of tunnel diode:

The tunnel diode is one of the most significant solid state devices which have made their appearance in the last decade. Tunnel diode was invented in the year of 1958 by Leo Esaki. The germanium material is basically used to male tunnel diode. They can also be made from materials as gallium arsenide and silicon materials. The tunnel diode exhibits are also negative resistance in their operating range. therefore it can be used as an amplifier, oscillator and in any switching circuits.

The tunnel diode is heavily doped, highly conductive PN junction diode in which the electric current decreases as the voltage increases. It works on the principle of the method called a tunneling effect. The tunnel diode is used as a very fast switching device in the computer. The tunneling is the phenomenon of conduction in the semiconductor material in which the charge carrier punches the barrier instead of climbing through it. The tunnel diode is a two terminal device with n-type semiconductor called as a cathode and p-type semiconductor called an anode.  It is also used in high-frequency oscillators and amplifier.

Symbol of tunnel diode:

The symbol of the tunnel diode is shown in the figure given below. It is a two terminal device with p-type semiconductor acting as anode and n-type semiconductor act as a cathode. The n-type semiconductor material emits the electron so it named as the cathode while in p-type material attracts the electrons hence it named as the anode.

Tunnel diode symbol

VI characteristics of tunnel diode:
Forward bias condition:
Under the forward bias condition, the immediate conduction occurs in the diode because of heavily doped conduction happen in the diode. The current in the diode reached the maximum current that diode reached a maximum value of Ip and when the voltage applied is Vp across it. The current value is decreased when more amount of voltage is applied. And it current keep decreasing unit it reaches a minimum value. This minimum value of current is called the method valley current Iv. The tunnel diode and normal PN junction diode characteristics are different from each other.
Reverse bias condition: 
Under the reverse bias condition, the tunnel diode act as a back diode or backward diode. In reverse bias condition, the empty state on the n side aligned with the filled state on the p side. The electron will tunnel through a potential barrier. Because of its high doping concentration tunnel diode acts as an excellent conductor.
Tunnel diode characteristics
The graph above shows that A to point of B the value of current decreases with the increases in voltage. So from figure A to B, the graph shows the negative resistance region of the tunnel diode, This region shows the most important property of the diode. Here in this region, the tunnel diode produces the power instead of absorbing it.
Advantages and disadvantages of Tunnel diode:
Advantages of tunnel diode:
  • Low cost
  • Low noise
  • High speed
  • Fabrication is also very simple
  • Fast response
  • Moderate in operation
  • Low power
  • Longevity
  • Ease of operation
  • Environmental immunity
  • Insensitive to nuclear radiation
Disadvantages of tunnel diode:
  • The voltage range, which can be operated properly in 1 volt or below
  • Being two terminal device, it provides no isolation between output and input circuit
  • The low output voltage swing
  • Tunnel diode cannot be fabricated in a large number
Applications of tunnel diode:
  • Tunnel diode can be used as a switch, oscillator, and  also used in the amplifier
  • It is used as an ultra high-speed switch
  • It shows a fast response
  • It is used as an ultra 
  • It is used as a high-frequency component
  • This diode acts as a logic memory storage device
  • This diode can be used as FM receiver since it is a low current device it is not used more
  • It can be used in modern military equipment
  • This can be used as a microwave oscillator at a frequency of about 10 GHz
  • It is used in nuclear magnetic resource machine
  • It can be used in satellite communication equipment
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Difference between router and bridge

A router is a device or in some cases software in a computer device which determines the next network point to which a packet should be forwarded toward their destination. A router is located at any gateway include as part of a network switch while the bridge is a product that connects LAN  to another LAN that uses the same protocol. Here this article gives the difference between router and bridge to better understand this topic. 
  • The router operates in the network layer of the OSI model while the bridge operates in a data link layer of the OSI model
  • A router is used to connect the LAN and WAN while in a bridge is used to connect two different LAN segments
  • Router transmit data in the form of packets while in bridge transmit data in the form frames
  • The router reads the IP address of the devices, Bridge read the MAC address of a device
  •  The router has more ports than a bridge, Bridge has only two ports
  • A router uses the table for sending data whereas bridge does not use any a routing table for sending data
  • Router work on more than one broadcast domain while in bridge work on a single broadcast domain
  • A protocol must be used TCP/IP, IPX/SPX, Apple talk while including transparent bridge and translational bridge
  • Router communicates with other routers to decide the best way to transfer the data while in a bridge with the help of MAC addresses of the devices the bridge listen to the network traffic and then decide the way to how to send the data
  • A router uses a software configured network address to determine the address while Bridge determine the destination address with the help of the MAC address of the device
  • The router creates basically multiple paths to send data, but in a bridge does not create multiple paths to send data
  • A router can configure such as RIP, IGRP, OSPF etc, while bridge cannot configure any routing protocols in a bridge
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Advantages and disadvantages of bridge in networking

A bridge network is a basic computer networking device which creates the aggregate network from multiple communication networks or different segment network. Here this article gives information about the advantages and disadvantages of bridge networking or benefits and drawback of network bridge network to better understand this topic. 

Pros or Advantages of bridge networking:

  • It reduces network traffic with minor segmentation
  • It reduces collisions
  • Bridge connects similar network types with different cabling
  • Bridge increase the number of attached workstation and network segments
  • It extends the physical network
  • Bridges also can reduce network traffic on a segment by subdividing network communications
  • It connects different architecture
  • Bridges network can extend a network by acting as a repeater
  • It helps in an extension of physical network
  • It creates separate collision domains. Hence it can increases available bandwidth to individual nodes as fewer nodes share a collision domain
  • Some bridges connect network having different architectures and media types

Cons or Disadvantages of bridge networking:

  • It does not filter broadcasts
  • It is slower compare to repeaters due to the filtering process
  • It is more expensive compared to repeaters
  • Complex network topology, it can pose a problem for transparent bridge
  • A bridge is more expensive than repeaters or hubs'
  • Does not limit the scope of broadcast 
  • Does not scale to extremely large network
  • Buffering and processing introduces delays

Advantages and disadvantages of zener diode

We all know that the Zener diode is a unique diode that allows the current to flow in one direction like a regular diode but is also permits it to flow in the opposite direction. It allows the flow in the opposite direction when the voltage is above some certain value as the Zener voltage. Zener diode consists of a highly doped reversed biased, p-n junction diode while operating in the breakdown region. Here this article gives the advantages and disadvantages of the Zener diode to better understand this topic.

Advantages of Zener diode:

  • The Zener diode is less expensive than another diode
  • This diode can be used in regulate and stabilize the voltage in a circuit
  • These diodes have a high-performance standard
  • Control the flowing current
  • Compatibility and obtainability
  • It can be used in a smaller circuit that would not work with any larger form of the current regulation.
  • They are compatible with the most system due to their lower cost and greater control

Disadvantages of Zener diode:

  • Zener diode cancels out voltage by applying an even larger voltage in the reverse direction wasting electricity in the process.
  • A Zener diode has a relatively poor regulation ratio and is generally not as good as the transistor.

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