In this lecture we will continuing from where

we left off in the last one where we have discussed the two products the receiver radio

receiver AM and FM and modem. And the AM and FM receiver where only discussed transmitter

now discussed whereas modem contains in a way if it is wireless model it will contains

the same transmitter as well as the receiver architecture right it will have modulator

for transmitting and demodulator for receiving. So that is special trans receiver architectural

part that forms different end of most of the PC’s today. Now ahh today’s lecture we

will continue with ahh the other two products that we had mentioned cellphone and ECG recording.

Now let us therefore consider first the cellphone I think this is one product which has now

becomes so common that even the common man knows about the terminologies and the electronics

little bit about electronics that goes with cellphones that is the fortunate part we have

educated by making the product become popular educated the public. So let us briefly go

through the ahhh functioning of the cell phone. The most dominant product of the present day

world most impressive performs in terms of utility and also misuse. When utility is becomes

important it is also likely to be highly misused. Is basic function is to make and receive telephone

calls over a radio link while moving around a wide spread geographical area. It connects

to a cellular network ahh this is a very basic concepts there is a transmitter okay where

that is located near your area okay and there are such transmitter spread all around the

city so that it is a cell like structure. So when moves from one cell to the other the

it smoothly changes over the other transmitter to the other transmitter so this philosophy

has been used in this cellphone trans-receiver design they are also support divided variety

of the services which as text messages multimedia messaging email internet access short range

wireless communication infrared and Bluetooth. Business application, gaming, photography,

ahh music, playing all these are special features of these cell phone. Mobile phones that offer

these and more general computing capabilities are referred to as smart phones and the smart

phone is now replacing almost all these computers and ahhh ordinary phones. So cellphone block

diagram comprises of radio for transmission and reception is also part of it radio transmitter

and receiver. Now we have ahh the transmission occurring in analog domain most of the time

and therefore communication occurs in the analog domain and it is conversion from digital

to analog that takes place analog baseband okay and digital baseband we have classified

it as from the analog it gets converted to digital. So this is the general architecture

of a cellphone ahh this is ahhh block schematic indicating the analog front end and the analog

back end with the digital signal processor ahhh primarily acting for collecting the ahh

digital information and also transmitting the digital information and ahh the control

signals allocating the control signals. We have ahh the front end we have a diplexer

here ahh actually the transmission is a done at one frequency and the reception is done

at another frequency and this is the common unit with links it to the antenna both for

transmission and reception. So we have facing the path of the receiver just like any other

receiver the RF front end here then the mixer converting the RF to IF this we have seen

in the radio receiver also and I is the IF amplifier which is also filter okay. And that

output is demodulated okay and request the help of the local oscillator which is tunable

micro control is there to this to adjust the frequency corresponds to the RF that is getting

received. So ahh the baseband signal that gets generated here okay is going to the ahh

the A to D convertor here and then it is stored or played or displayed all those things are

going to take place from this than on the other side whatever information that is stored

or communicated that goes from the digital to analog for the modulated which also get

the help of local oscillator to convert into the higher frequency and that is shifted to

the RF that is prepared for transmission. So you will see that the front end remains

almost similar to what we had already discussed earlier and here the micro-processor controller

also is interacting with the human interface where is the switch board dialing memory and

battery power control. So these are all the analog inputs that are given at this point

for the micro controller now the digital thing is dealing with baseband signal like speech,

video and data okay. So you can see that this whole thing is the digital signal processing

activity here including that of this. This is the typically fashion of the present day

electronic system the future electronic systems will comprise of mainly digital signal processers

helped by the analog front end and the analog back end which are also micro-processor control

and ahhh all the control signal comes from the lower frequency digital controllers. So

this is the explanation for most of the thing that we have already mentioned RF front end

so typical path RF consist ahh diplexer tunable band pass filter RF low transmitting power

of cell phone is about ahh 500 mill watts. RF filter in the transmission path is tunable

and a band pass filter antenna is connected to a transmitter and receiver through a diplexer.

Receive noise ahh receiver noise amplifier LNA it is normally called this is in the other

path this is part. IF block the output of a LNA goes to the mixer to generate a AF signal

with the help of the local oscillator and this under the control of digital baseband

processor to produce a sensorial signal at RF + IF. The IF signal is amplifier by IF

amplifier which is fixed frequency band pass filter IF amplifier output is a demodulated

okay and I think this is a sort of omega RF okay – the digital baseband is going to

be at ahhh let us say the baseband frequency and it is facilitated by multiplying with

omega RF + omega IF. The omega IF signal is amplified by IF amplifier which is fixed frequency

band pass filter the IF amplifier output is demodulated using local oscillator which is

down converse the signal to analog or digital baseband. So analog backend and baseband the

out of the demodulated may represent the digitally coded reach video or data. The video signal

or speech signal or reconstructed using convertor the digital data directly goes to digital

band processor the output from the IF amplifier whose input is from the modulator is up converted

to the video frequency of transmission by a mixer and power amplifier before the getting

connected to the transmitting at. Speech and video signals generated by the user are converted

into the digital data using A to D convertors. Digital data goes to the modulator and to

the digital base band process. So these are the functions of the various blocks of the

cell phone. Now this is an important block power management as you see that most of the

time in order to ahh improve yield reliability in IC fabrication of these VLSI structures

these are mainly made as single chip solutions okay and ahh power management in this single

chip as to occur in terms of isolating the power supply for the digital primarily from

the analog one. So that there is no interaction between analog and ahhh and digital systems

due to parasitic capacity coupling or inductive coupling. So this is kind of thing is made

possible by efficient power management not only that efficiency of the system improves

if he shuts of those units that are not working at any one given time. So this also is managed

by digital control so basically now a days all the analog systems that are necessary

for an electronic system get controlled by the digital controller of the whole systems.

So it is digital controlled analog sub systems okay

this is what we have to study okay. Now we come to the other important system health

wise health monitoring has now part of cellphone activity so many things have been integrated

into the cellphone that the future perhaps request only to the cellphone or most of the

applications let us therefor look at the system that forms elector-cardiogram is a non-immersive

procedure for recording of electrical activity on the body surface generated by the heart

okay. So ECG or EKG shows series of waves that relates to the electrical impulse of

heartbeat that everybody knows now. So these is a typical pulse generated by the heart

this is called P this is QRS and this is T. It has features defined as PQRS and T for

each heartbeat the amplitude and relative timing of this various segment are used for

diagnosis of any heart ailment. Important components of ECG heart rate that is the frequency

about few hearts which means so many beats 40 to 30 beats per minute right. P wave is

of frequency about few hertz again this is few tons of hertz QRS and T wave is again

few hertz. High frequency potential of the order of 100 to 500 hertz for more refined

understanding of the ECG wave form. The other components which actually abstracts from ahh

getting the complete ECG function corresponds to the muscle activity which is also is around

the same frequency 5 to 50 hertz respiratory activity which is of very low frequency 0.1

to 0.5 hertz 8 to 30 beats per minute external electrical noise. This is the main enemy of

for the ECG capture 50 to 60 hertz is remains. So most of the power line frequencies components

which are close by also transmits this okay ahh electromagnetic radiation and it does

of very fast kay because it is very low frequency however because of the power at the strength

that is picked up by the body is considerable. So will depict this later on pictorially other

electrical activity is greater than 10 hertz muscle simulators strong magnetic field pacemakers

etc also interfere with this. That is a glimpse of what noise in ECG recording it uses several

electrodes and the primary thing is that it must be a differential pickup. So that common

more noise voltage which is primarily 50 hertz line pickup gets cancelled simply because

of the differential measurement. So this is the technique of putting of electrodes in

such a manner that noise gets filtered not cancelled. The machine detects and amplifies

the electrical impulses picked up by electrodes that occur at each heartbeat and a cost them

on to a paper computer or any story that is the function of the ECG recording. So it is

simply picks up this okay and this is to be recorded in paper or a computer or stored

in a storage device. Now this is where you see as differential recording this is very

important till present day electronics I would like to just highlight that the technology

of IC fabrication has made a great impact in electronic circuits what is that the technology

of IC fabrication has made as realize absolutely symmetric networks which means it is going

to facilitate easy cancellation of common mode noise this is the greatest thing that

is happened in IC fabrication. This kind of thing never existed in discrete circuit fabrication

and this is how we get rid of the noise problem here by using a differential recording. So

ahh this two points okay and these two voltages are measured with reference to a common point

okay and therefore the common mode will take gets picked up here hopefully okay is very

well you call and then gets captured. Obviously it is possible that it is equal and that is

some amount of this 50 hertz noise stay guess picked up of the fact that these two points

are okay not exactly having the same voltage what respect to this common point okay. So

this has nothing to do with the electronics but the electronic device that is going to

be used as the front end here as to be a differential amplifier that is obvious to ever body. So

that is the technique of noise cancellation differential recording between two points

on the body amour. They have defined as V1, V2 and V3 okay so this is the arrangement

of electrodes. And you can see get an idea of the signal the common mode noise that we

are talking about to solve. This are the order of flow volts 1.5 volts okay and the offset

due to the electrode placement is of the order of 300 milli volts that is therefore going

to pickup the 50 hertz noise and then the ECG signal is on the other few millivolt occurring

at these frequencies. So this is the signal that we have to pick up earlier in the first

lecture I had shown you how the ECG signal looks like this predominant common mode noise

that got picked up inspite of being differential. Now these are the blocks that form the ECG

ahh so we have a multiplexer here so we place is instead of just to ahh sort of electrodes

we place multiple set of elect pairs of electrodes to find the voltage at different point and

multiples these data and take an average and this is the best technique to eliminate the

noise as well as get the good value of the actual ahhh heartbeat okay. Instrumentation

amplifier is a differential amplifier which is an IC that we can fabricate it is a symmetric

structure will let us see and then we have a variable game so as to adjust the output

so as to make it compatible with that of the data converter that we are likely to use after

that we have the high pass filter, low pass filter high pass filter to eliminate high

frequency ahh. White noise mostly low pass filter to eliminate very low frequency noise

which is interfering with the ECG ahh and then not filter to primarily get rid of the

50 hertz or 60 hertz and then final amplifier only most of the amplification is concentrated

here so that it is after all the removal of the noise that is signal gets amplified then

it is processed after it is converted to digital by the DSP and stored displayed or recorded..

So this explains what I have just now indicated inputs from groups of electrodes are multiplexed

and processed for the common mode rejection by the instrumentation amplifier the output

of the INA is amplified and variable gain amplifier gain is adjusted so that output

becomes compatible as that of the ahhh amplifier okay and the data convertor. Frequencies below

0.5 hertz are eliminated by the low the low pass filter or high pass filter as a low pass

filter and above hertz are emitted by the low pass filter and 50 hertz is eliminated

by the notch filter. The output of the noise filter is amplified and coded to digital form

using A to D convertor the digital data is suitable for processing by a DSP for recording

this display or storage. Now we come to the basic analog signal processing function that

are required in all these ahhh functional blocks or gadgets electronic products that

we have discussed amplification what does it mean attenuation or amplification. Mathematically

this simply means okay multiplication by a constant. This is multiplication by a constant

alpha times let us say X, X is the independent variable in this case or current it does not

matter so if you can multiply alpha if alpha is less than one is called attenuation it

is called attenuation if alpha is attenuation. If alpha is greater than 1 it is called amplification

filtering that means getting rid of noise if it is within the band you will use what

is called a notch filter if it is for within the band noise outside the band high pass

low pass or band pass outside the band high pass filter low pass filter or band pass

filter this noise filter is band stop filter these are the common filters that are used

in most of the signal processing right. What is therefore then comparison you are comparing

either a voltage or current with a reference compared with the reference. Now this is nothing

a but a mixed mode circuit this are purely analog here the input is analog output is

digital input is analog and output digital this is for this multiplication it could be

what both analog okay then it is called modulator mixer and all that. 1 analog 1 digital then

it can act as multiplexer analog multiplexer it can select the analog

signal that want to input to the PC of something like that. So you give one analog comes if

we give 0 nothing comes from this right so when you actually 0 to 1 analog we can apply

1 to the other analog okay. So that other analog gets the selected that is what is called

multiplexing so multiplexer is multiplier operation okay. Then both digital then it

becomes an X or gate exclusive or gate these are the varities of

mathematical operations that go with signal processing you can see a wide area of signal

processing getting covered just by these operation. A to D conversion A to D we have already talked

about this example of this is nothing but a comparator which we already discussed here

as a 1 bit A to D convertor comparator is a 1 bit A to D convertor DTA convertor is

nothing but sigma let us say A analog=sigma 2 to power –N V reference into AI, I=1

to ya so we have a young bit DTA convertor so I ranging from 1 to N you nothing but a

analog the reference is analog and this is digital. A digitally controlled analog output

you can get a multiplier you can get again one input is analog and other input is digital

so DTA convertor is treated as a multiplier where one input is analog and the other is

digital just like multiplexer. So these are the basic things activities that get carried

out and these are explained in detail further. So we see here the tail thing about amplification

let us discuss this output is either a voltage or a current in an amplifier since the variable

can do voltage or current output can be available as a voltage or current then that is equal

to K times input which is voltage o current + some offset which is independent of input

that is called an offset it can be current offset or a voltage offset that depending

upon what the output is so the K as to be greater than 1 if it is amplifying okay if

it is attenuating is less than 1 now this becomes a control source okay. Voltage control

current source voltage control voltage source so we have voltage control we have voltage

controlled voltage source voltage control current source current control voltage source

current control current source. So we have four combinations of this amplifier becoming

possible theoretically there are no further amplifier possible. So the basic definitions

have to be understood very clearly first before we venture into any signal processing activities

and this is the basic degree. We have a voltage amplifier a current amplifier and then the

trans conductance amplifier and a trans resistance amplifier that is possible theoretically with

this kind of definition next is important that he should be able to amplify a differential

voltage that I have already indicated when we discussed about transducers that means

it is not a single ended voltage amplification it is X1 and X2 as the two independent variables

there may be B1 and B2 when they are voltages. Then theoretically any linear system will

give you an output corresponding to X1 and X2 so that can be categorized as what is not

wanted is that corresponding to X1 + X2 by 2 this is called the common mode signal and

X1 – X2 is called as differential mode signal this signal alone is important to be amplify

in a differential setup and this signal has no place at the output. So ideal differential

amplifier or difference amplifier so give an output corresponding to only the difference

X1 – X2. However linear systems if it is design then there will be output corresponding

to both the inputs and they may not be equal if they are equal okay then it is a differential

amplifier if it not equal because of some mismatch because of non symmetric because

the circuit that is processing it is not exactly ideally symmetric then what happens is that

this common mode signal appears and there is an error. And therefore output normally

is proportional to the differential signal into some KD this is called the differential

amplification factor and KC into X1 + X2 by 2 which is the common mode signal and this

KC should be ideally speaking in the symmetric structure that is amplifying it should be

0 in practice of course it is not 0. So where KD is known as differential mode gain and

KC is known as common mode gain KD by KC is the measure of the quality of the this difference

amplifier and that is measured by a parameter called Rho this is called common mode rejection

ratio. It is normally expressed in terms of decibels as 20 log rope and ideal difference

amplifier to the have common mode rejection ratio equal to infinity that is because KC

should be 0 for it. So KD by 0 is corresponding to infinity as far as Rho which is called

common mode rejection ratio which is normally called CMRR. These are gain definition that

should learn about before you understand the technology or fabrication of any active device

or an amplifier. So we come to the important section of filtering we have all been familiar

with coffee filters does the same thing that electronic filter does it selects what you

want to select right that is the liquid coffee as a liquid and the solid portion is retained

so same way the solid portion that is retained is the noise I should not come okay so the

liquid portion is what you want to accept and drink okay. So the signal bandwidth is

the one that has to be permitting the signal to appear and reject the noise so filter is

for rejecting the noise and accepting the signal in various bands of these signals filter

can be as I pointed out earlier low pass to remove the high frequency noise high pass

to remove the low frequency noise band pass to remove the low frequency and high frequency

noise band stop to remove in band noise which is dominating. When you remove the in band

noise knowledge so happens that you have to sacrifice some amount of information because

it also remove the wanted signal. Low pass filtering is going to be depicted this way

ideal low pass filter is a box like that is do not want any component corresponding to

frequencies beyond this okay. So above this bandwidth this is corresponding to the wanted

signal bandwidth for example if it is audio and high fidelity music we want to collect

then you would restrict about 20 to 30 kilo hertz that is the bandwidth over which you

would accept this signal and reject this other high frequency signal okay. Now non-ideal

low pass filter that is what is practically realizable okay this is practically non realizable

will give the reason later but for a single input we have a multiple output possible so

anything that is having for single input multiple output possible is physically not realizable

okay and therefore we have to approximate this filter to ahh something better where

for every input that is unique output that is what is physically realizable and these

filter for example are going to be the low pass filters that we will realize later using

the available components. Now high pass filter that we want to detect below frequency noise

the low frequency noise corresponds to drift of a voltage because of temperature dependence

mainly latency or any temperature dependent activity result in this kind of okay drift

in voltage and therefore that results in the offset voltage drifting in all the voltage

or current and that has to be eliminated from the signal and that can be done by introducing

what is called as lower cut off frequency okay below this the noise gets eliminated

and above this the signal is going to be passed. Now this is the box like approximation for

a band pass filter the bandwidth of the signal let say is corresponding to this. For example

this is an IF filter so around let us say 455 kilohertz maybe the center frequency is

located and then the band width corresponds to ahh 20 kilo hertz on either side of the

center frequency okay so that we want to receive high quality music okay. So 40 kilohertz is

the bandwidth and 455 kilohertz is the center of the frequency we can design a filter not

exactly having this characteristic once again it has to be approximated it can better approximated

by this kind of thing or in this case if you have a really troublesome neighbor hood frequency

that let us say worth your cellphone is transmitting and this is the neighborhood frequency okay

where the power is more than if you design this kind of filter that power that will come

into the your phone will be much more than your own power. So you will not be able to

hear what you are friend is talking okay but you will be able to hear the neighbors talk

okay which is a noise right. So this is the trouble so what do you do you kill that fellow

by introducing a 0 of transmission fee that is not transmission at all that is going to

be received by you so this filter okay can be realized later on will see and therefore

this particular transmitted power killed here and here okay. So you locate of this kind

of 0 of transmission okay wherever you have high power neighborhood frequency is interfering

with your signal okay. Now same thing can be for a band of frequencies here again this

box like approximation is not accepted we will do an approximation of this okay either

this way or this way to get rid of a band of frequencies okay. Now comparison simply

means like that let us say we have an input voltage coming like this and this is the reference

our comparator which maybe voltage comparator or current comparator as two inputs where

this voltage is the incoming voltage and this is the reference voltage what happens to the

output as long as let us say the input voltage is growing greater than the reference voltage

output goes negative the just gives this a digital 0 this is negative means let us say

0 some voltage. And if the input goes below the reference it goes positive so as the output

of the comparative is concerned is as there is only two states high and low okay that

going from high to low or low to high occurs exactly at voltage reference or a current

reference depending upon the input chain this is something that is very very important in

signal processing this converts the amplitude information to width information. If you call

this as duty cycle over a period then duty cycle gets varied as this voltage reference

is filled so you can convert an amplitude information to width information these are

called pulse width modulator okay. This width information conversion is possible and this

is having a important application to AC to DC convertors such the switched motor power

supplies class two power amplifiers and this is a very simple concept or understand okay.

Now we come to the last application we are going to discuss that is multiplication the

output of the multiplier is the product of two inputs let us say we are talking of voltage

multipliers it can be current also where I naught=K naught into I accent IY here we

are depicting we have depicted voltage multiplier V naught is K naught into VX by VX into V

naught. In precision multipliers this is with work for + – 10 volts okay is therefore called

as four pattern multiplier + – 10 volts okay. So this can work all the way from – 10 to

+ 10 for these voltages and the maximum output to the multiplier itself adjusted by adjusting

cannot as 1 over 10 volts if you make this constant as 1 over 10 volts then output of

the multiplier will never exceed 10 volts that is the standard precision multiplier

design. So this interesting fact that this is going to cover of the communication applications

the basic principal which can be taught to anybody any engineer because the mathematics

of this is very straight forward and simple a non-linear multiplier will have a relationship

obviously now we are not be independent of both inputs that is called offset voltage

it is having the component which has nothing to do with product of VX and VY but only dependent

upon one of the inputs VX or VY these are called components these also should be absent

in ideal multiplier. So KX has to be 0 KY has to be 0 V offset as to be 0 okay in an

ideal multiplier. In an practical multiplier these may not be exactly 0 these have to be

adjusted to be 0 later on okay + of course the non-linear components corresponding to

the X square and other non –linear higher order non-linear components can also exist

by properly selecting the typology of the multiplayer okay we can actually get the multiplier

to be precisely this okay. Let us therefore see the application of these multiplier okay

in communication. So I am the example of this multiplier now V naught=K naught into VP1

sin omega 1T X is VP1 sin omega 1 T and other one VY is VP2 omega 2T. So then what happens

output is K naught VP1, VP2 by 2 Cos A – B omega 1 – omega 2 T okay this is not + actually

it is – Cos omega 1 Cos omega 2T okay. So this is called double side band you can see

two side bands omega 1 – omega 2, omega 1 + omega 2. So this is called double side

band okay modulator balanced modulator it is called and mixer so this may be the RF

+ IF and this is RF then you will get the difference components which corresponds to

you that is how in the mixer you will get the IF and this will correspond to then this

omega twice omega RF + IR okay. So it is a higher frequency component by using a band

pass filter that is IF filter you can select this you can reject this as the operation

of the mixers let us finish. So V naught=K naught into VP1 sin omega 1 T and VP2 sin

omega 2 T into that is nothing but modulated VSP you multiply it again the modulated DSP

modulated output is VX and VY correspond to 2 Sin omega 1T okay then what happens you

get here K naught into VP1 into VP2 by 2 into 1 – Cos 2 omega T because that is because

this is Sin square omega T which is 1 – Cos 2 omega T by 2. So you get rid of this higher

frequency component by using a low pass filter okay then you will get an output okay which

is a sort of DC okay that is the modulating frequency components this is a demodulator

omega 2 is the modulating frequency component you get that bass band signal so this is the

down convertor or this is the bass band signal extractor demodulator it is called DSP modulator.

So you can see that same multiplying function depending upon the input acts as mixer or

demodulator. Now if they are not same frequency omega 1=omega 2 they might have a face different

so this is sin omega T this is sin omega T + 5 then modular get came up B21 B22 by 2

cos 5 the difference and some 2 omega T + 5 this can be got rid of using a low pass

filter you get the DC dependent upon the phase shift. So this is known as phase detector

if you get rid of this if you get rid of this then what remains that is by using a high

pass filter okay you can get rid of the low frequency that is DC and select this and then

this is a frequency develops okay. So this same structure acts as a phase detector a

frequency table that means from you get 2 omega from 2 omega multiplied by another omega

you can get 3omega so you can generate all the harmonics by using this process of multiplication.

So it is used for frequency synthesis right so it is a powerful unit this process of multiplication

is a powerful unit for obtaining most of the communication function okay except for linear

that is amplification okay if you actually make one of the voltages DC it becomes a voltage

controlled amplifier this is BCE what is means is VX is let us say VC okay than what happen

output is K naught VCP into VP2 Sin omega T so you get this signal VP2 sin omega T getting

amplified by this factor and it can vary this by changing VC. So it is a voltage controlled

amplifier okay we used a music synthesis and all right so this is one of the most powerful

IC that can be understood okay by anybody and used in ahhh practical laboratories to

understand the basic communication principles. This is what we have already explained digital

to analog conversion for input is a N bit digital data and the output is an analog signal

up. So we have this signal as I=1 to N AI 2 to the power of – MV where AI is either

1 or 0 so that is nothing but the output of a young good digital data it can also analog

output of A and with digital. It can also be called a multiplier with V reference as

a analog input and A1, A2, AM is digital but is the digital signal. A to D convertor the

output is N bit digital data and the input is analog signal a comparator is 1 bit A to

D convertor. A comparator is normally represented as a voltage or a current competitor now signal

generation you come to again one of the basic principles which you have studied in your

plus 2 okay this second order harmonic equation it is called del squared V instead of Y I

am using V here voltage del T square + KV=0 this is second order differential equation

with first order being absent this is called the harmonic oscillator equation which all

of you have studied here plus 2. The solution of this differential equation V=VP sin root

of K into K + 5 omega=root K is the radiant frequency at which this will give you an output

a synthesized output. The depends upon the initial condition so this is the basic principle

used in ahhh generating any sin wave in electronic also this principle is used okay. So all our

sin wave generator which are needed for test oscillator ahhh simulation this are generated

by simulating this equation. So any system that generates sin wave as to simulate this

equation so power supplies forms the last part of the subject but the most important

part also so here we are going to be dealing with switched motor supplies which are the

most efficient power supplies okay and ahh they reduce this eyes of the component parts

to such an extent because of the high frequency of switching and we have also what are known

as low drop out regulators okay which are most important topics to be discuss in power

supply design okay. These are purely analog however these are going to be controlled in

power supply management which is an important part of system design. So power supply management is an important part of power supply design

which is going to be done digitally so micro controllers and DSP’s can be used efficiently

to control the power supply so that efficiency of the whole system is maximum. So we have

in conclusion discussed the cellphone and the ECG architecture wherein all these 4 products

that we have discussed emphasize one point the communication is always carried out in

analog. Communication in future may occur within the chip just forget about outside

the system right outside the system communication is already happening in analog interms of

problems being used in terms of RF front end being used and ahhh therefore the communication

outside the systems domain as already come into existence. In analog communication is

likely to take place within digital system itself to talk to various digital blocks which

are occurring in the system the wired connection or the line connection okay is going to be

the communication denser and denser and therefore it will be ultimately wireless connection

within the chip most probably is the trend of feature so analog as to be that there is

no way out. So let us learn this okay in the future lecture basic principles of analog

signal processing is going to be emphasized from system design view point. What are the

analog system that can be realized using this basic blocks that we have already emphasized

okay. So the IC design which will involve the transistor may be mass today okay is going

to be a higher level course very few offers are going to be involved in IC design just

like DSP design is going to be done by very few people but DSP usage has to be learnt

by every engineer today right. Likewise understanding analog IC’s and usage of analog IC’s is

something that everybody as to understand first before ahh sort of specializing in IC

design this kind of term is going to be a beginning of understanding VLSI.