Role of Analog Signal Processing in Electronic Products –

Role of Analog Signal Processing in Electronic Products –


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.

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