welcome to unlock layouts in this video today we are going to discuss the topic of fingers and multipliers let's start the video so in this video so we are going to see fingering concept and multiplier concept so first we will go in for a fingering concept so what is the reason we have multiple fingers in one MOSFET or else on CMOS the reason is consider this is a figure 1 so we have a figure 1 here so this is figure 1 so this is a but it device this is a big transistor so we can take it this area as a width of this transistor and this one has a length of the transistor so we have a big vertical wise it's a big transistor whorls it's we can call it as a big CMOS so as I said in my earlier videos every metal having some sheet resistance every metal having some sheet resistance that's called RS so every metal having some sheet resistant see what will happen the gate metal also having some sheet resistance each and every unit square so whenever we are handling with them but it's wise it's a big transistor so the number of serious resistance will be very high because it's very but it's wise it's a very big transistor so if you want I can draw it as a normal diagram here see consider this the gate terminal so we are having some good thing so each and every unit square as I said this is having a serious number of resistance so this is a gate terminal so what will happen suppose if I am giving input voltage of 5 here each and every node so we can call it as a this is a first node second resistor is the second node third resistance is a third node and fourth resistance is a fourth row and philistinism so each and every node see this is a each and every node we are losing some old age but the current remains same so there is no loss in current only voltage so for example here between these voltage between these first resistance we will get some 4.9 older second time second resistor we'll get some 4.8 so etc etc etc etc so last transistor we will get around 3 older so it depends on the resistance value it depends on the sheet resistance of the metal so depend upon the shield resistance of the metal every node each and every node so this first node second or third node every node I am lossing some voltage same thing happening here also what will happen suppose if the length rise sorry if the force of good advice if we are handling very huge MOSFETs are used transistor each and every node I am dropping some voltage every node I'm dropping some voltage so due to this what will happen same situation consider I am giving the input voltage of 5 volt so the first resistance is getting sufficient VD because first Westerns we won't get so much of voltage drop so first resistance will get sufficient VD so what will happen from the source terminal to drain terminal we there will be a conduction so current flow will be there so second resistance so consider second resistance here also suppose V as the second destined to achieve some maximum VD second resistance also will get some voltage conduction from source area to drain area so everything is a single MOSFET area I am telling third transistor consider here 50 percentage of the voltage you last year 50 percent Innocents 2.5 volt you lost 50 percentage of voltage is lasting due to the series distance of the gate so somehow 2.5 is a sufficient reading these year also will get some conduction from source to drain terminal here after some particular point suppose if I am getting only 1 volt see in these resistance after this resistance particularly this point I am getting only 1 volt or below on world so what will happen in this case the transistor will be conduction happen only the particular area where the sufficient VT is the transistor is getting where the sufficient VD if the transistor is getting up to this area the transistor conduction will be there remaining this area see from here to here we have some area this area we are not getting sufficient VT the VT is full we didn't get the sufficient VD it's the voltage entire voltage I'm I dropped here suppose in this particular point I am getting only 0 old so due to the series number of resistance of the gate so what will happen 0 volt due to this series distance of the gate so I am suppose everything is an example suppose here I am getting 0 volt so what will happen to these area particularly this area so here there won't be any current and voltage conduction half of the transistor 75 percentage of the transistor will conduct and remaining 25 percentage of the transistor it will not conduct due to the voltage lagging due to the insufficient voltage from the gate terminal so these problems cannot be solved suppose if you are using him very very big transistor we have to solve the problem only in two ways first way we need to increase the input voltage instead of giving 5 volt we have to give an volt or 15 volt or in between 5 to 10 volt based on the voltage drop but the first thing we can't increase the input voltage of the gate so 5 volt input voltage is fixed because of the reason suppose due to their sheet resistance of the metal you are feeling some part of the transistor is not working so we what we are doing so we are increasing the voltage from 5 volt to 10 volt so this is our this generalities sufficient so the if suppose if you are giving ten volt the entire transistor is getting turn on but if you increase the 10 volt what will happen to the first node the first node of the transistor is getting higher voltage instead of five no it is handling ten volt so what will happen the transistor of the first node or else mass but of this first node due to the high voltage because we are giving 10 volt so due to the high voltage rating the transistor here only it will get permanently damaged sorry here only the transistor will get permanently damaged due to the high voltage so because of these reason we can't increase the gate voltage so gate voltage will remain fixed with five voltage then what about what is the ways but the way suppose if we want to if you want to run width wise it's a very big transistor or big ways it's a very big MOSFET then how to resolve this problem the one and only way to go for a fingering concept so fingering concept in the sense what we are doing instead of giving to the serious resistance II we have a serious R instead of going to the serious resistance because of the serious resistance only here we are lost in some voltage so calculate so this series resistance I am a drawing here because of the serious resistance only the old age drop is taking place here so what we are doing so we are splitting the resistance divided by two so what we are handling we are dividing the resistance this is a gate resistance so this is a gate resistance so R divided by two honey also R divided by two how we can achieving these are divided by two in the sense we are dividing their width of the transistor by 2 C this is a w first transistor W here we are width wise we are W by 2 and here also W by 2 if we but it wise if you are splicing if you are splitting by 2 obviously the gate resistance also R divided by 2 and are divided so somehow we are reduce the gate distance so the input connection should be given here so we have to give their input connection here so this is an input connection in this one metal so what will happen the voltage will come from this point to this point the voltage will split equally because in a parallel connection voltage will remain same so what will happen the voltage equal number of voltage will flow in this direction also same equal number of voltage will flow in this direction also so consider this is the first resistance is the first node the first node is getting sufficient voltage because for because first lessons right so maximum there won't be any voltage drops so first resistance is getting sufficient VT then there will be a convention and then second resistance also getting sufficient VT the current conduction will take place here say M the voltage is splitting and going to the down transistor also same the first node of the transistor rebuilding sufficient VT there will be a conduction from source to drain again one more second resistance is there from here also we are getting sufficient beauty so the voltage conduction will be there because of the reason we are dividing the width by two so by dividing the width by two we are reducing the series resistance of the gate transistor because every terminal every node having some heat resistance so we are dividing the sheet resistance so because of this reason only we are going for a fingering concept main thing so fingering concept is mainly based on the voltage related problems wherever the series resistance due to the series resistance of the metal you are losing some voltage each and every node are each and every unit square if you want to solve the problem you have to go for a fingering concept with just a fingering concept so in a layout what how the structure will be there is so this will be a source and drain terminal of transistor so we'll get two fingered innovation so this is one gate and this is one more gate this is source of the transistor or else you can take this a brain of the transistor this is a source and since this is drain off the transistor RL source of the transistor this is source of the transistor or drain of the transistor so consider suppose first turbine and if you considering source second terminal will be drain if you consider second terminal is drained obviously the last element source same thing if you then if you consider the first terminal is drain in between terminal is considered as a source and last terminal will be drain so what will happen suppose we can go it further source on source method not with the drain and right mother so the source and the source should be connected and we can take it as a common source input and these drain we can take it as a drain input and these two gates are connected and we can take it as a gate signal the series resistance we are dividing by two by dividing the width of the transistor so usually in cross sectional this is a cross sectional view in schematic wise we will get the structure of see two transistors not two transistor two-fingered a transistor same gate this is a drain terminal this one also tie in terminal this is a source terminal terminal C we have source and drain and get three terminals these are two fingered a transistor we have two gates this the first to get first gate this is second to get this is seconding it follows in one more way also we can draw consider this a shrine the source doesn't gate gates are connected together and this a common drain and this a common source so this is the concept of fingering why we are particularly going for the fingering concept whenever we are facing some voltage related problems we should go for a fingering culture because serious resistance here due to this number of serious resistance only half of the transistor or L some part of the transistors is not working due to the lack of voltage so you can't increase the input voltage because if we can't increase the input voltage because if you increase the increase the input voltage obviously the transistor performance will totally vary so we cannot increase the input voltage that is why we have to dividing the width by two and by dividing the width we are reducing the resistance also by two this is series resistance of the gate so fingering concept is particularly based on get resistance area this is regardless of source and drain resistance particularly gate resistance area we are reducing the gate resistance by going the concept of fingering concept so this is called fingering concept and second concept we are going for a multiplayer concept so this is multiplayer concept so we are going for multiplayer concept so what is multiplayer in the sense see as I said that fingering it's purely related to voltage related problem and multiplayer is multiplayer is purely related to current related problem so this is a current related problem is multiplayer so in finger we are dividing them width by 2 but whenever we are handling multiplayer the width in same so there is no dividing the width we are not dividing the width of the transistor or any way so what we are doing we are just same size of the transistor we are taking one more one more transistor same width is also same transistor and length is also same transistor there is no differentiation in width and length so this is called a length of the transistor this is length of the transistor there is a width of the transistor the same kind of the structure same width and same length we are taking one more transistor so this is called M is equal to 2 which means multiplier is equal to 2 the reason why we are going for multiplayer whenever we are handling their high current related circuit for example 5 volt and 10 milli ampere current so what about this 10 milli amps current suppose in some situation few mass transistors will handle high power or any current so high current power MOSFETs are also input output pair related things almost any MOSFET is based upon the schematic or based upon the circuit suppose if any MOSFET is handling high current rating so what will happen suppose as per the standard of 90 nanometer technology as per the standard of 90 nanometer technology these transistor can having the capacity 5 old 1 milliamps current but this is a maximum voltage and current carrying capacity after first transistor M 1 but we need to operate the transistor with 10 milliampere current we can't directly apply the 10 milliampere current to their transistor because the current carrying and voltage carrying capacity of the transistor is 5 volt and 1 amps so how this is situation then how can we able to handle the milliampere current owners the simple way by going multiplayer concept so multiplier concept consider we have a lengthy line so this is the first transistor this is the second transistor and this is the the other transistor and this is fourth transistor this is fifth transistor feiyu transistors are connected in parallel see this is a gate connection hot source and drain connection I am talking about everything it's finger and multiply later to get only not source and right so these are all the gate connection same situation each and every transistor having the capacity of 5 volt 1 Williams current we have handling 5 volt 5 milli amps current 5 milli ampere current so if you are going for the whatever is big transistor fingering raises I am talking about now finger wise suppose if you are going for the width wise bit transistor we can't the 5 volt it is not sufficient for the width wise big transistor so because of to solve the voltage really little problem we are coming to them fingering concept so now we are handling with the high current reading so what will happen in the high current reading the old age will remain same 5 volt but the current of each and every node will be divided for example if we have a fire multiplier so each and every each and every multiplayers will handle 1 milli ampere current so 1 milli ampere current and to 5 multiplex is equal to or on 5 milliamps current so each and every transistor i 1 i do i 3 and here i for a near - so we have a over all five current so in a parallel circuit usually the current will be divided but voltage remains same but in serious circuit voltage will be differ but current will be same but in a multiplier concept we are with the high current related things see for high current related fiims current we are handling with the 5 ampere current but the capacity of the single MOSFET is having the capacity up to 1 Williams only so if it is exceeded up after 1 million that the first transistor will get damaged but somehow we have to handle with a 5 milliamps current so whenever there is a current high current regulator thing then we compulsory we have to go for a multiplayer concept so this is called a multiplier concept so in multiplier concept voltage remains same each and every node the 5 volt will remain same but the current will be divided so overall current height total is equal to i1 plus i2 plus i3 plus y4 plus y5 this is overall total current is the total current is equal to 5 milli amps current so each and every node we can calculate 1 plus 1 plus 1 plus 1 plus 1 the over all collectively we have 5 milliamps so whenever there is a high current related things we have to go for a multiplier concept in multiplier concept there is no vertically divided by 2 width we are not splitting here only we are say we are what is a cm width of the size of the transits are saying what is the ways we are taking the same transistor and we are handling with the high current thing and second thing what is the thing what what is it I suppose multiplayer and finger both concept we are implementing in a single transistor multiplayer and finger we have separately watch the video now I am going to explain particularly both if the single transistor is having multiplier also and finger also see single transistor having to get same one more transistor having to get so for example five old and two milliamps current as I said earlier the single transistor MOSFET can able to operate up to 1 milliampere in certain technology I am telling about certain technology but we have to handle 2 milliamps current also this is a little bit transistor so this is a finger so w-why do if you consider normal structure it will be a double of the normal size transistor say what is the vice big transistor so there is a voltage related problem due to the series resistance so there will be a lot of series resistance due to the serious resistance we have to go for a multiplier concept but the current rating is also high so current rating also high and widthwise also big transistor so what we have to do we have to go for fingering also EF is equal to 2 and the current rating is very high we have to go for multiplayer concept and so a multiplier is equal to su to the overall size of the transistor Arlen's overall width of the transistor will be sitting there in do multiplayer for example finger is equal to 2 and multiplayer is equal to 2 we have 4 microns good size of the transistor is 4 microns so in this case we are do multiply finger also we have to multiply multiplayer also so both the cases we can go it for a multiplayer concept also separately and we can go for a finger concept also sacred separately suppose if we need both finger and multiplier should be the same concept we can implement them figure and multiplayer in the same concept also in the same schematic also it depends upon the old age rating of the transistor and current rating of the transistor and size of the transistor size in the sense mainly we have to think about width of the transistor only not length of the transistor because length of the transistor is always them always them innocence suppose if you are going for 90 nanometer technology the length of the transistor is everywhere same so we cannot change the length of the transition but width of the transistor we can change same for 45 nanometer 45 nanometer also length remained same for the 45 nanometer everywhere all the transistors will have the same but ways we can change so if you want to know what is mean by length of the transistor in cross sectional view I can explain with you see we have a source terminal we have a drain terminal and here we have a gate terminal so these area source to drain area our drain to source area is called the length of the transistor so this is mainly related to 90 nanometer 45 nanometer 28 nanometer and what about width of the transistor on C we have a such a usable of the transistor this is a serious resistance so this is the width of the transistor not length of the transistor length of the transistor is this width of the transistor is due to these sheet resistance each and every sheet resistance are unit square sheet resistance after here there will be a convention here there will be a convention and particularly this point we will not get some voltage you won't get any voltage so this particular point will not be turn on so this is the cross sectional view of the MOSFET the cross section 3 de 3 D cross sectional view of the MOSFET this is length of the MOSFET and this is width of the hospital so in cross sectional view so usually length of the transistor is related to technology ways for example 90 nanometer means the length of the transistor or length of the gate will be 90 45mins 45 45 nanometer length of the gate means we can call it as a distance between source and drain also we can take it or else eyes of the gate also we can call it as a length of the transistor so size of size of the gate is also called a length of the transistor and distance between source and drain that is also called a length of the transistor both are same so this is the multiplayer and fingering concept thank you for watching my video I hope you liked my video if you like my video please click like button please subscribe my channel if you have any doubts or queries please contact me to my email id follows on my face please kindly share this video to your friends so that they can able to understand the VLSI related concepts and one more thank you for watching my video