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guide me to design te aspect ratio

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puush

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hi...............
how to calculate the aspect ratio for transistor????:cry:
 

puush

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you are using single transistor circuit ?????????

you must tell the circuit

sir.. actually im doing my final year project on design of pipeline architecture using cadence:).. so i need do design the sample and hold circuit.. i have some references and the circuit diagram of this project;-).. but i dnt kw how to proceed without knowing the design of aspect ratio..:roll:

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you are using single transistor circuit ?????????

you must tell the circuit

sir.. actually im doing my final year project on design of pipeline architecture using cadence:).. so i need do design the sample and hold circuit.. i have some references and the circuit diagram of this project;-).. but i dnt kw how to proceed without knowing the design of aspect ratio..:roll:

- - - Updated - - -

you are using single transistor circuit ?????????

you must tell the circuit

"sir.. actually im doing my final year project on design of pipeline architecture using cadence:).. so i need do design the sample and hold circuit.. i have some references and the circuit diagram of this project;-).. but i dnt kw how to proceed without knowing the design of aspect ratio..:roll: "
 

Dar89

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A very pragmatic method, if you know the behavior of the circuit, is sizing the transistors with a W multiple of Wmin (L is minimum, if there aren't particular reasons), making a coarse sizing. Then you can adjust (in function of your constrains) the aspect ratio with parametric simulations using cadence.
 

puush

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A very pragmatic method, if you know the behavior of the circuit, is sizing the transistors with a W multiple of Wmin (L is minimum, if there aren't particular reasons), making a coarse sizing. Then you can adjust (in function of your constrains) the aspect ratio with parametric simulations using cadence.

i kw the behaviour of the circuit:-|.. since im using a differential SHA(sample and hold amplifier). i need to kw the aspect ratio(w/l) :sad:for each transistor to draw the schematic and simulate it to get the out put.. and there is a switch in the circuit diagram which has clock and vss which resembles the relay:???:.. can i post the circuit diagram..??????:!:
 

prestonee

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You need to know what you are designing it for, as in in performance specs. typically you can get any analog circuit to work no matter the ratios. the ratios come into play when trying to achieve required performance constraints. how fast, max slew allowed, how much loading, max ktc noise, and power..
 

puush

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hai... sir!!!! are you free???

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sir... I want to carry out the design of three stage comparator which is provided in the book cmos circuit design,layout and simulation.. part iv mixed signal circuits ... in this i have to design the comparator circuit... how can i get the standard values for constants .. Iam using cadence 180nm tech in cadence using spectre tool version bsimv3... can you guide me how to design.. the circuit consists of preamplifier,decision and post amplification.. please...
 

erikl

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Re: guide me to design the aspect ratio

Simply start with Figure 27.9 of Chapter 27 Nonlinear Analog Circuits !
 

puush

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i need to change the aspect ratio in that circuit i dont want it to be 10/2 and 3/2... i want it different.. how to calculate it??? and what are the values i should assume??? and please mention which value has to be calculatead using equations???:-?

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i need to change the aspect ratio in that circuit i dont want it to be 10/2 and 3/2... i want it different.. how to calculate it??? and what are the values i should assume??? and please mention which value has to be calculatead using equations???:-?

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i need to change the aspect ratio in that circuit i dont want it to be 10/2 and 3/2... i want it different.. how to calculate it??? and what are the values i should assume??? and please mention which value has to be calculatead using equations???:-?
 

erikl

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i need to change the aspect ratio in that circuit i dont want it to be 10/2 and 3/2... i want it different..
Why?

how to calculate it??? and what are the values i should assume???
Depends on your requirements!

and please mention which value has to be calculatead using equations???:-?
Lot of questions and no details from your side. I'd think you better study the design books!
 

prestonee

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sounds like assignment was given by a professor who said don't use existing ratios found in the example
:)
 

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