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ny Professional could write equations for IRF510 MOSFET for Id=30mA;Vo=5;Vdd=9?

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10Ghz

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any Professional could write equations for IRF510 MOSFET for Id=30mA;Vo=5;Vdd=9?

guys i had spend more times on how to determine the drain current exactly using
the prefer equations , but I failed i think the problem comes from extracting the correct
Kp (constant of mosfet)
any one can put here in details how to calculating + writing the procedures&equations
step by step; please help me find Kp to determine the current i would like
please please ..............etc
extremely; DATASHEET did not including Kp;Ids(on); only they mentioned Rd(on)
WHY;;;;;;;;;;;;;;;;;;;;;;;;;;????????????????????? ???????

ok here my tries :=
IRF510 Datasheet including this INFO:
gfs = 1.3 @ 3.4 A and sometimes in other datasheet 1.3@4 A. & VgsOFF=4V
i do not know what if that gfs is same as Kp or gm ;
i assume it is gm ; thus:
as Id = Kn (Vgs - VgsOFF)^2 .............................. (1)
also
gm = 2 root (Id * Kn) then ---> Kn = (gm)^2 / (4 * Id)
apply this equation yiald: Kn = (1.3)^2 / (4* 3.4) = 124.5 mA/V^2

the required ( given ) parameters are : design MOSFET with Id=10mA with output = 5V
Vdd=9 V ; with using the voltage-divider ... here i want not to includes Rs ( resistor at
source ) .
as Vdd= Vds + Id*Rd
thus Rd= (Vdd - Vds)/ Id = (9-5)/10mA = 400 ohms
at this point all things correct right? theoretically YES yes yes
then as Vgg = Vgs
Vgg = Vdd * (R2/R1+R2) = Vgs
multiply both denominator and divisor by R1/R1 gives :

Vgs = Vdd * Rbb/ R1----------------------- (2)

for MOSFET :
for Id-= 10mA ; assume R1= 10K then
using Equation (1) yiald: Vgs = root(Id/Kn)+VgsOFF = Root(10/124)+4V=4.28 V
Assume R1 =10K
using Equations (2) and solve for Rbb yealds: Rbb = (4.28/9V) * 10K = 4759.9 ohms

and as 1/Rbb = 1/R1 + 1/R2 -----> thus R2 = 1 / ( 1/Rbb - 1/R1) = 1/(1/4759.9 - 1/10K)
thus R2 = 9083 =~ 9K ohms

THE RESULTs :
Id = 10mA
Vgs = 4.28 > VgsOFF (i,e MOSFET is ON )
Id = 10mA @ V0 =5v for Vdd = 9 V

The DISASTERs :
when apply the design on LT-Spice it is not success WHY WHY WHY ....

PLEASE ANYONE GIVE ME AN ANSWERS

YOU HAVE TO LOOK THAT I FORETHOUGHT ( DELIBERATE) NOT TO INCLUDE RS IN MY DESIGN FOR ANALYSIS PURPOSES
SO PLEASE CALCULATE WITHOUT RS
 
Last edited:

Dear Friend!
Hi
Would you like to find Drain current at linear region?
Best Wishes
Goldsmith
 

Dear glodsmith ;;
no,it's not . it can not be to find Kn @ linear region . but in active region.
the problem sir that how to find the exact Kn constant to biasing the gate the correct voltage that produce my required Id
 

Dear 10GHZ ( what the high frequency are you !!!!!!!!!:lol:)
my mean by linear is active.
though , attach your circuit here , please. when you said R1 or R2 or RS , how should i know that what kind of biasing circuit
is your mean?!!
Respect
Goldsmith
 

Hi goldsmith
i'm so glad about your reply , You make me respect to you very much
emmm about linear I see that at ohmic region the curve go to be linear proportionality (Vds-Id) . thus at saturation / active region the curve go to be straightforward and Vgs is constant currect.However that is not our point to talk about it

In datasheet i see gfs parameter . so for what it;s useful for me ? i had build many types of oscillators and i wrote about how to calculate every types mathematically and practically.but when i reached to my final stage in my book,in my lab i encounterd the problem on finding the exact value of Kn very clearly.so i thought i must find someone to supply me with
the best ways and methods to write it in my lovely book

Two parameter make me confuse in datasheet (gfs;Rd(on)) so please give me your feedback

about what frequency i'm operated on ...huhuhu. at yet i reached to 900MHz but after i finishing my Mixers&doubler chapter
I will broadcasting to you that i reach 10Ghz ; I feel i will (LOL)

thinks for your kindness:razz::


Best wishes:
M.Khadidos
 

Finally I reach to truthful on MOSFET parameter Kn:lol:

First i have to think both my friends Mr.J:lol:eek:ny130 & Mr.Adjuster in ALLABOUTCIRCUITS Forum
for helping me to reach to the truthful of MOSFET parameters so after apologies to the mentors
of this forum let me please but this link to my thread of another forum for reference only

any Professional could write equations for IRF510 MOSFET for Id=30mA;Vo=5;Vdd=9? - Page 2 - All About Circuits Forum

so it is useful for the researchers here to refer to this subject to take into account the real info about MOSFET importants parameter that must be extracted to design your own Favorited circuit
 

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