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

AI Thread Summary
The discussion centers on the challenges of calculating the drain current (Id) for the IRF510 MOSFET, particularly in determining the Kp constant, which is not provided in the datasheet. The user attempts to derive Kp using the transconductance (gfs) value and equations related to Id and Vgs, leading to a calculated Kn value. They outline a design for a MOSFET circuit with Id=10mA and V0=5V, successfully deriving resistor values for the circuit. However, the design fails in LT-Spice simulation, prompting a request for assistance in troubleshooting the issue without including a source resistor (Rs). The user seeks clarity on the discrepancies between theoretical calculations and practical results.
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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;;;;;;;;;;;;;;;;;;;;;;;;;;?//
 
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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
 
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