drain current noise (A2/Hz) in pspice

[dieyae16]

hi,

i'm, trying to get drain current noise (A²/Hz) in pspice. below is the example of output simulation that i have. the output only have the information of drain voltage noise (V2/Hz).did anyone know how to get drain current noise? really hope someone can help me..


**** NOISE ANALYSIS TEMPERATURE = 27.000 DEG C


******************************************************************************



FREQUENCY = 1.585E-01 HZ




**** MOSFET SQUARED NOISE VOLTAGES (SQ V/HZ)




M_M1

RD 8.615E-29

RS 1.923E-23

RG 1.636E-19

RB 0.000E+00

ID 9.294E-18

FN 2.385E-10

TOTAL 2.385E-10



**** RESISTOR SQUARED NOISE VOLTAGES (SQ V/HZ)




R_R1

TOTAL 1.650E-17





**** TOTAL OUTPUT NOISE VOLTAGE = 2.385E-10 SQ V/HZ

= 1.544E-05 V/RT HZ

TRANSFER FUNCTION VALUE:

V(Vout)/V_Vgs = 8.429E-01

EQUIVALENT INPUT NOISE AT V_Vgs = 1.832E-05 V/RT

 

[keith1200rs]

I am not sure you can get current noise directly out of Hspice from the simulation, but the post processing may be able to do it.

Ways round it may be:

1. add a current source with zero AC/DC values in series with the point you want to measure and define that as the current source for the noise reference simulation (I have never tried that, so do a simple test first to make sure it works).

2. add a current controlled voltage source in series with the point you want to measure and define it's output as the output node of the noise simulation.

Keith.

 

[dieyae16]

i have tried option 1 since i dont know how to use current control voltage source. i have put ISIN like in image below. is it correct the way i put it?



after simulating it here is the output result.

******************************************************************************



FREQUENCY = 1.000E+00 HZ




**** MOSFET SQUARED NOISE VOLTAGES (SQ V/HZ)




M_M1 M_M2

RD 2.105E-29 6.690E-24

RS 2.932E-22 2.698E-23

RG 2.506E-18 3.245E-20

RB 0.000E+00 0.000E+00

ID 1.798E-17 2.831E-19

FN 9.652E-10 1.250E-11

TOTAL 9.652E-10 1.250E-11



**** RESISTOR SQUARED NOISE VOLTAGES (SQ V/HZ)




R_R1 R_R2

TOTAL 2.323E-18 1.161E-18





**** TOTAL OUTPUT NOISE VOLTAGE = 9.777E-10 SQ V/HZ

= 3.127E-05 V/RT HZ

TRANSFER FUNCTION VALUE:

V(Vout)/V_Vin = 3.299E+00

EQUIVALENT INPUT NOISE AT V_Vin = 9.478E-06 V/RT HZ

how can i know which one denote drain current noise (A²/Hz)? or is there any way to find it?

 

[keith1200rs]

OK, I have done some testing and the first method doesn't work (I did say I had never tried it . The problem is that a zero current source passes no current sot he circuit doesn't work. Also, I don't think you have defined an input current source device for the noise analysis, but it doesn't matter as the method doesn't work.

I think the current controlled voltage source is the way to do it. I have attached a simple schematic which tests it and it seems to give the right answers. The noise will be reported as a voltage due to the CCVS, but the value is correct i.e. 2.88pA/rt(Hz).

I am not sure what you are using to draw the schematic, but if you check the CCVS source the syntax is fairly straightforward.

Keith.

 

[dieyae16]

okey..hehe..i'll try your method first. actually i'm using PSPICE schematic to simulate it..