Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

thermal noise and reason of '4' coeffecient

Status
Not open for further replies.

sadid

Advanced Member level 4
Joined
Oct 24, 2006
Messages
112
Helped
4
Reputation
8
Reaction score
2
Trophy points
1,298
Activity points
2,053
in this relation for thermal noise (or resistor noise or jahnson,...):
N=4RkTRB
I want the reason of that 4 as coeffecient.where does that 4 come from? or why?
consider a V source as the source of noise and a series resistor.(may help)
 

A.Anand Srinivasan

Advanced Member level 5
Joined
Oct 15, 2005
Messages
1,804
Helped
257
Reputation
514
Reaction score
39
Trophy points
1,328
Location
India
Activity points
10,680
Pnoise=(Vnoise)²/2R here the 2 is due to average power concept....

noise here the RMS value is used for Vnoise which leads to 1/(√2)² and hence leading to another 2 in the denominator...

we know that Pnoise=kTΔf .... Vnoise²=4kRTΔf.... here a Vnoise would be denoted by a e with a bar above it to mean that the rms value is being used....
 

    sadid

    points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top