Left Border Content  RF Cafe




Copyright: 1996  2024 Webmaster:
Kirt Blattenberger,
BSEE  KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dialup modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
AirplanesAndRockets.com


SubHeader  RF Cafe

Opamp Noise Figure 
These equations calculate
the noise figure of an opamp using parameters provided by vendors at the operating frequency and gain
configurations. Be sure to note units both for the input parameters and for the equations, or you will end up with
really bad results. I originally got these formulas from an engineering desk reference, but a source accessible by
everyone is "Noise Analysis for
HighSpeed Op Amps," by Texas Instruments (see page 9).
Approximation Formula
V_{NOISE }= Noise voltage density, i.e. nV/sqrt(Hz) I_{NOISE }= Noise current density, i.e.
pA/sqrt(Hz) R_{S} = Source resistance, i.e. 50 Ω
k = Boltzmann's Constant = 1.380 662 x 10^{23} J/K T = Ambient temperature in Kelvin
E_{NI} = Input noise voltage
I_{BN} = Noninverting input noise current
I_{BI} = Inverting noise current
R_{S} = Source resistor
R_{T}
= Termination resistor
R_{F} = Feedback resistor
R_{G} = Gain setting resistor

Footer  RF Cafe


Right Border Content  RF Cafe
