Noise Figure and Noise Voltage

[Eddie W. Shore]

Noise Figure

Given system temperature (in Kelvins), this program calculates the noise figure (in Decibels), which describes the noise performance of an amplifier. The noise figure is described as the difference between the noise output of an actual receiver to an ideal, noiseless receiver. A noiseless receiver is said to have a resistor operating at room temperature, 290 K (about 16.85°C or 62.33°F). The lower the noise figure, the better.

Formula:

F = 10 * log(T/290 + 1)

where:

F = noise figure (dB)
T = system temperature (K)

Code:


HP Prime Program Function:  NOISEDB

EXPORT NOISEDB(T)
BEGIN
// Noise Figure in dB
// Input: T: Temperature (K)
// 2019-01-04 EWS
10*LOG(T/290+1);
END;

Noise Voltage

Given the noise bandwidth (in Hertz) and the resistance (in Ω), calculate the open-circuit voltage (in RMS volts).

Formula:

e_n = √(1.6*10^-20 * B * R)

where:

e_n = open circuit voltage noise (RMS volts)
B = bandwidth (Hz)
R = resistance (Ω)

HP Prime Program Function: NOISEVOLT

Code:


EXPORT NOISEVOLT(b,r)
BEGIN
// Noise Voltage in V
// Input: B=bandwidth (Hz)
// Input: R=resistor (Ω)
// input numbers only
√(1.6ᴇ−20*b*r);
END;

Source:

Ball, John A. Algorithms For RPN Calculators John Wiley & Sons: New York 1978. ISBN 0-471-03070-8

Blog link: https://edspi31415.blogspot.com/2019/01/...e-and.html