noise current การใช้

;Noise-equivalent power : ( NEP ) The minimum input optical power to generate photocurrent, equal to the rms noise current in a 1 hertz bandwidth.
Though the output noise voltage increases proportionally to \ sqrt { R _ { f } }, the transimpedance increases linearly with R _ { f }, resulting in an input-referred noise current
From this measurement a useful parameter that provides quantitative information on the noise of the optical source can be evaluated : it is the relative intensity noise ( RIN ), that is the ratio between the power spectral density of the noise current, I n, measured over a given bandwidth, and the square value of the average photocurrent, I 0
Pre-amplifiers designed for high input impedance may have a slightly higher effective noise voltage at the input ( while providing a low effective noise current ), and so slightly more noisy than an amplifier designed for a specific low-impedance source, but in general a relatively low-impedance source configuration will be more resistant to noise ( particularly mains hum ).