Application of logarithmic amplifier in detection of weak optical signal
Changqing Li · Electronic Design Engineering · 2010
In order to extract the signal submerged in the noise in detection circuit,the high-precision amplifiers,especially logarithmic amplifiers,were used to increase the capacity of filtering out the noise,one of the designs was a photoelectric detection circuit using an integrated logarithmic amplifier LOG100 as preamplifier.According to such a circuit,the way of selecting the parameters of the electronic components was raised in designing the low-noise weak-optical detection circuit,and the outputs of LOG100 were detected.Actual measure results show that when the input optical signal power is above 1nW,LOG100 performs a good noise filtering.But when the input optical power is less than 1nW,the noise in output signal is markedly enhanced.Such phenomenon may result in the A/D conversion giving error outputs,and make against to follow-up data processing.