Noise reduction apparatus for low level analog signals

摘要

Pairs of signal input leads with a low level signal imposed across them usually have noise induced by stray coupling capacitance which is typically unequal. This results in an unfavorable signal to noise ratio. Adding enough capacitance to the lead having the least capacitance, thereby equalizing the coupling capacitances to the noise services thereof, tends to reduces the noise effect considerably. This is accomplished by changing the relative sizes of the anode and/or cathode of a corresponding sensor device. The noise effect is further reduced by a negative feedback process which comprises extracting the induced noise component from the leads, inverting the noise component, and coupling the inverted noise component back to the input leads.