Noise performance analysis of Op-Amps in use with passive inductive transducers and inductive sensors

Abstract

Some medical and industrial applications use inductive source sensors. In many cases these sensors produce low voltages even lower than 0,1mV. On the other hand these sensors have significant inductance (more than 150mH and up to 1H). This paper investigates the signal to noise performance when use contemporary ultra low noise op-amps in the schematic designs without J-FET buffering. There exist very low noise op-amps with voltage noise less than the noise of $50\Omega$ resistor but they are not suitable for inductive sources.