Patent ID: 8390304
Filing Date: 2013-03-05
Classification: G01N,G01R

Abstract:
1. A conductivity measuring apparatus, comprising: a. a variable frequency, high output impedance, current source; b. a sample cell having both resistive and capacitive characteristics electrically connected to the current source; c. a low-loss, low-noise inductance connected to the current source and in parallel with the sample cell, such that the sample cell and inductance effectively form a parallel RLC circuit; d. a high input impedance buffer amplifier connected to the output of the parallel RLC circuit; e. a phase sensitive detector connected to the output of the high input impedance buffer amplifier; f. a background conductivity offset circuit; g. a differencing amplifier with a first input connected to the output of the phase sensitive detector and a second input connected to the output of the background conductivity offset circuit; and h. a high gain output amplifier connected to the output of the differencing amplifier.