HIGH PRECISION IMPEDANCE SENSING INTEGRATED CIRCUIT AND ITS APPLICATIONS

• Main Authors: DONIDA, Achille, ALLEGRI, Daniele Guido, BARRETTINO, Diego Ruben, MASCIADRI, Marco
• Format: Patent
• Language: English
• Published: 04.10.2018
• Subjects: BASIC ELECTRONIC CIRCUITRY; CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; ELECTRICITY; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; PULSE TECHNIQUE; TESTING

There is a low-power multifrequency impedance analyzer based on a monolithic mixed-signal (analog/digital) microchip that performs all the tasks necessary to perform impedance measurements in the frequency range from 10 kHz to 10 MHz. In contrast to a full analog lock-in approach, this mixed-signal solution combines the lock-in approach with the dual step super-heterodyne demodulation scheme. The circuit ensures a CMRR of 81 dB@10 kHz, which increases to 84 dB@10 MHz. The measured equivalent input noise power spectral density is en=2.57 nV/√Hz at 10 kHz in the worst case, close to the 1/f corner frequency. It decreases to en=1.8 nV/√Hz at 1 MHz and en=1.9 nV/√Hz at 10 MHz. Measurements of a reference RC network performed with the proposed low-cost low-power multifrequency impedance analyzer are compared with a Keysight E4980A Precision LCR Meter showing a maximal relative error of 0.8% over the whole operating frequency range.