A 9 MHz–2.4 GHz Fully Integrated Transceiver IC for a Microfluidic-CMOS Platform Dedicated to Miniaturized Dielectric Spectroscopy

This paper presents a fully integrated transceiver IC as part of a self-sustained, microfluidic-CMOS platform for miniaturized dielectric spectroscopy (DS) from MHz to GHz. Fabricated in AMS $0.35~\mu{\rm m}$ 2P/4M RF CMOS, the transmitter (TX) part of the IC generates a single-tone sinusoidal signal with frequency tunability in the range of $\sim 9~{\rm MHz}{mathchar"702D}2.4~{\rm GHz}$ to excite a three-dimensional (3D), parallel-plate, capacitive sensor with a floating electrode and $9~\mu{\rm L}$ microfluidic channel for sample delivery. With a material-under-test (MUT) loaded into the sensor, the receiver (RX) part of the IC employs broadband frequency response analysis (bFRA) methodology to measure the amplitude and phase of the RF excitation signal after transmission through the sensor. A one-time, 6-point sensor calibration algorithm then extracts both the real and imaginary parts of the MUT complex permittivity, $\epsilon_{r}$ , from IC measurements of the sensor transmission characteristics in the voltage domain. The “sensor $+$ IC” is fully capable of differentiating among de-ionized (DI) water, phosphate-buffered saline (PBS), and alcoholic beverages in tests conducted at four excitation frequencies of $\sim 50~{\rm MHz}$ , 500 MHz, 1.5 GHz, and 2.4 GHz generated by the TX. Moreover, permittivity readings of PBS by the sensor interfaced with the IC at six excitation frequencies in the range of $\sim 50~{\rm MHz}{mathchar"702D}2.4~{\rm GHz}$ are in excellent agreement (- ms error of 1.7% (real) and 7.2% (imaginary)) with those from bulk-solution reference measurements by commercial benchtop equipment. The total power consumption of the IC is $< 100~{\rm mW}$ with 1.5 V (analog) and 3.3 V (digital) supplies.