A Self-Sustained CMOS Microwave Chemical Sensor Using a Frequency Synthesizer

作者：Helmy Ahmed A^*; Jeon Hyung Joon; Lo Yung Chung; Larsson Andreas J; Kulkarni Raghavendra; Kim Jusung; Silva Martinez Jose; Entesari Kamran

来源：IEEE Journal of Solid-State Circuits, 2012, 47(10): 2467-2483.

DOI：10.1109/JSSC.2012.2203458

• Dielectric constant
• frequency synthesizer
• microwave sensor
• oscillator

In this paper, a CMOS on-chip sensor is presented to detect dielectric constant of organic chemicals. The dielectric constant of these chemicals is measured using the oscillation frequency shift of an LC voltage-controlled oscillator (VCO) upon the change of the tank capacitance when exposed to the liquid. To make the system self-sustained, the VCO is embedded inside a frequency synthesizer to convert the frequency shift into voltage that can be digitized using an on-chip analog-to-digital converter. The dielectric constant is then estimated using a detection procedure including the calibration of the sensor. The dielectric constants of different organic liquids have been detected in the frequency range of 7-9 GHz with an accuracy of 3.7% compared with theoretical values for sample volumes of 10-20 mu L. The sensor is also applicable for binary mixture detection and estimation of the fractional volume of the constituting materials with an accuracy of 1%-2%.

• 出版日期2012-10