Weakly-Coupled Resonators in Capacitive Readout Circuits

Abstract

Low energy consumption and wide operating temperature range of capacitors made them common in sensor designs, e.g., MEMS accelerometers, and hence increased the popularity of capacitive readout circuits. Their main challenges, in either discrete or integrated implementations, are sensitivity, noise, energy consumption, and parasitic components at the analog front end. Compared to conventional "frequency-shift monitoring" which is one of the most accurate and common methods for capacitance measurements, weakly-coupled resonators (well-known in mechanical systems) can offer up to three orders of magnitude increase in sensitivity. Therefore, this concept has been recently applied to the design of micromechanical sensors, e.g., for sensitive mass sensing. This paper applies, for the first time in the electrical domain, the concept of monitoring the eigenstates variations in weakly-coupled resonators as a generic readout circuit technique for measuring very small capacitance changes. The outstanding sensitivity of this method is verified analytically and demonstrated using both extensive circuit simulations and experimental measurements.

Theory on asymmetrical coupled‐parallel‐line transmission and reflection zeros

“…For example, the coupled line can be employed for the bus link used to ensure the equipartitioned energy . The design and implementation of high performance microwave coupled line filters constitute one of the most attractive breakthroughs for the electronic design and research engineers. Basically, the employed topologies are based on the stub‐embedded resonators with the synthesis of the transmission zeros (TZs) and reflection zeros (RZs).…”

“…In complementary to the digital system signal integrity analyses, the coupled line networks are regularly used to design microwave planar circuits thanks to its benefits in term of the compactness [29][30][31][32][33]. For example, the coupled line can be employed for the bus link used to ensure the…”

“…The basic filter block is built with stepped impedance resonators. To meet the multistandard demand for wireless communication system, more complex synthesis approach for a multiband low temperature co-fired ceramics bandpass filter was also implemented [32].Despite this diversity of coupled line applications, further investigation is still needed for the implementation of optimum termination networks. A tentative method was suggested on the basis of the coupling mode and matrix approaches [33,34].…”

Simulation of Mass Sensor Based on Luminescence of Micro/Nano Electromechanical Resonator

“…There have been two dominant readout methods, namely electronic and optical readout. For the electronic readout, requency measurement circuits are needed to extract the frequency change of the resonator [5]. For the optical readout mechanism, quite often a precisely aligned optical setup is required, i.e.…”

Analysis of Sensitivity and Power Consumption of Chopping Techniques for Integrated Capacitive Sensor Interface Circuits

“…Capacitive sensing has the benefits of a low temperature coefficient, low power dissipation and low noise. Additionally, the devices can be easily integrated with CMOS circuits and they are compatible with VLSI technology scaling [6][7][8].…”