Interfacing Resonant Sensors using Ringdown Measurement
- A 30-ppm <80 nJ Ring-Down-Based Readout Circuit for Resonant Sensors
H. Jiang; Z. Y. Chang; M. A. P. Pertijs;
IEEE Journal of Solid-State Circuits,
Volume 51, Issue 1, pp. 187‒195, January 2016. DOI: 10.1109/JSSC.2015.2470552
Abstract: ...This paper presents an energy-efficient readout circuit for micro-machined resonant sensors. It operates by briefly exciting the sensor at a frequency close to its resonance frequency, after which resonance frequency and quality factor are determined from a single ring-down transient. The circuit employs an inverter-based trans-impedance amplifier to sense the ring-down current, with a programmable feedback network to enable the readout of different resonant sensors. An inverter-based comparator with dynamically-adjusted threshold levels tracks the ring-down envelope to measure quality factor, and detects zero crossings to measure resonance frequency. The excitation frequency is dynamically adjusted to accommodate large resonance frequency shifts. Experimental results obtained with a prototype fabricated in 0.35 μm standard CMOS technology and three different SiN resonators are in good agreement with conventional impedance analysis. The prototype achieves a frequency resolution better than 30 ppm while consuming less than 80 nJ/meas from a 1.8 V supply, which is 7.8x less than the state-of-the-art.
- A 30ppm <80nJ ring-down-based readout circuit for resonant sensors
H. Jiang; Z. Y. Chang; M. Pertijs;
In Dig. Techn. Papers IEEE International Solid-State Circuits Conference (ISSCC),
IEEE, pp. 482‒483, February 2015. DOI: 10.1109/ISSCC.2015.7063136
Abstract: ...A readout circuit for MEMS resonant sensors, realized in 0.35μm CMOS, employs a dynamically-switching level-crossing detector to determine resonance frequency and quality factor from a single ring-down transient. Results obtained with three different resonators are in good agreement conventional impedance analysis. The circuit achieves a frequency resolution better than 30 ppm while consuming less than 80 nJ/meas from a 1.8V supply, 7.8x less than the state-of-the-art.
- An energy-efficient reconfigurable readout circuit for resonant sensors based on ring-down measurement
Y. Yan; Z. Zeng; C. Chen; H. Jiang; Z. Y. Chang; D. M. Karabacak; M. A. P. Pertijs;
In Proc. IEEE Sensors Conference,
IEEE, pp. 221‒224, October 2014. DOI: 10.1109/icsens.2014.6984973
- An energy-efficient readout circuit for resonant sensors based on ring-down measurement
Z. Zeng; M. A. P. Pertijs; D. M. Karabacak;
Review of Scientific Instruments,
Volume 84, Issue 2, pp. 025005, February 2013. DOI: 10.1063/1.4792396
Abstract: ...This paper presents an energy-efficient readout circuit for resonant sensors that operates based on a transient measurement method. The resonant sensor is driven at a frequency close to its resonance frequency by an excitation source that can be intermittently disconnected, causing the sensor to oscillate at its resonance frequency with exponentially decaying amplitude. By counting the zero crossings of this ring-down response, the interface circuit can detect the resonance frequency. In contrast with oscillator-based readout, the presented readout circuit is readily able to detect quality factor (Q) of the resonator from the envelope of the ring-down response, and can be used even in the presence of large parasitic capacitors. A prototype of the readout circuit has been integrated in 0.35 μm CMOS technology, and consumes only 36 μA from a 3.3 V supply during a measurement time of 2 ms. The resonance frequency and quality factor of a micro-machined SiN resonator obtained using this prototype are in good agreement with results obtained using impedance analysis. Furthermore, a clear transient response is observed to ethanol flow using the presented readout, demonstrating the use of this technique in sensing applications.
- An energy-efficient interface for resonant sensors based on ring-down measurement
M. A. P. Pertijs; Z. Zeng; D. M. Karabacak; M. Crego-Calama; S. H. Brongersma;
In Proc. IEEE International Symposium on Circuits and Systems (ISCAS),
IEEE, pp. 990‒993, May 2012. (invited paper). DOI: 10.1109/iscas.2012.6272213