| dc.contributor | MARIA TERESA SANZ PASCUAL | |
| dc.creator | LUIS CARLOS ALVAREZ SIMON | |
| dc.date | 2014-12 | |
| dc.date.accessioned | 2023-07-25T16:21:20Z | |
| dc.date.available | 2023-07-25T16:21:20Z | |
| dc.identifier | http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/316 | |
| dc.identifier.uri | https://repositorioslatinoamericanos.uchile.cl/handle/2250/7805536 | |
| dc.description | The development of portable, low cost, low power and high performance gas
sensing systems based on MOX gas sensors involves advances in three areas: chemical
sensors, data analysis algorithms or information extraction methods and electronic
circuits to interface the sensors with the data processor. Currently, several
data analysis algorithms and operation modes of MOX gas sensors have been
developed and are being tested to improve their poor selectivity and stability of
such sensors. However, to attain a practical high accuracy gas sensing system, it is
also necessary to develop a high accuracy interface circuit. Furthermore, for sensor
network applications, the interface circuit needs to have low power consumption
and low cost.
This thesis proposes circuit topologies to implement CMOS interface circuits for
resistive chemical sensors. Specifically a general topology is proposed for the readout
circuit that not only handles a wide dynamic range of resistance variation but
also allows to implement resistance to period converters robust to supply and
environment temperature variations. Furthermore, a flexible temperature control
system is presented that enables handling heaters with different requirements in
power consumption to achieve the desired operating temperature of the sensor.
The simplicity and flexibility of the proposed topologies can facilitate the interface
circuit implementation to different technology nodes.
The proposed readouts and temperature control circuits were implemented in an
180nm CMOS technology. One the one hand, five Resistance-to-Period Converters
(RTC) based on first order relaxation oscillators were designed. The circuits were
tested with ±10% of variations in supply voltage and a range of environment
temperature from 3 to 95◦C. Experimental results showed that the proposed topology
can get robust RTCs to temperature and supply voltage variations without accuracy
biasing circuits or high-performance sub-circuits, maintaining deviations in
the output signal in the order of ±1% in almost two decades of resistance variations.
On the other hand, a temperature control circuit based on the on/off control
technique was also designed. The functionality of the control circuit was tested
using the commercial AS-MLC gas sensor. Experimental results showed a resolution
of ±4.5◦C in the operating temperature control. | |
| dc.format | application/pdf | |
| dc.language | eng | |
| dc.publisher | Instituto Nacional de Astrofísica, Óptica y Electrónica | |
| dc.relation | citation:Alvarez-Simon L.C. | |
| dc.rights | info:eu-repo/semantics/openAccess | |
| dc.rights | http://creativecommons.org/licenses/by-nc-nd/4.0 | |
| dc.subject | info:eu-repo/classification/Convertidores R-T/R-T converters | |
| dc.subject | info:eu-repo/classification/Circuitos de interfaz/Interface circuits | |
| dc.subject | info:eu-repo/classification/Sensores de gas MOX/MOX gas sensors | |
| dc.subject | info:eu-repo/classification/cti/1 | |
| dc.subject | info:eu-repo/classification/cti/22 | |
| dc.subject | info:eu-repo/classification/cti/2203 | |
| dc.subject | info:eu-repo/classification/cti/2203 | |
| dc.title | CMOS interface circuits for metal-oxide gas sensors | |
| dc.type | info:eu-repo/semantics/doctoralThesis | |
| dc.type | info:eu-repo/semantics/acceptedVersion | |
| dc.audience | students | |
| dc.audience | researchers | |
| dc.audience | generalPublic | |
