0.5 V and 0.43 pJ/bit Capacitive Sensor Interface for Passive Wireless Sensor Systems.
This paper presents an ultra low-power and low-voltage pulse-width modulation based ratiometric capacitive sensor interface. The interface was designed and fabricated in a standard 90 nm CMOS 1P9M technology. The measurements show an effective resolution of 10 bits using 0.5 V of supply voltage. The active occupied area is only 0.0045 mm2 and the Figure of Merit (FOM), which takes into account the energy required per conversion bit, is 0.43 pJ/bit. Furthermore, the results show low sensitivity to PVT variations due to the proposed ratiometric architecture. In addition, the sensor interface was connected to a commercial pressure transducer and the measurements of the resulting complete pressure sensor show a FOM of 0.226 pJ/bit with an effective linear resolution of 7.64 bits. The results validate the use of the proposed interface as part of a pressure sensor, and its low-power and low-voltage characteristics make it suitable for wireless sensor networks and low power consumer electronics.
CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, Donostia 20018, Spain. aberiain@ceit.es.
Andoni
A
Beriain
CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, Donostia 20018, Spain. ingutierrez@ceit.es.
Iñigo
I
Gutierrez
CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, Donostia 20018, Spain. hsolar@ceit.es.
Hector
H
Solar
CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, Donostia 20018, Spain. rberenguer@ceit.es.
Roc
R
Berenguer
capacitive-sensor interface; low-power sensor interface; period modulation; pressure sensor