0.5 V and 0.43 pJ/bit capacitive sensor interface for passive wireless sensor systems

Autores: Beriain Rodríguez, Andoni (Autor de correspondencia); Gutiérrez García, Íñigo; Solar Ruiz, Héctor; Berenguer Pérez, Roque José
Título de la revista: SENSORS
ISSN: 1424-8220
Volumen: 15
Número: 9
Páginas: 21554 - 21566
Fecha de publicación: 2015
Lugar: WOS
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 mm(2) 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.