A CMOS smart temperature and humidity sensor with combined readout.
Sensors (Basel)
; 14(9): 17192-211, 2014 Sep 16.
Article
en En
| MEDLINE
| ID: mdl-25230305
ABSTRACT
A fully-integrated complementary metal-oxide semiconductor (CMOS) sensor for combined temperature and humidity measurements is presented. The main purpose of the device is to monitor the hermeticity of micro-packages for implanted integrated circuits and to ensure their safe operation by monitoring the operating temperature and humidity on-chip. The smart sensor has two modes of operation, in which either the temperature or humidity is converted into a digital code representing a frequency ratio between two oscillators. This ratio is determined by the ratios of the timing capacitances and bias currents in both oscillators. The reference oscillator is biased by a current whose temperature dependency is complementary to the proportional to absolute temperature (PTAT) current. For the temperature measurement, this results in an exceptional normalized sensitivity of about 0.77%/°C at the accepted expense of reduced linearity. The humidity sensor is a capacitor, whose value varies linearly with relative humidity (RH) with a normalized sensitivity of 0.055%/% RH. For comparison, two versions of the humidity sensor with an area of either 0.2 mm2 or 1.2 mm2 were fabricated in a commercial 0.18 µm CMOS process. The on-chip readout electronics operate from a 5 V power supply and consume a current of approximately 85 µA.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Semiconductores
/
Transductores
/
Procesamiento de Señales Asistido por Computador
/
Agua
/
Termografía
/
Embalaje de Productos
/
Humedad
Idioma:
En
Revista:
Sensors (Basel)
Año:
2014
Tipo del documento:
Article
País de afiliación:
Reino Unido