1.5 V Sub-mW CMOS Interface Circuit for Capacitive Sensor Applications in Ubiquitous Sensor Networks

  • Lee, Sung-Sik (Convergence Components & Materials Research Laboratory, ETRI) ;
  • Lee, Ah-Ra (Convergence Components & Materials Research Laboratory, ETRI) ;
  • Je, Chang-Han (Convergence Components & Materials Research Laboratory, ETRI) ;
  • Lee, Myung-Lae (Convergence Components & Materials Research Laboratory, ETRI) ;
  • Hwang, Gunn (Convergence Components & Materials Research Laboratory, ETRI) ;
  • Choi, Chang-Auck (Convergence Components & Materials Research Laboratory, ETRI)
  • Received : 2008.02.12
  • Accepted : 2008.08.18
  • Published : 2008.10.31

Abstract

In this paper, a low-power CMOS interface circuit is designed and demonstrated for capacitive sensor applications, which is implemented using a standard 0.35-${\mu}m$ CMOS logic technology. To achieve low-power performance, the low-voltage capacitance-to-pulse-width converter based on a self-reset operation at a supply voltage of 1.5 V is designed and incorporated into a new interface circuit. Moreover, the external pulse signal for the reset operation is made unnecessary by the employment of the self-reset operation. At a low supply voltage of 1.5 V, the new circuit requires a total power consumption of 0.47 mW with ultra-low power dissipation of 157 ${\mu}W$ of the interface-circuit core. These results demonstrate that the new interface circuit with self-reset operation successfully reduces power consumption. In addition, a prototype wireless sensor-module with the proposed circuit is successfully implemented for practical applications. Consequently, the new CMOS interface circuit can be used for the sensor applications in ubiquitous sensor networks, where low-power performance is essential.

Acknowledgement

Supported by : IITA