Design methodology of an audio sensor system using switched-current cells

This paper describes the design and simulation of a current-mode filter that is to be part of an application specific integrated circuit (ASIC) for signal conditioning the input from an audio sensor. Such filters may be used in electronic systems where sensors are used to measure physical parameters in order to provide information to the human user. The filter design described in this paper is based on switched-current (SI) design techniques (in particular a biquadratic filter is implemented for this design). With the SI design technique, variations in current values may be achieved with relatively small variations in nodal voltage. In addition, the power supply requirements and fabrication cost will be two considerations for the final choice of implementation method. In this study, current-mode design techniques are used for its suitability in low voltage operation and the ability to create analogue signal conditioning circuitry using a standard digital CMOS fabrication process. This ability to utilize a digital fabrication process may result in a lower cost solution than using an analogue fabrication process.