Ultra Low Power Capacitive Sensor Interfaces

The increasing performance of smart microsystems merging sensors, signal processing and wireless communication promises to have a pervasive impact during the coming decade. These autonomous microsystems nd applications in sport evaluation, health care, environmental monitoring and automotive s- tems. They gather data from the physical world, convert them to electrical form, compensate for interfering variables or non-linearities, and either act - rectly on them or transfer it to other systems. Most often, these sensor systems are developed for a speci c application. This approach leads to a high rec- rent design cost. A generic front-end architecture, where only the sensors and the microcontroller software are customized to the selected application, would reduce the costs signi cantly. This work presents a new generic architecture for autonomous sensor nodes. The modular design methodology provides a exible way to build a complete sensor interface out of con gurable blocks. The settings of these blocks can be optimized according to the varying needs of the application. Furthermore, the system can easily be expanded with new building blocks. The modular system is illustrated in a Generic Sensor Interface Chip (GSIC) for capa- tive sensors. Many con guration settings adapt the interface to a broad range of applications. The GSIC is optimized for ultra low power consumption. It achieves an ON-state current consumption of 40?A.

An increasing number of medical diagnostics, comfort, entertainment, and sports applications are making use of capacitive sensor systems in and around the body. These sensor systems should work as small distributed units that can collect data over a long period of time. So, ultra low power electronics are a major challenge in these applications.

Ultra Low Power Capacitive Sensor Interfaces describes the design and theory of ultra low power capacitive sensor interfaces. The book’s major asset is the realization of a very low power generic sensor interface chip, that is adaptable to a broad range of capacitive sensors.

The book starts with an overview on the most important design aspects for autonomous sensor systems. The different building blocks are discussed and the modular architecture for the generic sensor interface chip is presented. Furthermore, the design of the analog components, such as capacitance-to-voltage converters, switched capacitor amplifier, Sigma Delta modulator, oscillators and reference circuits, is described in more detail. Finally, the generic sensor interface chip is applied in several state-of-the-art pressure sensor and accelerometer applications.

Ultra Low Power Capacitive Sensor Interfaces is essential reading for anybody with an academic or professional interest in semiconductor design.