Description

Sensors (detectors/transducers) covers a wide category of devices used to monitor, measure, test, analyze data as generated due to changes in a measured norm (usually concentration for chemical sensors). A scientific discipline that develops and applies methods, instruments and strategies to obtain information on the composition and nature of matter in space and time in this system implemented in CMOS technology to reduce power consumption, number of wires, and active area per channel. The presented integrated circuit also addresses the potential-frequency-locking problem between channels by allowing the open-loop gain to be adjustable off-chip. The latest generations of CMOS imaging technology have diminished the trade-off between resolution and speed by using very high data throughput, made possible by very fast, high bandwidth analog to digital converters. The speed of these devices has challenged the boundaries of available data transmission standards such as Camera Link and has been the primary driving force behind the new high bandwidth Camera Link HS standard. Capacitive micro machined ultrasonic transducers ~CMUTs!, introduced about a decade ago, have been shown to be a good alternative to conventional piezoelectric transducers in various aspects, such as sensitivity, transduction efficiency, and bandwidth. In this paper, we discuss the principles of capacitive transducer operation that underlie these aspects. Many of the key features of capacitive ultrasonic transducers are enabled with micromachining technology. Micromachining allows us to miniaturize device dimensions and produce capacitive transducers that perform comparably to their piezoelectric counterparts.