DEVELOPMENTS IN INTEGRATED SMART SENSORS

An integrated smart sensor (ISS) can be defined as a chip that contain s the functions of sensing, signal conditioning, AD conversion and a b us output. It may also have on-chip calibration and self-test. This pa per concentrates on the standardization of the output interface using on-chip AD conversion, calibration and bus output. First, it is shown how indirect AD-conversion techniques yield simple circuits which can easily coexist with the sensor on one chip. Sigma-delta conversion is a good example. Second, calibration methods are described for analog a nd digital sensor output signals. Finally, the use of two simple busse s is described, the (IC)-C-2 bus and the IS2 bus. The required bus int erfaces are relatively simple and can be integrated with sensors in bi polar as well as in CMOS processes.