US Patent 7501968 Integrated multi-mode sensor

An integrated multi-mode sensor system is described that integrates into a single housing a sensor, signal conditioning circuitry, calibration memory, and interface circuitry that is compatible with both analog and digital end-use circuits. The sensor includes a housing, a sensor circuit, memory, and an interface circuit. The sensor circuit is disposed within the sensor housing, is operable, upon being energized, to supply an output signal that varies with at least one physical parameter to which the sensor circuit is exposed. The interface circuitry disposed within the sensor housing is adapted to receive a mode select signal and the sensor signal. The output circuit is selectively configurable, in response to the mode select signal, to implement one of a plurality of signal processing modes, including analog voltage output, asynchronous pulse density modulation (APDM) and synchronous pulse density modulation (SPDM) of various moduli, and an APDM or SPDM mode using a selectable I2C or SPI interface protocol.