A multifunctional multichip system can operate in a passive mode by using at least one antenna to receive electromagnetic energy and using that energy to perform system functions. The system includes a sensor, an impedance matching circuit and an RFID module. The sensor produces a sensor signal containing a measurement. The RFID can produce an identification signal containing identification information. Alternatively, the RFID chip can be used in an addressing mode wherein the system only produces a signal in response to an addressing signal containing addressing information. The addressing signal is received from the electromagnetic field. In either mode, the sensor signal is coupled from the antenna into the electromagnetic field from which a receiver can obtain it. The signal can contain the identification information as well as the measurement. A matching network minimizes the effects of impedance mismatches between the system elements.