Abstract: A CMOS circuit (10), which is integrated in a semiconductor substrate, comprises a principal circuit part (12), which includes the major part of the circuit components in a well isolated from the substrate by a substrate diode. The CMOS circuit furthermore comprises a power output stage (16) driving an inductive load (26, 28). A sensor (18) is connected with one output (22, 24) of the power output stage (16) and on detection of a voltage biasing the substrate diode (30, 32) in the conducting direction produces a switching signal at the output. On occurrence of the switching signal produced by the sensor (18) a controllable switch (20) disconnects the supply voltage from the principal circuit part (12). In its own separate well (46) a status memory (14) is formed on the substrate adjacent to the principal circuit part (12), such status memory (14) comprising memory elements for storage of status data of the principal circuit part (12) on disconnection of the supply voltage.

Abstract: An interrogation unit which has a control circuit and an RF oscillator is described. The interrogation unit further has a transmitter which receives the output of the RF oscillator and transmits at least one RF interrogation pulse of a first frequency for interrogating the responder unit, causing the responder unit to return read data in the form of a RF response. Also in the interrogation unit is a switch for disabling the output of said transmitter and enabling reception of the RF response upon termination of the RF interrogation signal. The interrogation unit still further has a receiver for receiving the RF response upon termination of the RF interrogation pulse and an interrogation unit demodulator for demodulation of the read data from said RF response.

Abstract: A responder unit for communicating with an interrogator unit which sends an RF interrogation pulse thereto is described. The responder unit includes an energy accumulator which stores the energy contained in the RF interrogation pulse to be used to power the responder unit in the absence of any RF interrogation signal. The responder unit also has a memory for storing read data and a RF threshold detector for detecting termination of the RF interrogation pulse. A RF carrier wave generator under control of the RF threshold detector is operable to activate upon detection of the termination of the RF interrogation pulse. A modulator is provided in the responder unit to modulate the RF carrier with the read data from the memory.

Abstract: A transponder arrangement is described comprising an interrogation unit (10) which sends an RF interrogation pulse to at least one responder unit (12). The responder unit (12) then transmits back data stored therein in the form of a modulated RF carrier to the interrogation unit (10). In the responder unit (12) is an energy accumulator (136) which stores the energy contained in the RF interrogation pulse. The responder unit (12) further contains means (142, 148) which in dependence upon the termination of the reception of the RF interrogation pulse and the presence of a predetermined energy amount in the energy accumulator (126) initiate the excitation of an RF carrier wave generator (130, 132, 134) operating with the frequency contained in the RF interrogation pulse.

Abstract: The invention relates to a field-effect transistor (1;20) with insulated gate electrode (9;30) which comprises in a semiconductor body (5) a drain diffusion zone (2) connected to a drain electrode (6;32) and a source diffusion zone (3) which is disposed spaced from the drain diffusion zone (2) for forming a channel zone (4) and which is connected to a source electrode (7). The gate electrode (9;32) of said field-effect transistor is disposed on a gate insulating layer (8) over the channel zone (4). For protecting the transistor against high voltages produced by electrostatic charging the drain diffusion zone (2) of the transistor and/or the source diffusion zone (3) between the respective associated electrode (6,7;32) and the channel zone (4) is divided into a plurality of parallel strips (10,11). Integrated circuits are also protected against destruction by high voltages if the insulated gate field-effect transistors connected to their output terminals are constructed in the manner outlined above.