Electronic device comprising an operating mode switching unit

摘要

An electronic appliance comprising an electrical circuit and an operating mode switching unit which can be awakened out of a sleep state into a working state in which the current consumption of the circuit is greater in than in the sleep state. To receive a radio signal, the appliance has a receiver comprising a UHF carrier that is amplitude-modulated by a modulation signal. The receiver comprises a UHF antenna connected to a passive filter stage to an input of a passive rectifier circuit. An output of the rectifier circuit is connected to a detector for the modulation signal. To wake the electrical circuit from the sleep state, the operating mode switching unit has a control connection to the detector. The appliance has a low current draw in the sleep state by matching the output impedance of the rectifier circuit to the input impedance of the detector.

主权项

1. An electronic appliance (1) having an electrical circuit and an operating mode switching device (18) which is associated with the latter and which can be used to wake the electrical circuit from a quiescent state into an operating state in which the current draw of the electrical circuit is greater than in the quiescent state, having a receiver for receiving a radio signal which has a UHF carrier which has been subjected to amplitude modulation with a modulation signal, wherein the receiver has a UHF antenna (6) which is connected to an input of a passive rectifier circuit (8) via a passive filter stage (7), wherein an output of the passive rectifier circuit (8) is connected to a detection device (16) for the modulation signal, and wherein the operating mode switching device (18) has a control connection to the detection device (16) for the purpose of waking the electrical circuit which is in the quiescent state, the improvement which comprises:
means for matching the output impedance of the rectifier circuit (8) to the input impedance of the detection device (16), wherein the means for matching the output impedance of the rectifier circuit (8) to the input impedance of the detection device (16) includes a passive filter (9) operatively arranged between the output of the passive rectifier circuit (8) and the input of the detection device (16) for passing the modulation signal, and the passive filter stage (7) and/or the passive filter (9) has/have an LC resonant circuit including a quartz oscillator (12) and/or a microacoustic resonator.