Patent ID: 6847215

Claim:
An electronic circuit for detecting a change with respect to a quiescent condition, which circuit includes oscillation means comprising at least a first and a second oscillator circuit, each circuit comprising an oscillator input terminal and an oscillator output terminal on which an oscillation signal is present, the oscillator input of the first oscillator circuit being coupled with the oscillator output of the second oscillator circuit, and the oscillator input of the second oscillator circuit being coupled with the output of the first oscillator circuit, as well as detection means comprising at least a first and a second detection circuit each detection circuit comprising a detection output terminal on which a detection signal is present, the detection means being arranged for detecting a change between the oscillation signals of the at least two oscillator circuits as a result of an external influencing, the detection and oscillator circuits being substantially symmetrical or identical to each other, the first and second detection circuit forming a part of the first and the second oscillator circuit, respectively, each oscillator circuit comprising at least one bipolar transistor, of which the base forms both the oscillator input terminal, the emitter forms the detection output terminal, in the collector path a resonance circuit being included, with the collector forming the oscillator output terminal.