Abstract: The invention relates to a Polyphase-Notchfilter for filtering input signals comprising known bandpass filters, which comprise voltage-controlled current sources. To provide an integrated circuit that has notch filter functionality with reduced circuit erogation, that allows high suppression with little matching effort and reduced power consumption it is proposed that at least two second voltage-controlled current sources are provided, that said at least four input means are coupled to said at least two second voltage-controlled current sources, and that said at least four output means are coupled to said at least two second voltage-controlled current sources, and that said at least one second voltage-controlled current sources are coupled antiparallel to bandpass filter.

Abstract: The invention relates to a Polyphase-Notchfilter for filtering input signals comprising known bandpass filters, which comprise voltage-controlled current sources. To provide an integrated circuit that has notch filter functionality with reduced circuit erogation, that allows high suppression with little matching effort and reduced power consumption it is proposed that at least two second voltage-controlled current sources are provided, that said at least four input means are coupled to said at least two second voltage-controlled current sources, and that said at least four output means are coupled to said at least two second voltage-controlled current sources, and that said at least one second voltage-controlled current sources are coupled antiparallel to bandpass filter.

Abstract: A Pierce oscillator has been modified to replace the large capacitor with an amplifier element in order to make it more compact. A first amplifier element has a control terminal and a main current path extending between first and second output terminals. A network feeds back the signal at the first output terminal of the first amplifier to the control terminal of the first amplifier element and includes a series-arranged piezoelectric oscillation element. The oscillator also includes a reactive circuit element such as a resonant LC circuit or inductor (herein called an output dipole) coupled to the first output terminal of the first amplifier element and a DC current defining element coupled to the second output terminal of the first amplifier element.