Abstract: An apparatus includes a biquad filter having first and second lossy integrators and multiple input networks. Each lossy integrator includes an amplifier, and each input network is coupled to an input of the amplifier in one of the lossy integrators. Each input network includes multiple resistors and a capacitor arranged in a T-structure. In a single-ended configuration, each input network includes a grounded capacitor. In a fully-differential configuration, each input network includes one of: a grounded capacitor and a floating capacitor coupled to another input network. The amplifiers and resistors could form a portion of an integrated circuit chip, which also includes multiple input/output pins. A single grounded capacitor could be coupled to a single input/output pin of the integrated circuit chip for an input network. A single floating capacitor could be coupled to two input/output pins of the integrated circuit chip for a pair of input networks.

Abstract: A method of detection of a distance variation with respect to an axis of at least one point of an object rotating around this axis by a terminal at a fixed position with respect to the axis and capable of emitting a radiofrequency field for at least one resonant circuit attached to the object. The method includes the steps of measuring and recording, on the terminal side, a maximum value of a quantity representative of the coupling between an oscillating circuit of the terminal and the at least one resonant circuit; and detecting a variation of this periodic maximum.