Abstract: The circuit comprises an amplitude limiter made up with the use of two CMOS transistors and a circuit connected to the output of the amplitude limiter for filtering the signal and changing its level. The filtering and level-changing circuit is arranged, in particular, to achieve band-pass filtering in order to prevent aliasing effects which might arise during the sampling of the signal by subsequent switched-capacitance processing circuits, and to attenuate low-frequency components of the signal.

Abstract: The device includes two channels for detecting and processing the signal provided by an accelerometric sensor, operating in two frequency bands in which peaks indicative of pinking (knocking) may occur. In each combustion phase, a third channel, also connected to the sensor, provides a signal representative of the noise component of the signal from the sensor, in a frequency band in which the peaks do not occur. The signals provided by the first and second channels are integrated and then compared with a reference signal generated in dependence on the noise component detected cylinder by cylinder. The device thus enables pinking to be detected cylinder by cylinder.

Abstract: A switched-capacitor circuit is described, which performs the functions of a full-wave rectifier and of an integrator and has a single operational amplifier and a comparator. The circuit is insensitive to the stray capacitances and offsets of the comparator and the operational amplifier. In particular, the input signal is sampled during only one phase of the clock which pilots the operation of the switched-capacitance network.

Abstract: The signal provided by an accelerometric sensor (S) connected to the engine is monitored in two frequency bands (f1, f2) in which peaks indicative of the presence of pinking (knocking) may appear. The intensity of the signal detected in the second band (f2) is compared (3) with the intensity of the signal detected in the first band (f1). The comparison (20) of the detection-signal component (F1 and/or F2) with the noise component (F3), in view of the emission of the pinking signal (21), is carried out in different ways (8, 13, 14) according to the relative ratios between the above intensities.