Stmicroelectronics Gmbh

Stmicroelectronics S.r.l.

J&uuml;rgen L&uuml;bbe

Peter Kirchlechner

J&ouml;rg Schambacher

Johann Henkel

A method of signal compression of a signal to reduce the large dynamic range, for example, of the output signal of a CD player in such a way that soft passages of a piece of music are reproduced in somewhat louder manner and very loud passages of a piece of music some are reproduced in somewhat less loud manner. The signal compression circuit used therefor can be integrated completely. The audio signal is fed over a volume control, which can be adjusted by the user, and to this end, a digital setting signal in accordance with the adjustment made on the user side, is supplied via a bus line. When the audio signal is strongly increasing, a tracking signal is formed of said signal, with the amplitude thereof being dependent on the medium amplitude of the audio signal. A window comparator compares the tracking signal with a reference value, as a consequence of which the contents of the up/down counter are reduced. This reduced value is added via an adder to the digital setting signal for the volume control. In the case of strong audio signals, a relatively small value corresponding to the count of counter is added to the digital setting signal. In the case of weak signals, a relatively high value is added.

Signal compressor for audio apparatus

An SC filter with intrinsic anti-alias function for adjustably decreasing or increasing the amplitude of audio signals in a predetermined frequency range. The SC filter includes a filter module having an RC network with at least one frequency-response-determining RC member whose resistor component R is realized in SC technology. The SC filter also includes a setting means connected to the filter module such that its setting determines the frequency response of the SC filter. The setting means also renders possible a neutral setting in which the effective audio signal path of the SC filter circumvents the filter module so that no decrease or increase of the amplitude of individual frequency portions takes place. An anti-alias low pass filter unit is connected into the audio signal path when the setting means is not set to the neutral setting and the anti-alias low pass filter unit is not located in the audio signal path when the setting means is set to the neutral setting. Furthermore, an audio singal processor may include such a filter.

Switched capacitor filter with a neutral bypass setting

In an integrated circuit comprising a so-called &ldquo;switched&rdquo; capacitor, the latter is switched by a parallel circuit of two complementary switching transistors having mutually complementary switching pulse trains. Due to parasitic effects during this switching operation, disturbing offset voltages arise at the switched capacitor. In order to avoid such offset voltages, the edges of the one switching pulse train are shifted in time with respect to the corresponding edges of the complementary switching pulse train. To this end, a switching pulse generator contains a delay member fed with a control signal which is formed by means of a constant reference voltage using a dummy or simulation of that circuit that contains the switched capacitor.

Growing community of inventors

Jacobneuharting, Germany

Jürgen Lübbe

Growing community of inventors

Jacobneuharting, Germany

J&uuml;rgen L&uuml;bbe

Jürgen Lübbe