Infineon Technologies Ag

Hubert Weinberger

Andreas Wiesbauer

Martin Clara

Christian Fleischhacker

Michael Staber

Thomas Pötscher

Jörg Hauptmann

Dietmar Straeussnigg

Thomas Magesacher

J&ouml;rg Hauptmann

Francesco Labate

Günter Koder

An adjustable filter, particularly for use as an antialiasing filter in digital telecommunications networks, includes adjustable capacitors which determine frequency response for the purpose of accurate alignment with a particular cut-off frequency. The active filter includes, in line with the invention, a control device with a measuring device for ascertaining the actual cut-off frequency of the filter. On the basis of the ascertained actual cut-off frequency of the filter and the information about the nominal cut-off frequency which is to be set, an adjustment parameter for the adjustable capacitor is selected from a memory arrangement. This adjustment parameter is used to adjust the adjustable capacitor such that the desired nominal cut-off frequency is obtained and, at the same time, the alignment is performed to achieve the nominal cut-off frequency with sufficient accuracy.

Method and apparatus for adjusting an active filter

Tone signal detection circuit for a receiving circuit for detecting at least one tone signal of predetermined tone signal frequency (f) which is contained in a received analog input signal, comprising a reference signal generator () for generating an analog converter reference signal which consists of a reference DC (V) and a periodic reference AC (V) having a variable fundamental frequency (f), which is superimposed on the reference DC, an analog/digital converter () for converting the analog input signal into a digital data stream in dependence on the analog converter reference signal (V); and comprising a digital control circuit () which adjusts the variable fundamental frequency (f) of the reference signal (V) generated by the reference signal generator () in accordance with the predetermined tone signal frequencies (f) of the tone signals to be detected and evaluates the digital data stream output by the digital analog/digital converter () for detecting a data pattern corresponding to the tone signal.

Tone signal detection circuit for detecting tone signals

The invention creates a method and a device for digitally transmitting analog signals, in which oversampling is performed in analog/digital and digital/analog converters. In this arrangement, a digital/analog conversion is performed which, in particular, is suitable for VDSL systems. A transmitted digital transmission signal () is supplied to a mixing unit () and in the mixing unit (), a receive noise signal () applied to a receive noise source terminal () is superimposed on the digital transmission signal (). An interpolation filter unit (), in combination with a subsequent noise shaping device (), provides an increase in the frequency bandwidth, resulting in suitable oversampling.

Oversampling in analog/digital and digital/analog converters

Digital/analog converter with programmable gain

A sigma-delta analog-to-digital converter array including two cascaded sigma-delta modulators, the two sigma-delta modulators being multi-bit sigma-delta modulators. The sigma-delta analog-to-digital converter array is preferably a third order device and supplies a digital output signal corresponding to a sigma-delta converter with 7-bit quantization. To this end, a second order sigma-delta modulator with 3-bit quantization and a first order sigma-delta modulator with 5-bit quantization may be used.

Sigma-delta analog-to-digital converter array

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Soboth, Austria

Hubert Weinberger