Abstract: Implementations related to echo cancellation are depicted and described herein.

Abstract: at least one self oscillating loop circuit which oscillates with a switching frequency (fs), wherein the self oscillating loop circuit (18, 19, 20) comprises an output driver (19) which is switched with said switching frequency and a loop filter (20) which feeds back an amplified loop signal output by said driver (19) to an input of said self oscillating loop and a trimming circuit (21) for trimming the switching frequency (fs) of said self oscillating loop circuit.

Abstract: The invention relates to a sigma-delta analogue/digital converter for an xDSL multi-standard input stage for converting an xDSL signal into a digital output signal, where the sigma-delta analogue/digital converter (1) has: an analogue loop filter (6) which filters an analogue difference signal between the xDSL signal to be converted and a feedback signal in order to produce a filter output signal; a quantizer which quantizes the filter output signal from the analogue loop filter (6) in order to produce the digital output signal; a first digital/analogue converter (16) which converts the digital output signal into the analogue feedback signal; where the analogue loop filter (6) has at least two resonator filter stages (6a, 6b) which respectively comprise a first integrator (6a-1; 6b-1) and a second integrator (6a-2; 6b-2) connected in series therewith, where the second integrator (6a-2; 6b-2) can be connected to the first integrator (6a-1, 6b-1) by means of a controllable feedback switch (6a-3, 6b-3) in order

Abstract: Implementations related to echo cancellation are depicted and described herein.

Abstract: The invention relates to a sigma-delta analogue/digital converter for an xDSL multi-standard input stage for converting an xDSL signal into a digital output signal, where the sigma-delta analogue/digital converter (1) has: an analogue loop filter (6) which filters an analogue difference signal between the xDSL signal to be converted and a feedback signal in order to produce a filter output signal; a quantizer which quantizes the filter output signal from the analogue loop filter (6) in order to produce the digital output signal; a first digital/analogue converter (16) which converts the digital output signal into the analogue feedback signal; where the analogue loop filter (6) has at least two resonator filter stages (6a, 6b) which respectively comprise a first integrator (6a-1; 6b-1) and a second integrator (6a-2; 6b-2) connected in series therewith, where the second integrator (6a-2; 6b-2) can be connected to the first integrator (6a-1, 6b-1) by means of a controllable feedback switch (6a-3, 6b-3) in order

Abstract: The invention relates to a line terminating device for a subscriber line which transmits and receives broadband signals via a single subscriber line, a broadband signal being composed of a broadband or narrowband audio-frequency data signal and a broadband higher-frequency data signal and the frequency bands of the voice signal and of the data signal essentially not overlapping. The line terminating device according to the invention has a digital frequency separating filter in the digital section of the line terminating device, which is arranged in the digital section of the line terminating device so that the audio-frequency voice signal is separated from the higher-frequency data signal. In particular, the line terminating device is suitable for separating an ISDN or POTS voice signal from an ADSL data signal.

Abstract: The invention relates to a linear SC circuit arrangement using integrated deep submicron technology, having at least one switched capacitor circuit which is connected to an input for inputting an input signal and which has at least one switchable capacitor and at least one first transistor, having a control circuit for directly actuating the first transistors, having an output stage which has second transistors and which is arranged downstream of the switched capacitor circuit, where the first transistors are in the form of thick oxide transistors and have a higher withstand voltage than the second transistors.

Abstract: In the line terminating device, which is provided for transmitting and receiving narrowband low-frequency voice signals and broadband data signals at a higher frequency, the analog reception path is subdivided into two separate analog paths (32, 33) for voice and data using a balance filter (49), which is used for data signal echo cancellation. In the transmission direction, the voice signal path and the data signal path are separated in the digital part by means of digital filters (43, 45). The invention is used for voice and data signal separation in xDSL methods, for example, ADSL.Lite.

Abstract: The present invention relates to a circuit for electronically generating a call impedance in telephone terminals, comprising a call alternating voltage that may be tapped between a first and a second input terminal. The inventive circuit has a regulating device with a programmable digital filter for regulating impedance, wherein the transmission function of the regulating device can be adjusted by programming the filter coefficients of the digital filter. The inventive regulating device makes it possible to adapt the call impedance to different country-specific requirements. To this end, the regulating device has a programmable digital filter that may be embodied as a digital signal processor. In an especially preferred embodiment, the digital filter is implemented in the form of a program in the digital signal processor.

Abstract: Tone signal detection circuit for a receiving circuit for detecting at least one tone signal of predetermined tone signal frequency (fE) which is contained in a received analog input signal, comprising a reference signal generator (41) for generating an analog converter reference signal which consists of a reference DC (VrefDC) and a periodic reference AC (VrefAC) having a variable fundamental frequency (fG), which is superimposed on the reference DC, an analog/digital converter (11) for converting the analog input signal into a digital data stream in dependence on the analog converter reference signal (Vref); and comprising a digital control circuit (20) which adjusts the variable fundamental frequency (fG) of the reference signal (Vref) generated by the reference signal generator (42) in accordance with the predetermined tone signal frequencies (fG) of the tone signals to be detected and evaluates the digital data stream output by the digital analog/digital converter (11) for detecting a data pattern corres

Abstract: The invention relates to a circuit arrangement for forming the termination of an analogous subscriber line which comprises a first connection and a second connection for connecting a twin-wire analogous subscriber line. Said first connection is linked with said second connection via a series connection of a first capacitor, at least one first adjustable resistor and one second capacitor. According to the invention, a direct current source is linked with the first point of linkage of the first capacitor and the first adjustable resistor. Said direct current source impresses a current which serves to adjust an operating point for voice and data transmission via the analogous subscriber line. The first and the second capacitor block equisignals on the subscriber line so that no direct current can flow via the analogous subscriber line.

Abstract: The invention relates to an analog echo filter for a modem, to which an analog transmit signal is supplied. According to the invention, a passive analog input filter and an active analog filter, whose transfer function is adjustable, are provided. The transfer function of the active analog filter can preferably be switched between a first-order transfer function and a second-order transfer function.

Abstract: The invention relates to a linear SC circuit arrangement using integrated deep submicron technology, having at least one switched capacitor circuit which is connected to an input for inputting an input signal and which has at least one switchable capacitor and at least one first transistor, having a control circuit for directly actuating the first transistors, having an output stage which has second transistors and which is arranged downstream of the switched capacitor circuit, where the first transistors are in the form of thick oxide transistors and have a higher withstand voltage than the second transistors.

Abstract: 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 (110) is supplied to a mixing unit (201) and in the mixing unit (201), a receive noise signal (211) applied to a receive noise source terminal (209) is superimposed on the digital transmission signal (110). An interpolation filter unit (203), in combination with a subsequent noise shaping device (205), provides an increase in the frequency bandwidth, resulting in suitable oversampling.

Abstract: A digital-to-analog converter arrangement able to process input signals with different signal bandwidth is provided. The arrangement comprises a first input terminal for receiving a first digital input signal, a second input terminal for receiving a second digital input signal and switching means being coupled to the first and second input terminals and being adapted to select between the first and second digital input signals so as to output an intermediate digital signal corresponding to the selected one of the first and second digital input signals. The intermediate digital signal is received by an array of unary digital-to-analog converting elements, each unary digital-to-analog converting element being adapted so that, as an analog output signal, a sum signal of output signals of the unary digital-to-analog converting elements is output.

Abstract: A protective circuit for limiting a voltage at a pad of an integrated circuit includes a threshold selector connected between the pad and ground. The input voltage to the threshold selector is the pad voltage. The threshold detector includes a first transistor where load path is connected to the pad. The central terminal of the first transistor is maintained at a threshold voltage derived from the pad voltage. A second transistor has its control terminal connected to a second terminal of the load path of the first transistor. The load path of this second transistor is connected between the pad and ground.

Abstract: The invention relates to a circuit configuration for two-wire/four-wire conversion. The circuit configuration has a receiver which is coupled on an input side to a digital two-wire reception path via which its receives a digital signal. A signal-processor is connected downstream of the receiver and emits a first and second signal. An echo-canceling device receives the first signal and emits a third signal. A digital-to-analog converter is provided which receives the second signal and emits a fourth signal. A hybrid circuit is coupled to an analog four-wire transmission-reception path, receives the fourth signal, and emits a fifth signal. An analog-to-digital converter receives the fifth signal and emits a sixth signal. A transmitter receives the sixth signal and is coupled on an output side to a digital two-wire transmission path and emits a digital transmitted signal to the latter. In the invention, the digital-to-analog converter has a sigma-delta modulator.

Abstract: The invention relates to a circuit configuration for quantization of digital signals and for filtering quantization noise. Said circuit configuration comprises a multitude of digital control loops connected in series and having quantizers. The digital signals having a word length of m-bits are fed to a first control loop in the series. The quantization error signal of each quantizer is filtered and fed back to the corresponding digital control loop. It is then fed to a downstream digital control loop. The quantized output signal of the first digital control loop is adapted to a third word length of u-bits which is smaller than the first word length. Except for the quantized output signal of the first digital control loop, the quantized output signals of the digital control loops of the series are respectively filtered by a digital filter.

Abstract: 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.

Abstract: The present invention is related to an analog/digital converter which includes a multitude of integrating circuits, a 1 bit analog/digital converter and a 1 bit digital/analog converter. The multitude of analog integrating circuits are connected in series and the 1 bit digital/analog converter is connected downstream from the last analog integrating circuit of the series. An output signal of the 1 bit analog/digital converter is transmitted to the 1 bit digital/analog converter, and an output signal of the 1 bit digital/analog converter is subtracted from an input signal of each analog integrating circuit. A multitude of input signals is transmitted via a multiplexer to the first analog integrating circuit of the series-connected analog integrating circuits.