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: A class D-amplifier which amplifies an input signal applied to an signal input of said amplifier (21) to generate an amplified signal output by an signal output (28a, 28b) of said amplifier comprising a comparator (23) which compares the applied input signal with a switch signal to generate a pulse width modulated signal; a driving unit (24) which amplifies the pulse width modulated signal to generate the amplified output signal; and a feedback circuit which generates the self oscillating switch signal for the comparator (23).

Abstract: A class D-amplifier which amplifies an input signal applied to an signal input of said amplifier (21) to generate an amplified signal output by an signal output (28a, 28b) of said amplifier comprising a comparator (23) which compares the applied input signal with a switch signal to generate a pulse width modulated signal; a driving unit (24) which amplifies the pulse width modulated signal to generate the amplified output signal; and a feedback circuit which generates the self oscillating switch signal for the comparator (23).

Abstract: Broadband xDSL transceiver for transmitting and receiving signals in a predetermined broadband frequency range (?F) via a signal line which has a complex line impedance (ZL), wherein the xDSL transceiver (1) comprises a line driver (3) for driving a transmission signal applied to a signal input (4a, 4b) of said line driver (3) via said signal line; a receiver (8) for evaluating a reception signal received via said signal line and applied to a signal input of said receiver (8); an echo canceling bridge (10) for canceling the transmission signal at the signal input (9a, 9b) of said receiver (8); a sense impedance (11) connected to the signal line; a feedback resistor network (15a, 15b) provided between the sense impedance (11) and the signal input (4a, 4b) of said line driver (3) performing a synthesized termination impedance (ZT) of the xDSL transceiver (1) as a product of the sense impedance and an impedance synthesis factor (G); wherein the sense impedance (11) is a complex impedance (ZS) so that the

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: Line driver arrangement comprising a class-D switching amplifier having a switching frequency for receiving an input transmit signal and outputting an amplified transmit signal and a transformer having a predetermined leakage inductance for receiving the amplified transmit signal and outputting a transform signal as an output transmit signal. The leakage inductance is predetermined for low-pass filtering of the amplified transmit signal. The line driver arrangement reduces the number of additional discrete inductances, capacitances and or resistor for forming low-pass filters significantly. The inventive line driver arrangement is particularly power-efficient due to the included class-D switching amplifier. The predetermined leakage inductance leads to a suppression of a resonance due to the switching frequency of the class-D amplifier in the power spectral density. Hence, the inventive line driver arrangement complies at least with the ADSL PSD mask requirements.

Abstract: A ringtrip detector comprises a reference counter for controlling a battery current generator, which shapes the ring signal, a zero pass detector for detecting zero passes in a voltage at a node, which is proportional to the telephone line current and two other counters. The zero passes of the voltage create a pulse at both the positive and the negative zero crossing of the zero pass detector. The reference counter is gated into a memory, when these pulses appear. The zero passing of the previous and the present ring cycle are stored in the memory. A counter decides the difference between the previous and the present ring cycles zero passes. If the zero pass difference between the present and previous ring cycles is greater than a fixed value, the output will indicate a "phase difference" and if it is less than the fixed value it will indicate "no phase difference".