Abstract: An integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop is disclosed. The integrated circuit processes the sensed signals to generate an analog control signal for a subscriber loop linefeed driver. The linefeed driver does not reside within a same integrated circuit.

Abstract: An integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop is disclosed. The integrated circuit processes the sensed signals to generate a control signal for a subscriber loop linefeed driver.

Abstract: An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier.

Abstract: An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier.

Abstract: A subscriber line interface circuit apparatus includes a signal processor having sense inputs for sensed tip and ring signals of a subscriber loop. The signal processor generates linefeed driver control signals in response to the sensed signals. A linefeed driver provides the sensed tip and ring signals. The linefeed driver drives the subscriber loop in accordance with the linefeed driver control signals.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end that provides a communication path for signals to and from the phone lines. Briefly described, the DAA provides a programmable means for the DC termination for a variety of international phone standards. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DC holding circuit is provided in which a programmable DC current limiting mode is available. In the current limiting mode, power may be dissipated in devices external to a DAA integrated circuit. Moreover, much of the power may be dissipated in external passive devices, such as resistors.

Abstract: An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier.

Abstract: Subscriber line interface circuitry includes an integrated circuit having sense inputs for a sensed tip signal and a sensed ring signal of a subscriber loop. The integrated circuit generates a subscriber loop linefeed driver control signal in response to the sensed signals. In one embodiment, A linefeed driver includes power circuitry for providing battery feed to the ring and tip nodes of the subscriber loop in accordance with the linefeed control signal. The linefeed driver includes sense circuitry providing a sensed tip signal and a sensed ring signal. The sensed tip and ring signals correspond to a tip current and a ring current of the subscriber loop. In one embodiment, the integrated circuit is a complementary metal oxide semiconductor (CMOS) integrated circuit. In one embodiment, the linefeed driver comprises only discrete components.