Abstract: A method and apparatus for a telephone line interface or data access arrangement (DAA) which includes a shunt regulator in series with a line modulator. A sense resistor is placed in series between the shunt regulator and the line modulator to provide a measurement of the amount of current distortion in the DAA. The line modulator contains a Darlington pair which reduces the amount of current drawn by the line modulator, allowing the sense resistor to sense a majority of the system current. The voltage across the sense resistor is fed back to the line modulator. The line modulator is capable of adjusting the AC modulation and the DC termination presented to the telephone line. The method includes drawing power from the telephone line using a shunt regulator, modulating the telephone line in series with the shunt regulator, sensing a level of distortion in the DAA, and feeding the sensed level of distortion to the line modulator.

Abstract: A line powered data access arrangement (DAA) is disclosed which adaptively allows proper operation with power supplied from a telephone line as conditions warrant, while at the same time satisfying the relevant requirements of many countries. In the line powered codec, a startup procedure for the international line powered codec uses register settings, e.g., country-specific register settings, which are powered and maintained from the low voltage side (e.g., from the PC or modem side) of the line powered codec. In this way, even during low line power conditions the programmed state of the line powered codec can be maintained, thus a default condition will not necessarily returned to by the line powered codec upon reset due to a power loss in the telephone line. In another aspect, a charge storage device such as a charge capacitor is charged from a charge pump formed from a differential clock signal from the low voltage side.

Abstract: A telephone line interface or data access arrangement (DAA) is provided which draws power for the customer premises equipment from the telephone line. The DAA includes a shunt regulator as the power source drawing power from the telephone line, and a line modulator in series with the shunt regulator. A sense resistor is placed in series between the line modulator and shunt regulator to sense the line current. Accordingly, DC termination and AC modulation characteristics as presented by the DM to the telephone line can be adjusted by variation of an AC signal with DC offset input to the amplifier driving the line modulator without requiring a different DAA for use in regions or countries having various DC termination and AC modulation requirements. The differential feedback from a sense resistor reduces the noise induced in the circuit from the shunt regulator.

Abstract: A method and apparatus for a data access arrangement (DAA) which includes a line modulator containing capacitive elements to increase system stability. The invention provides improved stability during system startup and normal system operation. The line modulator is capable of adjusting the AC modulation and the DC termination presented to the telephone line. Capacitive elements are added to the modulator to provide enhanced system stability. The method includes drawing power from the telephone line, modulating the telephone line, sensing a level of distortion through the line modulator, feeding the sensed level of distortion to the line modulator, and using capacitive circuits to provide additional system stability.

Abstract: A circuit provides a modulation signal to an input terminal of a line modulator which places a line current modulated in accordance with the modulation signal on a telephone line. An amplifier of the circuit amplifies an analog input signal to provide the modulation signal at an output terminal. A first resistor and a first capacitor are coupled in series between a first input terminal of the amplifier and the line, and a second resistor and a second capacitor are coupled in series between a second input terminal of the amplifier and the line. First and second precharge amplifiers are used to precharge the first and second capacitors, respectively, to reduce DC setup time.

Abstract: A telephone line interface or data access arrangement (DAA) is provided which draws power for the customer premises equipment from the telephone line. The DAA includes a shunt regulator as the power source drawing power from the telephone line, and a line modulator in series with the shunt regulator. A sense resistor is placed in series between the line modulator and shunt regulator to sense the line current. Accordingly, DC termination and AC modulation characteristics as presented by the DM to the telephone line can be adjusted by variation of an AC signal with DC offset input to the amplifier driving the line modulator without requiring a different DAA for use in regions or countries having various DC termination and AC modulation requirements. The differential feedback from a sense resistor reduces the noise induced in the circuit from the shunt regulator.

Abstract: A telephone line interface or data access arrangement (DAA) includes a shunt regulator in series with a line modulator. A sense resistor is placed in series between the shunt regulator and line modulator to provide a measurement of an amount of noise in the DAA shunt regulator, which is fed back to the line modulator. The line modulator is capable of adjusting the AC modulation and DC termination presented to the telephone line. The method includes drawing power from the telephone line using a shunt regulator, modulating the telephone line in series with the shunt regulator, sensing a level of noise in the shunt regulator, and feeding back the sensed level of noise to the line modulator.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: The number of separate signals necessary in a serial interface are reduced by combining a transmit data signal with a clock signal having a rate equal to a multiple of a bit rate of the transmit data signal, before encoding for transmission. The number of separate signals in a serial interface may be reduced further by sigma-delta (&Sgr;/&Dgr;) encoding the transmit data into 1-bit samples, thus eliminating the need for a frame sync signal. By combining the transmit data with a higher rate clock signal, jitter in the recovered clock signal at the receiving end is greatly reduced or even eliminated. At the receiving end, the higher speed clock is recovered at the multiplied rate, used to latch the transmit data from the combined data and higher clock signal, and divided back to the data rate to provide an original bit clock along with an original transmit data signal.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: A method and apparatus to receive and demodulate call related information, e.g., Caller ID information, in an audio codec placed on the line side and powered by current drawn from the telephone line. The audio codec includes a 1st order &Sgr;/&Dgr; A/D converter to digitize the signal from the telephone line with &Sgr;/&Dgr; modulation. The 1st order &Sgr;/&Dgr; A/D converter may be a scaleable component capable of alternative operation in a 2nd order. The &Sgr;/&Dgr; encoded digitized signal is digitally processed by a DSP including an amplifier module, a digital filter, a limit/slice module, and an FSK decoder to receive and output the call related information. Placement of the audio codec on the line side and the scaleable &Sgr;/&Dgr; A/D converter provides significantly reduced power requirements for the audio codec, thus allowing operation from power derived from the telephone line.

Abstract: The present invention provides a method for interlocking a connector for a communication card including a first connection portion for connection to signals in the communication card relating to a first device such as a cellular telephone. A second connection portion in the interlocking connector provides for connection to signals in the communication card relating to a second device such as the PSTN. A blocking portion of the interlocking connector prevents electrical connection with the second connection portion and allows electrical connection with the first connection portion when the interlocking connector is connected to the communication card. A communication card is also provided which comprises modem circuitry, and an interface for connection between the modem circuitry and a computing device. A PSTN interface is provided for connection between the modem circuitry and a telephone line, and a cellular telephone interface is provided for connection between the modem circuitry and a cellular telephone.

Abstract: The present invention provides an interlocking connector for a communication card including a first connection portion for connection to signals in the communication card relating to a first device such as a cellular telephone. A second connection portion in the interlocking connector provides for connection to signals in the communication card relating to a second device such as the PSTN. A blocking portion of the interlocking connector prevents electrical connection with the second connection portion and allows electrical connection with the first connection portion when the interlocking connector is connected to the communication card. A communication card is also provided which comprises modem circuitry, and an interface for connection between the modem circuitry and a computing device. A PSTN interface is provided for connection between the modem circuitry and a telephone line, and a cellular telephone interface is provided for connection between the modem circuitry and a cellular telephone.