DAVID ROSS THOMAS
Pilots at Black Willow Dr, Apex, NC

6275583, Aug 14, 2001

Mar 25, 1998

9/047985

Jeffrey Haskell Derby - Chapel Hill NC
David Ross Thomas - Apex NC

International Business Machines Corporation - Armonk NY

H04M 322, H04M 1100

379412

A network interface circuit includes an off-hook/on-hook circuit, responsive to the communications network, that provides an off-hook voltage substantially equal to the communications network voltage in an off-hook state and that provides an on-hook voltage in an on-hook state. A voltage controlled current source provides a load current which is proportional to a communications network voltage provided by the communications network. A divider circuit, responsive to the off-hook/on-hook circuit, provides an input voltage and produces an over-voltage, wherein the input voltage is proportional to off-hook or on-hook voltage. A clamping circuit limits the input voltage to one of a first or second predetermined value based on the operating mode and generates a current limited voltage. A control circuit, responsive to the over-voltage and the current-limited voltage and the operating mode and responsive to the off-hook/on-hook circuit, sets the network interface circuit in the off-hook state or the on-hook state based on the input voltage, the current-limited voltage, and the operating mode. Related methods and apparatus are also discussed.

6181792, Jan 30, 2001

Jan 23, 1998

9/013363

Jeffrey Haskell Derby - Chapel Hill NC
David Ross Thomas - Apex NC

International Business Machines Corporation - Armonk NY

H04M 176

379398

A communication interface and a design method therefor provide a synthesized terminating impedance matching different frequency bands on a communication circuit. In some cases, for example based on specified network requirements in a particular country, the terminating impedance presented by the interface must have different frequency characteristics for received signals in different bands of frequencies. A transconductance amplifier and feedback loop provide the terminating impedance for signals received from the communication circuit and serves as a source impedance for signals transmitted by the interface to the telephone line. Signals with different frequencies will generally be received from the telephone line. These different characteristics are realized using different filter networks in the feedback loop. Each network provides a matching terminating impedance to the communication circuit according to the frequency band applied to the circuit.

6198817, Mar 6, 2001

Jan 23, 1998

9/012311

Jeffrey Haskell Derby - Chapel Hill NC
David Ross Thomas - Apex NC

International Business Machines Corporation - Armonk NY

H04M 160

379394

A communication interface and a design method therefor simultaneously shape a synthesized terminating impedance matching different frequency bands on different connecting communication circuits and a receive path response to prevent frequency roll-off. In some cases, for example based on specified network requirements in a particular country, the terminating impedance presented by the interface must have different frequency characteristics for received signals in different bands of frequencies. A transconductance amplifier and feedback loop provide the terminating impedance for signals received from the communication circuit and serve as a source impedance for signals transmitted by the interface to the telephone line. Signals with different frequencies will generally be received from the telephone line. These different characteristics are realized using different filter networks in the feedback loop.