Intersil Americas Inc.

Harris Corporation

Intersil Corporation

Douglas Lawton Youngblood

Leonel Ernesto Enriquez

Edward A Berrios

Christopher Ludeman

Robert W Webb

Vijayakumar Dhanasekaran

Donald Giles Koch

Roger Levison

Steven R Smith

A voltage regulator circuit arrangement limits the DC voltage applied to a tip and ring amplifiers of a subscriber line interface circuit (SLIC), each of which has a first polarity input coupled to a first current flow path to which a DC input (battery) voltage is coupled. A first current source supplies a first current derived via a low pass filter path from that flowing through the first current flow path to a second polarity input node of the tip amplifier, while a second current source supplies a similarly low pass filter path-derived second current to a second polarity input node of the ring amplifier. A voltage regulator is coupled with the first current flow path and is operative to regulate the voltage at the first polarity inputs of the tip and ring amplifiers to a regulated voltage value Vreg, so that the magnitudes of the first and second currents are based upon the regulated voltage value Vreg.

Active mode line voltage regulator for ringing subscriber line interface circuit

A subscriber line interface circuit has a battery-powered, high voltage analog section, that drives tip and ring lines of a subscriber loop, and a mixed signal (low voltage and digital signal processing) section, that monitors and controls the high voltage analog section. An input signal receiving unit of the high voltage analog section conditions input voice and low voltage signaling and ringing signals from the mixed signal section, for application to a dual mode, programmable gain, tip/ring amplifier coupled to the loop. A sense amplifier at the output of the tip/ring amplifier is through an auxiliary amplifier to an analog feedback monitor port for closing a loop to synthesize the circuit's output impedance.

Programmable subscriber line circuit partitioned into high voltage interface and digital control subsections

A switch circuit including a first switch, a reference device, a current generating device and a comparator. The first switch has a first resistance and develops a first voltage when a first current is provided through it. The reference device has a second resistance which is a known multiple of the first resistance. The current generating device provides a reference current through the reference device which develops a second voltage having a level indicative of a maximum current level of the first current. The comparator compares the first and second voltages and provides a maximum current indication. An amplifier may be used to force one side of the first switch and the reference device to the same voltage, where the reference device is coupled between an input and an output of the amplifier. The switch circuit may include a calibration mode.

Analog switch with overcurrent detection

A MOSFET-based, multi signal-switching circuit controllably passes analog/audio signals and digital signals through a common terminal to a single connector. Analog/audio signals are coupled through a single N-channel MOSFET analog signal switch which, when turned-ON, minimizes distortion of the analog/audio signal and capacitive loading to an adjacent, MOS-based or CMOS-based digital data signal switch. A respective turn-OFF circuit maintains its associated switch MOSFET turned OFF.

Method and apparatus for switching audio and data signals through a single terminal

A multiple channel programmable gamma correction voltage generator including a resistor ladder, buffers, select logic, and a programmable non-volatile memory device. The memory provides select values indicative of one or more stored gamma correction values. The resistor ladder includes adjustable tap resistors distributed along the resistor ladder. The adjustable tap resistors provide multiple tap voltages distributed according to the gamma correction value. The buffers receive the tap voltages and provide gamma correction voltages. The select logic selects tap points of the adjustable tap resistors to select the tap voltages based on the select values stored in the memory. Additional resistors and switch logic may be included to enable re-positioning of the adjustable tap resistor within the resistor ladder. Latches and address control may be provided on the memory to enable programming and selection of multiple gamma correction values.

Multiple channel programmable gamma correction voltage generator

A digitally configurable multiplexer/de-multiplexer including several multiplexers, a switch matrix, and configuration logic. Each multiplexer receives multiple address signals, selects from among multiple first data signals and couples a selected first data signal to a corresponding one of several multiplexed signals. The switch matrix has a first interface coupled to the multiplexed signals and a second interface coupled to multiple second data signals. The configuration logic receives selection signals and controls the switch matrix to couple selected ones of the multiplexed signals to the second interface.

Digitally configurable multiplexer/de-multiplexer

A mode-dependent, battery-coupling switch for a subscriber line interface circuit (SLIC) selectively adjusts its current requirements to provide optimal current handling capability irrespective of the mode of operation of the SLIC. Where current demands of the SLIC are relatively minimal (e.g., on-hook idle mode), the bias is set at a relatively small, default value. During high current demand, such as ringing and off-hook signaling, the bias is set at a relatively large value, to maintain a low voltage drop across the battery-coupling switch.

Mode-dependent, multiple bias-driven battery switch for subscriber line interface circuit

A differential amplifier circuit which amplifies a signal developed by a signal generating device when coupled between first and second input nodes and provides an amplified differential signal at first and second output nodes. First and second current sources source first and second current levels to the first input node and the first output node, respectively. First and second current sinks sink the first and second current levels from the second input node and the second output node, respectively. A first current amplifier controls current between the first output node and the second input node to maintain the second input node at a first bias voltage level. A second current amplifier controls current between the first input node and the second output node to maintain the first input node at a second bias voltage level. An optional feedback circuit senses a DC offset and adjusts current to compensate.

True differential microphone amplifier

A subscriber line interface circuit contains a high voltage analog section, and a low voltage and digital signal processing section, that monitors and controls the high voltage analog section. The high voltage analog section includes a dual mode tip/ring amplifier unit coupled to a subscriber loop pair, and an input signal receiving unit, that conditions input voice and low voltage signaling and ringing signals from the mixed signal section. Attributes of and/or enhancements to the high voltage section are used to improve the operational performance of the subscriber line interface circuit, in particular, low noise, low power, wide-bandwidth and wide dynamic range characteristics.

Enhanced high voltage interface for partitioned subscriber line interface circuit

A subscriber line interface circuit (SLIC) for a subscriber loop includes a pair of output amplifiers for connection to the subscriber loop and a transient output current limit circuit. The transient output current limit circuit may have at least one programmable output current limit and limit respective output currents from the pair of output amplifiers based thereon. The transient output current limit circuit may limit both source and sink currents for each of the pair of output amplifiers.

Subscriber line interface circuit (SLIC) including a transient output current limit circuit and related method

A voltage-coupling and loop current supply mechanism controllably turns on an output transistor within the tip amplifier circuitry portion of the speech amplifier to controllably apply a prescribed voltage to the telephone line during on-hook/standby mode. This controllably applied voltage serves as a source of loop current when the phone goes off-hook. The ring lead portion of the tip/ring wireline pair is connected to a controlled current sink, which is coupled to the output of a voltage regulator referenced to the battery voltage. This controlled current sink is used to sink a prescribed loop current from the tip/ring pair when the phone goes off-hook. When the phone goes off-hook and loop current is detected, the voltage-supply mechanism provided by the tip amplifier's output transistor is terminated, and the speech amplifier is placed in its normal speech amplifier mode.

Speech amplifier-resident mechanism for controllably supplying power to a line circuit

A CMOS-implemented transconductance amplifier has an input gain stage coupled to a CMOS output stage. The inverting input of the input gain stage is coupled to an input/output port to which an input voltage is coupled. The CMOS output stage has a first, transconductance CMOS transistor pair, whose source-drain paths are series-coupled between first and second outputs of the input stage. A second, transimpedance CMOS transistor pair have their source-drain paths series-coupled between first and second power supply terminals, and gate inputs coupled to outputs of the input stage. A third CMOS transistor pair is coupled in parallel with the second CMOS transistor pair to form a pair of current mirror stages. The current output is coupled to a common connection of the third CMOS pair.

Growing community of inventors

Palm Bay, FL, United States of America

Douglas Lawton Youngblood