National Semiconductor Corporation

Varadarajan Devnath

Ramsin Michael Ziazadeh

James B Wieser

Vijaya G Ceekala

Alan Erik Segervall

Jitendra Mohan

Yongseon Koh

Lawrence K Whitcomb

Quyet Nguyen

A method and apparatus for a Gigabit Ethernet transceiver that has a Class-B amplifier in a main transmitter for higher efficiency and power handling capabilities. The output current of the main transmitter is produced by a reference voltage applied across a resistor, where the reference voltage generator, resistor and amplifier are fabricated on the same substrate, such that the output current is constant across process voltage and temperature. The transceiver also has a replica transmitter whose signal is used to cancel the main transmitter signal at the input of the receiver section of the transceiver. The replica transmitter is fabricated on the same substrate as the main transmitter, such that its output signal reflects non-linearities in the main transmitter across process voltage and temperature.

Class-B transmitter and replica transmitter for gigabit ethernet applications

A skew measurement system and method wherein each of the signals among which the skew is to be determined is connected one at a time to a clock recovery loop. The locked state of the clock recovery loop is used as an indicator of the skew of the data signal relative to the internal clock of the clock recovery loop. By measuring the difference between the locked state of different signals, their relative skew can be measured.

Apparatus and method for skew measurement

A serial communication interface driver is provided wherein current steering switches are also used to provide termination impedances. The output voltage can be produced by a voltage-dividing current path between two regulated voltages, which provides improved efficiency.

Voltage mode serial interface driver with PVT compensated impedance

A tunable impedance circuit is provided wherein at least one of a plurality of impedance elements is combined with at least another of the plurality of impedance elements to produce a composite impedance. A control voltage is used to determine how many of the impedance elements are to be combined to produce the composite impedance. A current that is substantially invariant over a range of operating conditions is caused to flow through a control impedance to produce the control voltage.

Tuning control for a PVT-compensating tunable impedance circuit

An H-bridge LVDS driver circuit includes a means to calibrate the output impedance of the switches of an LVDS driver to any desired value.

Circuit and method for impedance calibration of output impedance of LVDS driver

Integrated differential data signal generator circuitry for providing differential data signals with controlled rise and fall times and built-in test capabilities.

Differential signal generator having controlled signal rise and fall times with built-in test circuitry

A circuit and method for generating quadrature signals with a deterministic phase relationship. Between two inductive-capacitive (LC) based quadrature voltage controlled oscillators (VCO), phase shift circuitry is interposed such that the individual LC VCO circuits produce signals with corresponding phase delays which ensure that the desired lead or lag phase relationship between the quadrature signals is achieved.

Inductive-capacitive (LC) based quadrature voltage controlled oscillator (VCO) with deterministic quadrature signal phase relationship

A transimpedance amplifier with controllable noise reduction in which DC offsets due to the input signal are tolerated during reception of low input signals by reducing, e.g., terminating, a compensation current to remove a dominant source of thermal noise, but compensated during reception of higher input signals where the effects of DC offsets are more dominant.

Transimpedance amplifier with controllable noise reduction

A programmable differential current mode line driver with multiple classes of circuit operation that can be digitally programmed to operate in a low distortion, low noise class A mode or a low power class B mode, with multiple signal levels available in each mode of operation.

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Santa Clara, CA, United States of America

Varadarajan Devnath