National Semiconductor Corporation

Devnath Varadarajan

Jitendra Mohan

Laurence Douglas Lewicki

Vijaya G Ceekala

Ramsin Michael Ziazadeh

James B Wieser

Abu-Hena Mostafa Kamal

Vjay Ceekala

An operational amplifier having a low impedance input and a high current gain output. The operational amplifier comprises: 1) a first N-channel transistor having a source coupled to the low impedance input of the operational amplifier; 2) a first constant current source coupled between the source of the first N-channel transistor and ground; 3) a first amplifier stage having an input coupled to the first N-channel transistor source and an inverting output coupled to a gate of the first N-channel transistor; 4) a second amplifier stage having an input coupled to a drain of the first N-channel transistor and an output coupled to the high current gain output of the operational amplifier; and 5) an internal compensation capacitor coupled between the input and the output of the second amplifier stage.

High speed high current gain operational amplifier

A band-gap reference circuit with averaged current mirror offsets is provided that includes a differential amplifier circuit, a low current transistor circuit, a high current transistor circuit, and a configuration circuit. The differential amplifier circuit includes a first input node operable to receive a first input signal, a second input node operable to receive a second input signal, and an output node operable to generate an output signal based on the input signal difference. The low current transistor circuit is coupled to the differential amplifier circuit and is operable to receive the output signal and to generate the first input signal based on the output signal. The high current transistor circuit is coupled to the differential amplifier circuit and is operable to receive the output signal and to generate the second input signal based on the output signal. The configuration circuit is coupled to the low current transistor circuit and to the high current transistor circuit. The configuration circuit is operable to configure the band-gap reference circuit for a plurality of states by switching a plurality of components between the low current transistor circuit and the high current transistor circuit at specified intervals.

Band-gap reference circuit with averaged current mirror offsets and method

An operational amplifier circuit with improved feedback factor is provided that includes an input impedance, an operational amplifier, and a current conveyor. The input impedance is operable to receive an input signal. The operational amplifier comprises an inverting input node, a non-inverting input node, and an output node. The operational amplifier is operable to generate an output signal at the output node based on the input signal. The current conveyor is coupled between the input impedance and the inverting input node of the operational amplifier. The current conveyor is operable to provide a low impedance to the input impedance and a high impedance to the operational amplifier.

Operational amplifier circuit with improved feedback factor

There is disclosed high-speed current-mirror circuitry and methods of operating the same. An exemplary impedance-peaking current mirror comprises a N-channel drive transistor and a N-channel mirror transistor. The N-channel drive transistor has a source coupled to ground, a drain coupled to a current source and a gate coupled to the drain via a series connection of a resistor and an inductor. The N-channel mirror transistor has a source coupled to ground, a gate coupled to the drain of the N-channel drive transistor, and a drain coupled to a positive power supply via an impedance load.

High-speed current-mirror circuitry and method of operating the same

An RC calibration circuit, which utilizes a resistor and a variable capacitor connected in parallel, reduces power consumption and increases the accuracy of the calibration by comparing the voltage on the resistor to the voltage on the capacitor after a predetermined time has expired since the capacitor began charging up. The result of the comparison, which indicates whether the voltage on the resistor is greater than the voltage on the capacitor, is then used to adjust the capacitance of the capacitor to servo the RC time constant to a predetermined value.

RC calibration circuit with reduced power consumption and increased accuracy

A line driver outputs a pair of transmit signals TX&plus; and TX&minus; that have substantially reduced output level variations due to variations in process, voltage, and temperature. The reduced output level variations are provided by varying the magnitude of the current that sets up the voltages of the transmit signals in a manner that offsets variations in the power supply voltage, temperature, and process, and by limiting variations of the bandgap current source to process and temperature only.

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Santa Clara, CA, United States of America

Devnath Varadarajan