Lucent Technologies Inc.

Agere Systems Guardian Corp.

Kouros Azimi

Dale Harvey Nelson

Jonathan Herman Fischer

Bahram Ghaffarzadeh Kermani

Zhigang Ma

Oceager P Yee

Brian J Petryna

Tseng-Nan Tsai

A highly accurate tuning circuit for a tunable filter is provided which trims an RC time constant based on variances in both a formed capacitive component as well as variances in formed resistive components. A capacitor and resistor based tuning control circuit includes both a formed capacitor based tuning reference current generator and a formed resistor based tuning voltage reference generator. Each generates a voltage reference which is compared to the other to determine control signals for tuning a tunable resistive component forming the resistive portion of the RC time constant of the relevant filter. The resistive component is tuned by shorting selective resistors in the tunable resistive component. By tuning the RC time constant to the particular variances in capacitor and resistor components formed in the integrated circuit, the RC time constant of the tunable filter can be tuned to a desired absolute value within a tighter tolerance range than was previously available with conventional tuning circuits which provided tuning control based only on the variances of formed resistor elements.

Method and apparatus for tuning filters

An apparatus and method for reducing variations in a supply voltage signal. The voltage signal which powers a circuit is regulated by adding or removing a series of redundant loads to the circuit. The redundant loads are normally not connected to the circuit. However, when one of the loads of the circuit is switched out of the circuit, one or more of the redundant loads are switched into the circuit, and then removed gradually from the circuit. When one of the loads of the circuit is to be switched into the circuit, one or more of the redundant loads are switched into the circuit first, then switched out of the circuit when the load is switched in. Thus, the voltage supply sees almost the same load during a turn-on and turn-off transition period, and variations in the voltage signal are reduced.

Reduced impact power up/down mode in electrical circuits

A multifunction reset circuit including low power bandgap, a comparator, and an open drain buffer circuit--with the inclusion of four external components (three resistors and one capacitor) to provide undervoltage monitoring, power failure indicating, manual resetting and other reset control conditions to a single integrated circuit terminal, together with hysteresis tolerance.

Multifunction reset for mixed-signal integrated circuits

An integrated circuit comprising a balanced differential amplifier. The balanced differential amplifier has a first single-ended differential amplifier coupled at a first negative differential input terminal to a first input signal through a feedback network also coupled to an output terminal of the first amplifier. The first amplifier is also coupled at a first positive differential input terminal to a second input signal through a first resistor and to a reference voltage. The balanced differential amplifier also has a second single-ended differential amplifier coupled at a second negative differential input terminal to the second input signal through a second feedback network also coupled to an output terminal of the second amplifier. The second amplifier is also coupled at a second positive differential input terminal to the first input signal through a second resistor and to the reference voltage.

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West Chester, PA, United States of America

Kouros Azimi