International Standard Electric Corporation

Nortel Networks Corporation

Sige Semiconductor, Inc.

Edward J Whittaker

Gordon Glen Rabjohn

Johan M Grundlingh

Peter F Blomley

Kenneth A Arton

Andrew Paul Lefevre

Paul Wilson

Kenneth Searle

Darrell Smith

Imran Sherazi

A bias control circuit is provided comprising an input port for receiving a signal indicative of an amplitude of a supply voltage provided to a multi stage power amplifier circuit. Electronic circuitry, electrically coupled to the input port, generates a bias control signal in dependence upon the signal indicative of a supply voltage for provision to a first stage power amplifier of the multi stage power amplifier circuit. The bias control signal is generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated.

Gain control for linear radio frequency power amplifiers

A collector boost circuit is disclosed for providing a first voltage in a first mode of operation to a power amplifier, and another voltage in a second mode of operation to the power amplifier. The collector boost circuit uses an indicator signal derived by an RF detector to switch between the first and the second mode of operation. The another voltage is a boosted voltage greater than the first voltage and is provided when required during peak excursions to prevent amplifier clipping through a boost capacitor. The another voltage is continuous and varies in accordance with the detected peak signal amplitude.

Integrated implementation of a voltage boost follower and method therefor

An optical receiver arrangement comprises a phase locked loop incorporating a voltage controlled oscillator whereby the loop can be matched in frequency to a received signal frequency. A frequency detector associated with the loop produces an output comprising first or second pulses indicative of whether the loop frequency is above or below the received signal frequency. A control circuit determines a time averaged measure of difference between the loop frequency and the received signal frequency, and issues a loss of lock alarm if this averaged difference exceeds a predetermined value.

Method and arrangement for clock and data recovery

An interface circuit from Common Mode Logic to a low voltage, fixed common mode output, with high current drive. The CML signal is received, and then re-referenced to a low-voltage band-gap supply. The circuit is arranged to provide an output data signal referenced to a second positive reference voltage supply responsive to receipt of a common mode input data signal referenced to a first positive reference voltage supply. The circuit avoids use of vertical PNP transistors in the signal path.

High speed level shift circuit for low voltage output

In a loudspeaking telephone the power supply to the loudspeaker amplifier is shunted by a regulator which functions as a programmable Zener diode. Under conditions of low available line current, e.g. where two similar instruments are operated in parallel at the end of a long line, the regulator voltage is reduced in value to disable the amplifier and conserve power to maintain the basic operating functions of the telephone.

Shunt regulator for hands-free telephone

A transmission chip for a telephone subscriber's instrument can be used in a variety of modes, some of which involve use with other chips. Depending on which mode is in force, different amplifiers are used. Thus for plain ordinary telephone (POT) service, amplifiers 30,35 and 43 are used, for loudspeaking mode amplifiers 30, 35 and 43 are used, for handsfree use amplifiers 35, 43 and 46 are used, while for VF 'dialling' amplifier 46 is used. To save power, the control block (42) detects the mode in which the set is operating and, via a control bus, operates electronic switches to disable the amplifiers not needed.

Telephone subscribers' circuits

An integrated circuit for a telephone instrument provides the basic (POT) service requirement. The transmit and receive channels of the circuit may be fed via controlled attenuators incorporated in a first ancillary circuit to provide hands-free operation. The circuit also includes a current-limited power supply whereby connection to a second ancillary circuit, including an audio amplifier, may be effected to provide loudspeaker operation.

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Bishops Stortford, United Kingdom

Edward J Whittaker