Nortel Networks Corporation

Apple Inc.

Graham Dolman

Martin O'Flaherty

Paul Murray Row

Scott T Widdowson

Philip Holder

Dean Kitchener

Scott Widdowson

Andrew John Booth

Gregory John Bowles

John Ilowski

Christopher John Reed

David Neil Adams

Howard James Smith

Noureddine Outaleb

Dorian Davies

Mark Watkins

Fraser Murray Edwards

William Waddoup

Ken Trayling

Richard Emmerson

Simon Bates

Christopher J Adams

Peter King

Colin McGregor

Widdowson Scott

A broadband antenna structure has an electrically conductive enclosure with a closed end, over which a non-electrically conductive cover is placed. A radiating portion of an antenna feed layer comprising a conductive patch antenna element is placed in between the enclosure and the cover. The patch antenna element design is inherently broader band than that of conventional cavity-backed slot-radiating antennas, which are constrained in bandwidth by the need to keep the cavity formed in the enclosure small. The dielectric constant of the dielectric material of the cover reduces the required size of the conductive antenna element. The broadband antenna structure may be connected with an electronic device to form an antenna arrangement in which a portion of the antenna feed layer extends through an opening in a surface of an antenna housing, the portion being within an electronic device enclosure of the electronic device.

Antennas

A transmit chain comprises a transmit path with a quadrature up-converter which up-converts quadrature signal components to RF. An observation path samples a portion of the RF signal and a quadrature down-converter down-converts the RF signal to baseband quadrature signal components. A local oscillator signal source provides the up-converter and the down-converter with a local oscillator signal and is operable in two states. In a second of the states the local oscillator signal is applied to the up-converter and the down-converter and a phase shift is made to the signal applied to up-converter or the down-converter compared to the first of the states. A processor monitors properties of the down-converted signal while the local oscillator signal source is operating in the first state and the second state. The processor calculates a correction to apply to the baseband observation signal to correct for errors introduced by the observation path. The processor also calculates a correction to apply to the input signal to correct for errors introduced in the transmit path.

Measuring and correcting errors in a transmit chain with an IQ up-converter and IQ down-converter

A linearized power amplifier including a predistorter and a feedforward circuit is described. By using both a predistorter and a feedforward cancellation system the linearization of the amplifier is increased. The accuracy of the amplified signal may be further improved by training the predistorter using the error signal produced by the feedforward cancellation system. Improved accuracy in the linearizer results in a reduction in the power requirement of the error amplifier and a relaxation in the phase, amplitude and delay accuracy of the feedforward loop.

Linearised power amplifier

An enhanced Doherty-configured amplifier that features separate and independent bias voltage sources for the main and auxiliary amplifiers. The bias voltage sources may be controllable and variable to alter the performance of the amplifier according to the input signal or system requirements. The enhanced amplifier includes a signal preparation unit to divide and shape the input signal in order to compensate for non-linearities in the combined output signal.

Doherty amplifier with drain bias supply modulation

A time division duplex (TDD) wireless apparatus includes a low noise amplifier (LNA) system, at least one antenna and a transceiver system. The apparatus supports N time division duplexed channels which each have a transmit direction of transmission flow and a receive direction of transmission flow. The LNA system comprises N sub-units. Each sub-unit comprises a first circulator for connecting to a respective TX/RX feed to the transceiver system and a second circulator for connecting to the at least one antenna. The first circulator and second circulator within each sub-unit are interconnected to provide a path in one of the directions of transmission flow. The first circulator of each sub-unit is connected to the second circulator of another sub-unit to provide a path in the other direction of transmission flow. A single channel variant is also provided.

Stand-alone low noise amplifier

A modulated power supply comprises a power switching stage having at least one power switching device for generating a power signal in response to an input modulating signal. A current source is positioned in parallel with the power switching stage and continuously generates an output current. An output stage combines the power signal and the output current to form an output power supply signal. The current source supplies some, or all, of the required current at any given time. The switching device in the power switching stage either supplies the remaining required current or sinks any excess current. This has an advantage of reducing the average and peak currents flowing through the switching device, and hence the average power dissipation in the device. The output current can be set at an average (e.g. RMS) value of the current in the output power supply signal.

High efficiency modulated power supply

A predistortion power amplifier architecture has a power amplifier which receives an input via an amplitude modulator and a phase modulator. A sample of the output of the amplifier and a sample of the input to the amplifier are applied to an adaptive pre-distorter subsystem. The adaptive pre-distorter generates a gain correction signal which is applied to the amplitude modulator and a phase correction signal which is applied to the phase modulator. This serves to predistort the input signal to the power amplifier to compensate for non-linearities in the power amplifier. A switching arrangement alternately couples a sample of the input and output of the amplifier to a first and a second envelope detector. The outputs of the envelope detectors are applied to a difference amplifier. The switching arrangement has a chopping action on the signals which helps to offset imbalances in the characteristics of the two envelope detectors.

Amplitude and phase comparator for microwave power amplifier

Linear power amplifiers tend to be inefficient. This is a particular problem for RF amplifiers in a cellular base station. In order to improve the efficiency of such amplifiers, attempts have been made to modulate the power supply to the amplifier proportional to the envelope of the signal to be amplified. An UMTS signal requires power supply modulation at frequencies of the order of 10 to 20 megahertz. When quantization noise is taken into account, oversampling becomes desirable. However, switching power supplies at frequencies of the order of 40 or 80 or even 160 megahertz becomes difficult. By modifying the coding of phases of the power supply to be switched so that the number of phases enabled is proportional to the desired power supply output voltage rather than the length of a pulse in a time domain on any particular phase being proportional to the output voltage, dramatic improvements are achieved in switching losses, balance between phases and accurate tracking of the input signal. Rotation of switching across the phases achieves good balance and by jittering or randomizing the rotation, switching noise may be moved out of band.

Methods and apparatus for controlling the output voltage of a switched-mode power supply

A power efficient system and method for linear signal power amplification are provided. A linear power amplifier provides signal amplification from a system input to a system output and is drain-modulated with a power supply signal. An active compensation circuit generates the power supply signal, which is substantially proportional to an envelope of the system input, and provides it to the power amplifier through a low-impedance output. The active compensation circuit reduces noise in the system output spectrum.

Linear power amplifier circuit with a modulated power supply signal

A modulated power supply comprises first and second coding units. The second coding unit is responsive to a feed-forward error signal representing the error between the coded output of the first coding unit and an input modulating signal. The second coding unit codes for the more limited range of the error signal, thereby improving resolution. The first coding unit can comprise M coding units arranged in parallel with one another. The M coding units are operated in a manner which increases the apparent number of quantisation levels. This is achieved by feeding a modified version of the input modulating signal to each of the M coding units or by offsetting by quantisation grids of the M coding units. The improvements are particularly useful for improving performance where the input modulating signal has a wide bandwidth.

Modulated power supply

A cellular radio communication system for transmitting blocks of data over transmission links in which the quality of the transmission links are monitored. The system comprises a data storage means for storing sets of modulation scheme and forward error correction coding level pairs to give an optimum data rate at a predetermined bit error rate and a predetermined symbol rate for different quality transmission links. The database is interrogated and a modulation scheme and forward error correction coding level pair is allocated and applied to the blocks of data transmitted over a transmission link dependent on the monitored quality of the transmission link.

Cellular radio communications system

A modulated power supply comprises a converter having a primary power switching device and a secondary power switching device. The outputs of the primary and secondary power switching devices are combined to provide an output. A controller controls operation of the switching devices in response to a modulating input signal. Only the primary power switching device is operated while a property of the input signal lies within a first predetermined range and both the primary and the secondary power switching devices are operated while the property of the input signal lies outside the first predetermined range. This can reduce switching losses in comparison to operating the full array of switches. This is particularly well-suited to peaky signals. The property of the modulating input signal which causes the controller to bring secondary power switching devices into operation can be amplitude or rate of change of amplitude.

This invention relates to power detectors as employed in electrical circuits in general. The invention also relates to power detectors associated with high power amplifiers and, in particular, but not exclusively, relates to power detectors associated with telecommunications high power and high frequency power amplifiers. The present invention further provides apparatus and methods of switching amplifier blocks. The present invention seeks to provide an improved power detector having an increased range. In accordance with a first aspect of the invention, there is provided a radio frequency power detector, which detector comprises a radio frequency coupler, a radio frequency to direct current voltage converter and an operational amplifier circuit to provide voltage scaling; wherein the operational amplifier circuit includes a plurality of amplifiers operable to amplify the dc signals. The amplifiers can be switched into operation under microprocessor control or by diode switching. In accordance with a second aspect of the invention, there is provided a method of operating this radio frequency power detector.

Extended range power detector

This invention relates to an amplifier having digital micro-processor control apparatus and, in particular, to a high frequency power amplifier that includes a micro-processor control system to accurately regulate the operating point of the various amplifying elements in the high frequency power amplifier. The basic amplifier circuitry consists of a micro-controller, a variable voltage attenuator (VVA), a digital to analogue converter and an EEPROM. The EEPROM provides a lookup table which is read by the micro-controller, which then writes to the digital to analogue converter to set the control voltage to the variable voltage attenuator.

Growing community of inventors

Saffron Walden, United Kingdom

Graham Dolman