Telefonaktiebolaget Lm Ericsson (publ)

St-ericsson Sa

Carl Bryant

Henrik Sjöland

Jonas Lindstrand

Henrik SJÖLAND

A transceiver front-end for a communication device is connectable at a signal transmission and reception arrangement node to a signal transmission and reception arrangement adapted to transmit a transmit signal having a transmit frequency and to receive a receive signal having a receive frequency. The transceiver front-end is also connectable at a transmitter node to a transmitter adapted to produce the transmit signal and at a receiver node to a receiver adapted to process the receive signal. The transceiver front-end comprises a transformer, wherein the transmitter node is connected to a first node of a first side of the transformer, the receiver node is connected to a first node of a second side of the transformer, and the signal transmission and reception arrangement node is connected to a second node of the first side of the transformer and to a second node of the second side of the transformer. The transceiver front-end also comprises a first tunable capacitance connected between the transmitter node and the receiver node, and a second tunable capacitance connected between the signal transmission and reception arrangement node and a signal reference level. Corresponding transceiver, communication device and method are also disclosed.

Transceiver front-end

A power amplifier circuit utilizes a cross-coupled tapped cascade topology together with a technique of applying an RF injection current into a wideband node to provide a single-stage power amplifier with improved PAE, output power, and gain over a wide RF band. The amplifier circuit comprises a cross-coupled cascade transistor unit comprising a pair of cross-coupled cascode transistors, a cross-coupled switching transistor unit comprising a pair of cross-coupled switching transistors, and an RF current generator. RF current generator generates a differential RF injection current, while switching transistor unit amplifies the injection current to generate an amplified injection current at the wideband node of the amplifier circuit and the cascode transistor unit further amplifies the injection current to generate the desired amplified signal at the output of the amplifier circuit. The output signal amplitude generally depends on the differential injection current and the supply voltage Vapplied to the power amplifier circuit.

High efficiency power amplifier

Switched-mode amplifiers and devices having such amplifiers include quadrature pulse-width modulation that is based on cartesian (as opposed to polar) coordinates. Two sets of pulses that represent respective in-phase and quadrature components of a conventional cartesian-coordinates input signal can be combined such that the combined set of pulses can be provided to a switched-mode amplifier without nonlinear cartesian-to-polar transformation and its associated wider internal bandwidth and other problems.

Quadrature pulse-width modulation methods and apparatus

Instead of reducing the pulse widths of all pulses simultaneously in order to reduce the output power of a switched-mode amplifier linearized by a pulse-width modulator, the width of every other (or every n-th) pulse is reduced. When the widths of the selected pulses have been reduced to zero, the amplifier's output power can be further reduced by selecting further pulses from the remaining non-zero-width pulses, and reducing the widths of those pulses. For example, after every other pulse of an original output signal has been removed, every other pulse of the remaining pulses can be reduced to obtain still lower amplifier output power. In this way, the number of pulses (and thus the number of switching transitions) is reduced for small signals, and therefore the amplifier's switching losses are reduced and efficiency is improved.

Pulse-elimination pulse-width modulation

Otherwise conventional pulse-width modulators (PWMs) generate signals that can be converted into other forms by reshapers, and thereby overcome many of the problems of conventional PWMs in applications that demand high performance, such as switched-mode amplifiers and radio-frequency transmitters in modern communication systems. With a suitable reshaper, a conventional PWM differential signal can be converted into a signal more typical of linear amplification with nonlinear components (LINC) and still retain low-frequency information, such as the information needed for linearization of a switched-mode amplifier. Apparatus and methods of transforming signals are disclosed.

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Lund, Sweden

Carl Bryant