Lucent Technologies Inc.

Other

Huan-Shang Tsai

Young-Kai Chen

Jiunn-Tsair Chen

Sanjay Kasturia

Jenshan Lin

A circuit that increases the efficiency of a radio frequency mobile telephone unit is disclosed. When the signal strength between the base station and the mobile unit is below a predetermined signal strength level, the power amplifier is turned on and the transmitter circuit of the mobile unit fully amplifies the RF signal. However, when the signal strength between the mobile telephone unit and the base station is above a predetermined signal strength level, the power amplifier is deactivated and bypassed from the transmitter circuitry, thereby conserving the battery power of the mobile unit.

Method and apparatus for enhancing transmitter circuit efficiency of mobile radio units by selectable switching of power amplifier

A feedforward linearizer includes a signal cancellation circuit and an error cancellation circuit. The signal cancellation circuit includes a tap delay line, that delay the input signal by a predetermined time delay so as to provide several delayed versions of the input signal. Each delayed version of the input signal is weighted by a tap coefficient. The weighted signals are then added together and fed to the power amplifier. The tap coefficients are derived such that the signals traveling through the upper and lower branch of the signal cancellation loop are aligned and that the output signal of the power amplifier is equalized.

Adaptive joint linearization, equalization and delay alignment for a wideband power amplifier

A feedforward linearizer for amplifying an input signal comprises a signal cancellation circuit which has a first branch and a second branch. A first amplifier provided in the first branch receives the input signal intended to be amplified and generates an output signal received by a signal cancellation vector modulator. A signal cancellation adder receives the signal generated by the signal cancellation vector modulator and the input signal via the second branch and provides an error signal. The feedforward linearizer also comprises an error cancellation circuit that has a first branch and a second branch. An error cancellation adder in the first branch receives the output signal provided by the first amplifier and generates the output signal of the linearizer. An error cancellation vector modulator in the second branch receives an error signal provided by the signal cancellation adder and provides an error adjusted signal to a second auxiliary amplifier. The second auxiliary amplifier provides an input signal to the error cancellation adder. A digital signal processor provides a signal cancellation adjustment signal, .alpha., to the signal cancellation vector modulator and an error cancellation adjustment signal, .beta., to the error cancellation vector modulator respectively, such that the output signal of the signal cancellation adder is a signal that substantially represents the error components provided by the first amplifier, and the output signal of the error cancellation adder is an amplified version of the input signal, with substantially no internmodulation components.

Fast adaptive wideband power amplifier feed forward linearizer using a

A cellular communication signal receiver receives a desired signal in the presence of at least one co-channel interference signal. The receiver comprises a channel estimator configured to receive a plurality of training signal samples to estimate the finite impulse response to the desired signal and the co-channel interference signal. The finite impulse response estimates having a predetermined number of channel taps defining the length of the desired channel and the length of co-channel interference channel. A Viterbi decoder is coupled to the channel estimator, and configured to receive the desired and co-channel interference signals. The channel estimator generates channel tap estimates. A power calculator is coupled to the channel estimator and configured to estimate the power of the estimated channel taps. A joint channel trimmer is coupled to the power calculator and configured to maintain a joint channel length, such that the desired signal channel length plus the co-channel interference channel length have a fixed size that defines the number of states the Viterbi decoder allocates to the desired signal and the co-channel interference signal.

Joint maximum likelihood sequence estimator with dynamic channel

A feedforward linearizer for amplifying an input signal comprises a signal cancellation circuit which has a first branch and a second branch. A first amplifier provided in the first branch receives the input signal intended to be amplified and generates an output signal received by a signal cancellation vector modulator. A signal cancellation adder receives the signal generated by the signal cancellation vector modulator and the input signal via the second branch and provides an error signal. The feedforward linearizer also comprises an error cancellation circuit that has a first branch and a second branch. An error cancellation adder in the first branch receives the output signal provided by the first amplifier and generates the output signal of the linearizer. An error cancellation vector modulator in the second branch receives an error signal provided by the signal cancellation adder and provides an error adjusted signal to a second auxiliary amplifier. The second auxiliary amplifier provides an input signal to the error cancellation adder. A digital signal processor, comprising a signal processing circuit, provides a signal cancellation adjustment signal, .alpha., to the signal cancellation vector modulator and an error cancellation adjustment signal, .beta., to the error cancellation vector modulator, such that the output signal of the signal cancellation adder is a signal that substantially represents the error components provided by the first amplifier, and the output signal of the error cancellation adder is an amplified version of the input signal, with substantially no intermodulation components.

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Parsippany, NJ, United States of America

Huan-Shang Tsai