Lucent Technologies Inc.

Avaya Technology LLC

Boris Aleiner

Winston Hong Lieu

Boris A Bark

Joseph Aboukhalil

Joseph C Aboukhalil

A apparatus linearizing and technique for linearizing a non-linear power amplifier used in a transmitter of, e.g., a TDMA mobile wireless telephone. Linearization of the non-linear amplifier by changing the shape of the input signal is performed when the input signal level is high, thus increasing efficiency or reducing power consumption at that time, albeit at the cost of increased inter-symbol interference (ISI). However, since the input signals at that time are at a high level, the increased ISI can be tolerated and adjacent symbols can still be distinguished from one another. The invention allows use of a non-linear power amplifier which typically enjoys a lower current consumption than that of a linear power amplifier, thus increasing the time between battery recharges and/or reducing the overall size of the wireless telephone device. The power amplifier is operated in a linear mode when transmitted power is low, thus allowing differentiation between adjacent symbols (i.e., improvement of ISI). At high input power, the power amplifier is used in its non-linear mode to reduce current consumption. The signal shape is changed by changing the parameters of the root raised cosine filters. When the input level is low, the existing, otherwise conventional filter's parameters are used. However, when the input power level is high, modified parameters are used. Switching between the two sets of filter parameters is preferably performed at baseband. Thus, a relationship between RRCF filter parameters and the amount of spectrum utilized by the transmitted signal is utilized, and RRCF filter parameters are adjusted based on a desired limitation to an output spectrum.

Linearization of power amplifier

A power level determination device provides an output voltage usable as a specific reference power level corresponding to each RF input power level. The device includes a peak detector, which detects a pulse-type signal at its input and provides a non-pulse-type signal at its output. N comparators are provided, where N is an integer. Each of the N comparators has an output, a first input coupled to the output of the peak detector, and a second input coupled to a respectively different threshold voltage. The first one of the N comparators has a maximum threshold voltage. The threshold voltages decrease monotonically from No. 1 to No. N. N exclusive-OR components are provided. A first one of the N exclusive-OR components is coupled to ground and to the output of a first one of the N comparators. Each of the remaining N&minus;1 exclusive-OR components is coupled to the outputs of a respectively different pair of the N comparators, so that at any given time, a single one of the N exclusive-OR components has an output signal of a logic level that is different from the logic level of the outputs of the remaining N&minus;1 exclusive-OR components. N resistive divider circuits are coupled to respective ones of the N exclusive-OR components. Each of the N resistive divider circuits provides a respectively different predetermined output voltage as an indication of a power level of the pulse-type signal, if the exclusive-OR component to which that circuit is coupled is the single one of the N exclusive-OR components.

Power level determination device in an RF booster for wireless communications

A booster for amplifying the signal of a mobile unit of a cellular telephone system. The booster includes a level determination device which produces a reference level based on a power level of a signal received from the mobile unit. The level determination device includes a step voltage circuit which produces a step voltage based on the power level of the signal received from the mobile unit. The step voltage is supplied to a resulting voltage circuit which produces a resulting voltage based on the step voltage, the resulting voltage suitably providing a reference level for the booster.

Methods and apparatus for determination of a power level in an RF booster for wireless communications

In a wireless communications system, an RF booster provided intermediate an antenna device for receiving RF signals and a receiver device for providing a predetermined amount of gain to said received RF signals and converting said RF signals to audio frequency signals, the RF booster comprising a first amplifier device for receiving input signals from the antenna via a first cable connecting device, the first low noise amplifier providing a first gain equal to the predetermined amount of gain of the receiver device; a second amplifier device connected in series with the first amplifier device, the second amplifier device connected via a second cable connecting device to the receiver device and providing a second amount of gain of a value sufficient to compensate for signal loss provided by the first and second cable means; and a switch element capable of switching out the first gain of the first amplifier device, the switch element controlled by a control signal in accordance with a sensed level of received input RF signals, wherein for small input RF signals received, the switch element is switched off to provide both the first and second gain in the RF booster, and for large input signals received, the switch element is switched on to provide only the second gain for the RF booster.

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Somerset, NJ, United States of America

Boris Aleiner