An amplifier arrangement comprising an amplifier for amplifying an input radio frequency (RF) signal to generate an output RF signal. A linear function processor generates a linear function correction signal which is a linear function of previous samples of the input signal in order to compensate for distortion effects of the amplifier related to the history of the input signal. A non-linear function processor generates a non-linear function of the input signal in order to compensate for instantaneous distortion effects of the amplifier. Then a pre-distortion processor distorts the current input signal in accordance with the linear and non-linear function correction signals in order to compensate for both types of distortion in the output signal.

A linear amplifier arrangement

Described is a communication system including mobile communication devices. In the described system, the mobile devices may be wrist-worn watches such as are in common use today, except that the watches are specially configured to receive data in a “broadcast” mode and transmit and/or receive data in a “localcast” mode. The localcast mode includes the ability to transmit and receive data in a peer-to-peer fashion, allowing mobile devices to communicate directly with each other. The ability to combine two of these communication modes in a small, integrated and hence inexpensive and low-power package provides many advantages over existing personal communication device solutions.

System and apparatus for performing broadcast and localcast communications

The present invention provides high power linear amplification of an amplitude and/or phase modulated signal using multiple saturated (or if desired, unsaturated) amplifiers (4) driven by an appropriate set of switched (5), and/or phase modulated (6) constant amplitude signals derived from the input signal. The present invention combines three amplitude reconstruction techniques and implements the amplitude reconstruction modulator (11) digitally.

Amplification using amplitude reconstruction of amplitude and/or angle modulated carrier

Frequency translation and applications of same are described herein, including wireless local area network (WLAN) applications such as IEEE Standard 802.11 WLANs. Such applications include, but are not limited to, frequency down-conversion, frequency up-conversion, enhanced signal reception, unified down-conversion and filtering, and combinations and applications of same.

Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation

A transceiver for transmitting and receiving signals includes a transmitter operative to up-convert baseband signals from a baseband frequency into RF signals at a radio frequency (RF) frequency and output the RF signals, a receiver operative to receive RF signals and down-convert the RF signals into baseband signals having the baseband frequency, and a plurality of calibration paths coupling the transmitter to the receiver. Any of the calibration paths can be selected to be active when calibrating components of the transceiver. Tunable components can use calibration information to optimize transceiver performance.

Direct-conversion transceiver enabling digital calibration

A linear transmitter (101) using predistortion includes a modulator (103), a predistorter (107), a digital quadrature modulator (111), an upconverter (113), a power amplifier (115), and an antenna (117). In addition, the transmitter (101) has a feedback loop including a coupler (119), a downconverter (123), a digital quadrature demodulator (125), and a trainer (131). The digital data to be transmitted is provided into the modulator (103), which converts the digital data into in-phase and quadrature component signals. The in-phase and quadrature component signals are then provided to the predistorter (107), which "predistorts" the component signals prior to amplification. The digital quadrature modulator (111) converts the component signals into a single analog signal. The upconverter (113) upconverts this signal from the predistorter (107) into the desired frequency of transmission, which is provided to the power amplifier (115) and the antenna (117) for amplification and broadcast. The coupler (119) provides a portion of the amplified signal to the analog downconverter (123), which lowers the frequency of this signal to a range that is easily processed. The signal is then provided to the digital quadrature demodulator (125), which outputs the in-phase and quadrature component signals of the signal. These in-phase and quadrature component signals are provided to the trainer (131) which analyzes them with the output signals from the modulator. The trainer (131) compares these signals and updates the predistorter (107) so that the digital quadrature demodulator (125) output signals are substantially equivalent to the modulator (103) output signals.

Linear transmitter using predistortion

A system for linearly transmitting an amplified output signal using predistortion whereby a straight/direct inverse modeling scheme (503) is used to determined the inverse of the distortion caused by a power amplifier (103). The predistorter system (407) stores complex coefficients in a LUT (603), which are then used as tap weights of a digital filter (601) implementing the predistorter. The predistortion is done by a non-linear filter (601) which incorporates both instantaneous and average envelope power or magnitude effects thereby compensating for modulation envelope memory effects of the power amplifier (103). The LUT (603) is addressed as a function of the instantaneous power or magnitude of the current sample and a profile of the power or magnitude envelope of previous samples. The LUT (603) is updated with values that are indexed as a function of the powers or magnitudes of past samples and the power or magnitude of the current sample.

Vladimir Pavlovic

Papers

Linear transmitter using predistortion

Method and apparatus for linear transmission by direct inverse modeling