Abstract: An active cancellation unit is disclosed for improving the noise cancellation between a transmitter and a receiver which are connected to an antenna using a duplexer, the unit comprising a coupler sampling a signal to transmit provided by the transmitter, a cancellation duplexer having characteristics similar to the duplexer and receiving the sampled signal to provide a simulated signal and an active component receiving the simulated signal and providing an amplified signal having a phase 180 degree shifted with respect to the simulated signal; and a coupler for injecting the simulated signal at the receiver.

Abstract: A method and apparatus for amplifying a signal modulated in amplitude using amplifiers having a given dynamic range corresponding to a limited conduction angle, comprising separating the signal in a first signal and in a second signal depending on the dynamic range of the amplifiers, wherein each of the first signal and the second signal has a corresponding phase assigned based on an amplitude of the signal, amplifying each of the first signal and the second signal using the amplifiers and combining the amplified signals.

Abstract: A duplexer for a communication device having a transmission unit, a reception unit and a shared antenna is disclosed. The duplexer comprises a first signal path between the transmission unit and the reception unit, the first signal path comprises a filter unit filtering the reception signal, the filtering unit provides a filtered signal to the reception unit. The duplexer further comprises a second signal path between the transmission unit and the reception unit. The second signal path comprises a cancellation unit which receives a sample of the transmission signal and produces a compensation signal. The injection of the compensation signal to the first signal path reduces the leakage signal, thereby producing a substantially leakage-free reception signal.

Abstract: A method and apparatus for amplifying a signal modulated in amplitude using amplifiers having a given dynamic range corresponding to a limited conduction angle, comprising separating the signal in a first signal and in a second signal depending on the dynamic range of the amplifiers, wherein each of the first signal and the second signal has a corresponding phase assigned based on an amplitude of the signal, amplifying each of the first signal and the second signal using the amplifiers and combining the amplified signals.

Abstract: A duplexer for a communication device having a transmission unit, a reception unit and a shared antenna. The shared antenna transmits a portion of a transmission signal provided by the transmission unit and receiving a reception signal. The duplexer generates a leakage signal from the transmission unit toward the reception unit. The leakage signal being added to the reception signal. The duplexer comprises a first signal path between the transmission unit and the reception unit. The first signal path comprises a filter unit filtering the reception signal. The filtering unit provides a filtered signal to the reception unit. The duplexer further comprises a second signal path between the transmission unit and the reception unit. The second signal path comprises a cancellation unit which receives a sample of the transmission signal and produces a compensation signal.

Abstract: In a feedforward amplifier for amplifying an input signal in order to produce an amplified output signal, an error signal representative of distortion in the amplified output signal is produced and an adaptive linearization circuit is provided. In this adaptive linearization circuit, serially interconnected attenuator, phase shifter and error amplifier process the error signal to produce a feature-adjusted error signal. A coupling member combines the feature-adjusted error signal in the amplified output signal in order to cancel distortion in this amplified output signal, and a comparator/controller circuit is responsive to the error signal and the feature-adjusted error signal to control the attenuator and the phase shifter.

Abstract: A linearizer channel amplifier for use in conjunction with a power amplifier comprises an input series circuit formed of a first variable attenuator, an input drive amplifier and a power limiter, and an output series circuit formed of a second variable attenuator and an output drive amplifier. Between the input and output series circuits is interposed a linearizer. In this linearizer, a splitter produces first and second signal portions, a first path comprises serially interconnected predistorter and third variable attenuator for distorting and adjusting the amplitude of the first signal portion, a second path comprises serially interconnected phase shifter and fourth variable attenuator for phase-shifting and adjusting the amplitude of the second signal portion, and a combiner combines the distorted and amplitude-adjusted first signal portion and the phase-shifted and amplitude-adjusted second signal portion to form a predistorted output signal applied to the output series circuit.