Abstract: A method and a device for tuning power amplifier (PA, 203) properties such as back-off. A peak-to-average value (PAR) of the amplifier input signal is first obtained by control means (206) and then used for adjusting the power amplifier (203) with tuning means (204, 208, 210) functionally connected to the amplifier (203). The suggested solution is advantageously exploited in a wireless communications device like a mobile terminal to optimize the performance thereof by, for example, reducing the power dissipation in the transmitter.

Abstract: A RF transmitter has at least one amplifier having an input terminal for receiving a phase modulated signal to be transmitted on an RF carrier and an input node for receiving a modulation signal for amplitude modulating the RF carrier. The RF transmitter further includes an amplitude modulator having an output coupled to the input node of the power amplifier through a low-pass filter. The low-pass filter includes at least one variable filter component for varying a bandwidth of the low-pass filter. In a preferred embodiment an envelope elimination and restoration (EER) RF transmitter includes at least one power RF amplifier having the input terminal for receiving the phase modulated signal to be transmitted on the RF carrier, and further including an input power node for receiving a modulated voltage for amplitude modulating the RF carrier.

Abstract: The invention relates to a matching circuit for adapting an amplifier to load impedance at various output power levels of the amplifier, and a method for adapting the amplifier to load impedance at various output power levels of the amplifier. The matching circuit comprises an LC circuit, i.e. an electric circuit switching consisting of at least one coil and at least one capacitor for tuning harmonic signals resulting from amplifier non-linearities. At least one capacitor of the LC circuit (600, 602, 604, 606) is an adjustable microelectromechanical (MEMS) capacitor (602, 606). The LC circuit comprises an interface for receiving control signals (220) adjusting capacitance of the microelectromechanical (MEMS) capacitor. The control signals (220) adjust the capacitance of the microelectromechanical (MEMS) capacitor (602, 606) such that the LC circuit (600, 602, 604, 606) resonates at the frequency of the harmonic signal to be tuned.

Abstract: The course of an oscillating signal is controlled in mutually alternative first active component (31) and second active component (32), both of which can be set into active state by a certain first value of a control signal brought to the component and which are in inactive state with a certain second value of the control signal. The signal is directed to pass through the first active component (31) by setting it into active state by a control signal (33) brought to it. At the same time, the second active component (32) is prevented from affecting the course of the signal by setting a control signal brought to it to a second value (107, 111).

Abstract: A transmitter (2) for communication devices according to the invention comprises a high-frequency power amplifier for amplifying the high-frequency signal to be transmitted, which high-frequency power amplifier includes an output stage for giving an amplified high-frequency signal, and measuring devices for measuring the power (Pdc) of the high-frequency signal. The measuring devices comprise devices (A1, RECT1, INT1, A2, RECT2, INT2) for measuring the voltage (VCE) and current (IE) of the high-frequency signal in said output stage, and means (M1, INT3) for calculating the power of the high-frequency signal on the basis of the measured high-frequency voltage (Vmeas) and high-frequency current (Imeas). A mobile station (1) according to the invention has a transmitter (2) for transmitting signals, which transmitter (2) includes a high-frequency power amplifier for amplifying the high-frequency signal to be transmitted.