Abstract: A highly efficient power supply, a method for supplying power, and a method for arranging a power supply, for a UHF or microwave radio frequency amplifier intended for operation with a signal that has a power level which varies at a high frequency rate. The power supply has an output for connecting to a power supply input of the radio frequency power amplifier and includes a high rate controllable voltage supply employing electronic linear devices connected to the output, an element for quantifying power dissipated by the electronic linear devices and a low rate controllable current supply connected to the output. Preferably, the current supply is a substantially constant current supply at the frequency of the radio frequency signal. Preferably, the controllable voltage supply has a control input and is arranged to be controlled for outputting a voltage that is a function of the high frequency power variation.

Abstract: A method and system for quadrature modulation and digital-to-analog conversion of a sampled and digitally represented complex baseband signal which permits the use of simple, power-saving, accurate and effective digital signal processing up to a very high intermediate frequency. The invention requires an input signal in the form of an oversampled complex baseband signal. The inphase (I) and quadrature-phase (Q) components of this signal are first quantized to preferably 1 bit per sample, e.g., with the aid of &Sgr;&Dgr; modulation, so that the quantization noise is essentially forced outside the frequency band of the working signal. Then the sampling rate of the quantized versions of I and Q is converted to four times the desired carrier frequency, before the signal is quadrature modulated with a signal frequency exactly equal to one quarter of the final sampling rate.

Abstract: A system and method for simultaneous transmission and receival where the received signal is downconverted in a downconverting unit by using a portion of the transmitted modulated signal as LO for the downconversion. The downconversion is performed to an intermediate frequency signal having a frequency equal to the difference between the frequency of the transmitted signal and the frequency of the received signal. There is provided a common antenna for transmitting and receiving, and a duplex filter in front of the antenna to separate the transmitted signal and the received signal with the transmitter data on the transmitter side having been applied to a modulator. In front of the duplex filter on the transmitter side is provided a power amplifier. On the receiver side there is, in addition, provided a demodulator to permit withdrawal of user data for the user on the receiver side.

Abstract: There is described a system and a process for reducing leakage of LO (LLO) in a system which converts the frequency of a first signal by mixing the first signal with a second supplied signal to a third signal having a frequency which is different from the frequency for the first and second signal, where the first signal is divided via a number of couplers into four part-signals which are phase-shifted relative to each other, and that each such part-signal is led through its respective transistor there being added via each transistor a second signal which is mixed with the first signal, and that the signals which pass through the transistors are modulated by a number of regulating means for each transistor, preferably one or two per transistor, and that the frequency-shifted part-signals are added to a third signal via a number of couplings after having been phase-shifted, the voltage regulators being adjustable so that the signals are modulated and LLO is reduced.