Abstract: A radio transmitter and/or receiver comprising: an oscillator tuning circuit comprising an adjustable capacitor whose capacitance is adjustable by means of a first tuning signal; a filter tuning circuit comprising an adjustable capacitor whose capacitance is adjustable by means of a second tuning signal; an oscillator whose operational frequency is dependant on the reactance of the oscillator tuning circuit; a filter for filtering signals in the course of transmission and/or reception, and whose response is dependant on the reactance of the filter tuning circuit; and a tuning unit for generating the first and second tuning signals; wherein at least a part of the filter tuning circuit is a replica of at least a part of the oscillator tuning circuit and the tuning circuit is capable of generating one of the first and second tuning signals in dependence on the other of the tuning signals.

Abstract: The present invention is directed to a phase shifting arrangement for generating a set of mutually orthogonal signals. In one aspect, the invention provides a system that includes a phase shifting unit for receiving an input signal. The phase shifting unit includes a first phase shift circuit for generating a first output signal phase-shifted by a first amount with respect to the input signal, a second phase shift circuit for generating a second output signal phase-shifted by a second amount with respect to the input signal, and a third phase shift circuit for generating a third output signal phase-shifted by a third amount with respect to the input signal.