Patent ID: 6621879
Filing Date: 2003-09-16
Classification: H03D

Abstract:
A digital radio system comprising a digital radio device which comprises an analog receiving part for receiving angle modulated radio frequency signals, which receiving part is coupled to frequency down conversion means for obtaining an intermediate frequency signal from the radio frequency signal, the digital radio device further comprising a quadrature demodulator for demodulating the intermediate frequency signal, the quadrature demodulator having a first branch, a phase shifting network in a quadrature branch, and a multiplier means, said first branch and said phase shifting network being coupled to said multiplier means, and wherein said phase shifting network comprises a series arrangement of a first resistor and a first capacitor, said series arrangement being coupled to a first inductor, a junction of the series arrangement and the first inductor being an output of the phase shifting network providing a quadrature signal and wherein said junction is directly connected to an input of said multiplier means, whereby the first resistor provides a damping such that an overall quality factor of the phase shifting network is substantially smaller than a quality factor of the inductor.