1. Technical Field
The present invention generally relates to signal processing for the reception of radio signals, especially by wide-band receivers.
It finds applications, in particular, in radio-frequency receiver, e.g., Software Defined Radio receiver, in cellular phones and other mobile communication devices.
2. Related Art
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Software Defined Radio (SDR) aims the capability of supporting multiple radio standards and bands. For example, SDR are adapted to receive radio frequency signals in a plurality of frequency ranges. To this end, they are usually built with a wide-band Low Noise Amplifier (LNA) followed by a configurable base-band filter, and an analogical-to-digital converter. Nevertheless, constraints are very high and Surface Acoustic Wave (SAW) filters are usually inserted between the antenna input and the receiver input to attenuate interferers in the received signal.
However, using SAW filters cancels all benefits of a wide-band receiver design. Indeed, the LNA can no longer be shared among different frequency ranges because of the SAW filter included between the LNA and the antenna, which filters the received signal in a unique narrow band and which is not reconfigurable. To obtain a wide-band receiver, it is then necessary to have such a receiver, or at least a part of it, for each of the radio frequency ranges, instead of having a unique receiver for a plurality of frequency ranges. Furthermore, SAW filters add extra components, board area and degrade the receiver sensitivity by 2 to 3 dB.