Dual-mode RF communication device
First Claim
1. A communication apparatus including a dual mode receiver, the receiver comprising:
- a narrowband signal mixer adapted to downconvert a narrowband radio frequency (RF) signal to a narrowband intermediate frequency (IF) signal (the narrowband IF signal having a narrowband IF signal carrier component, a first IF noise component having frequencies outside the narrowband IF carrier component, and a second IF noise component also having frequencies outside the narrowband IF carrier component) such that the narrowband IF carrier component lies within but near a limit of a predetermined range of signal frequencies;
a bandpass filter connected to said narrowband signal mixer, said bandpass filter adapted to allow signals within the predetermined range to pass through such that, when the narrowband IF signal is introduced, the first IF noise component is filtered out while the narrowband IF carrier component and the second IF noise component passes through; and
a dual-mode image-reject mixer (DMIRM) connected to said bandpass filter, said DMIRM adapted to attenuate the second IF noise component.
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Accused Products
Abstract
A novel RF to IF converter operates in two modes allowing both wide bandwidth signals and narrow bandwidth signals to be processed using the same wide bandwidth bandpass filter as well as a dual-mode image-reject mixer. As a mobile receiver, both wide bandwidth WCDMA or IMT-2000 signals and narrow bandwidth GSM signals pass through the same wide bandwidth channel select filter. In the GSM mode, signals lying to one side of the frequency range of the narrow GSM signal are attenuated by the wide bandwidth channel select filter. Then signals lying to the other side of the GSM signal are attenuated by an image-reject mixer. The image-reject mixer also downconverts the GSM signal. In the WCDMA or IMT-2000 mode, the wide bandwidth channel select filter attenuates signals outside of the WCDMA or IMT-2000 channel bandwidth, and the image-reject mixer downconverts the wide bandwidth signal without rejecting signals.
81 Citations
14 Claims
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1. A communication apparatus including a dual mode receiver, the receiver comprising:
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a narrowband signal mixer adapted to downconvert a narrowband radio frequency (RF) signal to a narrowband intermediate frequency (IF) signal (the narrowband IF signal having a narrowband IF signal carrier component, a first IF noise component having frequencies outside the narrowband IF carrier component, and a second IF noise component also having frequencies outside the narrowband IF carrier component) such that the narrowband IF carrier component lies within but near a limit of a predetermined range of signal frequencies;
a bandpass filter connected to said narrowband signal mixer, said bandpass filter adapted to allow signals within the predetermined range to pass through such that, when the narrowband IF signal is introduced, the first IF noise component is filtered out while the narrowband IF carrier component and the second IF noise component passes through; and
a dual-mode image-reject mixer (DMIRM) connected to said bandpass filter, said DMIRM adapted to attenuate the second IF noise component. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of processing radio frequency (RF) signal for communication, the method comprising:
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downconverting a narrowband radio frequency (RF) signal to a narrowband intermediate frequency (IF) signal (the narrowband IF signal having a narrowband IF carrier component, a first IF noise component having frequencies outside the narrowband IF carrier component, and a second IF noise component also having frequencies outside the narrowband IF carrier component) such that the narrowband IF carrier component lies within but near a limit of a predetermined range of signal frequencies;
filtering the first IF noise component while allowing the narrowband IF carrier component and portions of the second IF noise component to pass through; and
attenuating the second IF noise component. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification