Multi-level mixer architecture for direct conversion of FSK signals
First Claim
Patent Images
1. A receiver comprising:
- a first I/Q downconverter to generate a first set of I and Q channels at a first IF;
a second I/Q downconverter coupled to the first I/Q downconverter to generate a second set of I and Q channels at a second IF in response to the I channel of the first set of I and Q channels and to generate a third set of I and Q channels at a second IF in response to the Q channel of the first set of I and Q channels; and
an image rejection stage coupled to outputs of the second I/O downconverter to cancel an image frequency due to a downconversion performed by the first I/Q downconverter.
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Abstract
A multi-level quadrature (I/Q) mixer for use in a communication system such as a paging device, where the mixer includes first and second I/Q downconversions followed by demodulation. The first I/Q downconversion converts an I/Q signal pair to a first IF, and the second I/Q downconversion converts an I/Q signal pair to a second IF. The first IF may or may not be the center frequency depending on the number of subchannels in the single channel being downconverted.
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Citations
20 Claims
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1. A receiver comprising:
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a first I/Q downconverter to generate a first set of I and Q channels at a first IF; a second I/Q downconverter coupled to the first I/Q downconverter to generate a second set of I and Q channels at a second IF in response to the I channel of the first set of I and Q channels and to generate a third set of I and Q channels at a second IF in response to the Q channel of the first set of I and Q channels; and an image rejection stage coupled to outputs of the second I/O downconverter to cancel an image frequency due to a downconversion performed by the first I/Q downconverter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for demodulating a multi-carrier QFSK signal that includes an I signal and a Q signal, both said I and Q signals having signals of first and second frequency included therein, said apparatus comprising a multi-level mixer for separating the signals of the first and second frequencies into multiple subchannels simultaneously using parallel levels of mixing and demodulation, wherein the parallel levels of mixing generate multiple pairs of I/Q signals, each pair representing an independent subchannel, and
wherein the multi-level mixer comprises a first I/Q downconverter to generate a first set of I and Q channels at a first IF; - and
a second I/Q downconverter coupled to the first I/Q downconversion to generate a second set of I and Q channels at a second IF in response to the I channel of the first set of I and Q channels and to generate a third set of I and Q channels at a second IF in response to the Q channel of the first set of I and Q channels; and an image rejection stage coupled to outputs of the second I/O downconverter to cancel an image frequency due to a downconversion performed by the first I/O downconverter. - View Dependent Claims (17, 18, 19, 20)
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Specification