| 摘要 |
PROBLEM TO BE SOLVED: To surely perform DC offset cancellation without extending a time required for a DC offset cancellation operation in a direct conversion type receiving circuit. SOLUTION: The receiving circuit includes an LNA 3 for differentially amplifying a received signal; a local circuit 17 for generating a first local oscillation signal; a mixer 4 for performing frequency conversion of the reception signal into a baseband signal by mixing the differentially amplified reception signal with the first local oscillation signal; LPFs 7, 9 and 11 and GCAs 8, 10 and 12 which perform differential operations respectively and are subjected to multi-stage connection; and an RFIC controller 19. The RFIC controller 19 stops frequency conversion of the reception signal into the baseband signal by controlling the local circuit 17 during a DC offset cancellation operation of the GCAs 8 and 10, and performs frequency conversion of the reception signal into the baseband signal by controlling the local circuit 17 during a DC offset cancellation operation of the GCA 12. COPYRIGHT: (C)2009,JPO&INPIT
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