| 摘要 |
A flexible and programmable circuit for generating a radio frequency signal for transmission includes two delta-sigma modulators (62,64), a quadrature clock generator (70) for generating two clock signals (71, 73) having a 90 degree phase difference, two commutators (66, 68) for multiplying the two modulator outputs by +1 and -1 on alternating half cycles of the two quadrature clock signals respectively, a summer (80) for summing the two commutated outputs, and a filter (82) for removing unwanted frequency components before transmission. The circuit directly generates a radio frequency signal without the need for additional frequency translation after the commutation stage.
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