| 摘要 |
A noise isolation passive mixing apparatus is designed to mitigate noise contribution from intermediate frequency (IF) filters and amplifiers in a radio frequency translation stage. Common-gate configuration devices are inserted between passive mixer output and input of a transimpedance amplifier. In this way, circulation of the input-referred noise of the transimpedance amplifier is decreased, because of the relatively high output impedance of the common-gate devices, and the noise figure of the mixing apparatus can be improved. Since the radio frequency signal still sees low impedance, a radio frequency transconductance (RF gm) stage can be removed from the mixing apparatus, reducing current consumption. A double-balanced mixing apparatus with this general architecture may be implemented in a 0.18 micrometer CMOS technology and used in a low-IF global positioning system operating at 1.575 GHz, in an access terminal of a cellular communication system, and in other systems.
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