| 摘要 |
In various embodiments, a system and method for improving a noise figure (NF) of a time division duplex (TDD) communications system includes a pre-amplified antenna unit having a plurality of antennas and associated low-noise amplifiers (LNA). Each of the associated LNA's is arranged to receive signals from a phase-matched pair of antennas selected from the plurality of antennas. For each of the phase-matched antenna pairs, a variable negative gain circuit may be coupled to a TDD signal output of the associated LNA such that a remote radio head (RRH) may be suitably coupled to an output of the variable gain circuit. The variable gain circuit is configured to provide a negative gain to the TDD signal appropriate to ensure that a dynamic range of the RRH is not reduced from a desired dynamic range due to excess gain provided by the LNA. A method of retrofitting a conventional pre-amplified antenna unit includes inserting a variable negative gain circuit so that the modified pre-amplified antenna may be used with any vendor's RRH.
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