PHY包括MII/GMII(介質獨立接口)子層,PCS(物理編碼子層),PMA(物理介質附加)子層,PMD(物理介質相關)子層,MDI子層。

• MII：medium independent interface，介質無關接口。提供公共接口，屏蔽這些物理層的不同細節

• PCS：physical coding sublayer，物理編碼子層，8B10B編碼或8B1Q4編碼等。

• PMA: Physical?Medium?Attachment?sublayer，物理介質連接子層，負責數據串化/解串化以及數據-碼元映射（4D-PAM5等）。

• PMD：Physical?Medium?Dependent?sublayer，物理介質相關子層，信號轉換到特定物理介質上或反向轉換。

• MDI：Medium Dependent Interface,媒介相關接口，PMD層和物理媒質的接口，是串行比特的物理接口，接到RJ45

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1. PCS

? Responsible for encoding/decoding?data

? Input to Carrier Sense and Collision?Detect block, if used by the protocol

? Serializing/deserializing code groups?at PMA interface

? Important for loopback testing

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2. PMA

? Maps transmit and receive code-bits?between the PCS and PMD, if present?

?? ?– Otherwise, directly maps code-bits to?signal values used for the particular?network implementation

? ? bit to data symbol mapping, and data symbol to bit mapping

? Recovers clock from received signal

? Generates indications and carrier errors?from the PMD (if present) and sensing?receive channel failures (Used for?debugging)

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3. PMD

? Maps TX and RX symbol streams to signal values appropriate to?medium used

? The PMD may not always be part of the PHY?

?? ?– Use of the PMD is defined by the specific version of the standard?implemented by the PHY

? Provides inputs to line drivers, and accepts input from line receivers

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The1000BASE-T1 PMD defines the transmit and receive electrical characteristics. The PMD also specifies the minimum link segment characteristics, EMC requirements, and test modes.

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4.?realtek?PHY

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