The AR8035-AL1B is a Gigabit Ethernet PHY transceiver from Qualcomm Atheros in QFN-32 (5x5mm). It implements IEEE 802.3 Gigabit Ethernet physical layer with RGMII (Reduced Gigabit Media Independent Interface) or SGMII (Serial Gigabit MII) MAC connection. The transmitter takes 4-bit parallel data from RGMII at 125MHz, performs 8B/10B encoding, scrambles the data, and drives the differential PAM5 (5-level Pulse Amplitude Modulation) signal on all four MDI pairs (TXP/TXN) at 125Mbaud per pair, achieving 1000Mbps. For 10/100Mbps, the PHY reverts to MLT-3 or 4B/5B encoding on 2 pairs. Auto-negotiation (IEEE 802.3ab) advertises 10/100/1000 capability and selects the highest common speed. The receiver includes a DSP-based equalizer that compensates for up to 100m of Cat5e/6 cable attenuation. The -AL1B revision supports IEEE 802.3az Energy Efficient Ethernet (EEE), reducing power by 60% during idle periods by entering low-power idle (LPI) mode. The MIIM interface provides register access for configuration, status monitoring, and cable diagnostics (TDR-based). The 125MHz reference clock can be generated internally or supplied externally.