Ethernet transceiver with PHY-level signal-loss detector
An Ethernet transceiver includes physical-layer (PHY) circuitry and a signal-loss detector. The PHY circuitry is configured to receive a signal from a peer transceiver, to process the received signal in a series of digital PHY-level processing operations, and to output the processed signal for Medium Access Control (MAC) processing. The signal-loss detector is configured to receive, from the PHY circuitry, a digital version of the received signal, and to detect a signal-loss event based on an amplitude of the digital version of the received signal.
1. An Ethernet transceiver, comprising:
physical-layer (PHY) circuitry, configured to receive a signal from a peer transceiver, to process the received signal in a series of digital PHY-level processing operations, the PHY-level operations comprising at least cancellation of echo signals in the received signal followed by equalization of the received signal, the PHY circuitry further configured to output the processed signal for Medium Access Control (MAC) processing; and
a signal-loss detector, configured to receive, from the PHY circuitry, a digital version of the received signal, wherein the echo signals in the digital version have been canceled but the digital version is not equalized, and to detect a signal-loss event based on an amplitude of the digital version of the received signal.
2. The transceiver according to claim 1 , wherein the signal-loss detector is configured to receive from the PHY circuitry a digital version of the received signal that underwent only an initial subset of the PHY-level processing operations.
3. The transceiver according to claim 1 , wherein the signal-loss detector is configured to detect the signal-loss event before an error event, caused by the signal-loss event, is identified in the MAC processing.
4. The transceiver according to claim 1 , wherein the signal-loss detector is configured to calculate an average amplitude of the digital version of the received signal, and to detect the signal-loss event by identifying that the average amplitude is below a predefined amplitude threshold.
5. The transceiver according to claim 1 , wherein, in response to detecting the signal-loss event, the signal-loss detector is configured to initiate a reset operation to reset the transceiver.
6. The transceiver according to claim 1 , wherein the PHY circuitry is configured to process the received signal in accordance with a PHY-control state-machine having multiple states indicative of a current state of a link between the transceiver and the peer transceiver, and wherein the signal-loss detector is configured to output a notification of the signal-loss event only in a predefined partial subset of the states.
7. The transceiver according to claim 1 , wherein the signal-loss detector is configured to detect the signal-loss event only after the received signal is initially detected by the PHY circuitry.
8. A method for signal-loss detection in an Ethernet transceiver, the method comprising:
using physical-layer (PHY) circuitry:
receiving a signal from a peer transceiver;
processing the received signal in a series of digital PHY-level processing operations, the PHY-level operations comprising at least cancellation of echo signals in the received signal followed by equalization of the received signal; and
outputting the processed signal for Medium Access Control (MAC) processing; and
receiving, from the PHY circuitry, a digital version of the received signal, wherein the echo signals in the digital version have been canceled but the digital version is not equalized, and detecting a signal-loss event based on an amplitude of the digital version of the received signal.
9. The method according to claim 8 , wherein receiving the digital version comprises receiving from the PHY circuitry a digital version of the received signal that underwent only an initial subset of the PHY-level processing operations.
10. The method according to claim 8 , wherein the detecting the signal-loss event is performed before an error event, caused by the signal-loss event, is identified in the MAC processing.
11. The method according to claim 8 , wherein detecting the signal-loss event comprises calculating an average amplitude of the digital version of the received signal, and identifying that the average amplitude is below a predefined amplitude threshold.
12. The method according to claim 8 , further comprising, in response to detecting the signal-loss event, initiating a reset operation to reset the transceiver.
13. The method according to claim 8 , wherein processing the received signal comprises applying a PHY-control state-machine having multiple states indicative of a current state of a link between the transceiver and the peer transceiver, and wherein detecting the signal-loss event comprises outputting a notification of the signal-loss event only in a predefined partial subset of the states.
14. The method according to claim 8 , wherein detecting the signal-loss event is performed only after the received signal is initially detected by the PHY circuitry.