温度变化：多千兆汽车以太网链路稳定性中未被重视的环境因素.pdf

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1、Temperature VariationThe Unappreciated Environmental Factor in the Stability of Multigigabit Automotive EthernetAlireza Razavi,Ragnar Jonsson|MarvellIEEE SA Ethernet&IP Automotive Technology Day19-20 September 2023,So Paulo,Brazil 2023 Marvell.All rights reserved.2Vehicles operate in the extremes 20

2、23 Marvell confidential.All rights reserved.2 2023 Marvell.All rights reserved.3Two types of temperature tests“Error-free”links at any valid temperature“Error-free”as temperature ramps across rangeStatic testsRamp tests 2023 Marvell.All rights reserved.4Static testing process is well-definedPHY link

3、s without error at any valid temperatureThe underlying standard provides a limit on cable/board electrical characteristics For all temperatures,the cable/board should not violate these requirements on insertion loss,return loss,jitter,etc.Ramp testing is well-defined,too,but to get good resultshard

4、2023 Marvell.All rights reserved.5Whats so hard about passing a ramp test?2023 Marvell confidential.All rights reserved.5 2023 Marvell.All rights reserved.6First things first:measurement setup 15m shielded twisted pair with four inline connectors Temperature range:-40 to 105 Celsius15m cableDUTLKP 2

5、023 Marvell.All rights reserved.7Channel insertion loss increases with temperature Source:Marvell15m BASE-T1 cable 2023 Marvell.All rights reserved.8How do we address insertion loss variability?CoderEqualizer/coderAnalog to digital convertorDigital to analog convertorEcho cancelerTransmitbitsReceive

6、dbitsHybridLink partnerCableProblem:variability in cable insertion loss over temperatureOverdesign analog front-endand apply active gain controlApply fasteradaptive equalizationAddressing insertion loss variability increases chip size,power and cost 2023 Marvell.All rights reserved.9Cable delay vari