IEEE RTPGE. Optimisation of physical layer components for RTPGE. Thomas Müller, Gunnar Armbrecht, Stephan Kunz (Rosenberger)

Transcription

1 Optimisation of physical layer components for RTPGE Thomas Müller, Gunnar Armbrecht, Stephan Kunz (Rosenberger) Supporters: Mehmet Tazebay (Broadcom) Thomas Suermann (NXP) Rosenberger Hochfrequenztechnik GmbH & Co. KG

2 Outline Channel definition MDI connector performance measurements Cable insertion loss over temperature EMC Evaluation of the influence of inline connectors on EMC by means of stripline VNA measurements Outlook on using system simulation for predicating stripline test results Thomas Müller (Rosenberger) 2

3 MDI connector performance DUT description Automotive twisted pair Ethernet connector Supports jacketed and unjacketed unshielded cables Electrically optimised for Impedance matched to 1 Ohm High balance Low crosstalk Minimum untwist area Open interface to the industry Thomas Müller (Rosenberger) 3

4 MDI connector performance VNA measurement setup Whole link consists of 2x breakout boards 2x MDI connectors 2 mm jacketed cable Plot against the following limits for unshielded Ethernet connectors: Cat 5 (IEC ) Cat 6a (ISO/IEC ) OPEN alliance spec draft v.3 Thomas Müller (Rosenberger) 4

5 Sdd11 [db] Sdd21 [db] MDI connector performance VNA measurements Return- and insertion-loss -1 Return loss [Pair 1] Insertion loss [Pair 1] * f [MHz] f [MHz] * Including breakout board Thomas Müller (Rosenberger) IEC 663 Cat. 5 IEC 663 Cat. 6a OPEN Alliance v.3

6 Scd11 [db] Scd21[dB] MDI connector performance VNA measurements - Balance TCL [Pair 1] f [MHz] TCTL [Pair 1] f [MHz] Thomas Müller (Rosenberger) IEC 663 Cat. 5 IEC 663 Cat. 6a OPEN Alliance v.3

7 Sdd21 (near-end) [db] Sdd21 (far-end)[db] MDI connector performance VNA measurements - Crosstalk NEXT [Pair 1 to Pair 2] f [MHz] FEXT [Pair 1 to Pair 2] f [MHz] Thomas Müller (Rosenberger) IEC 663 Cat. 5 IEC 663 Cat. 6a OPEN Alliance v.3

8 text textbox Impedance [ ] ( t rise = 7ps) MDI connector performance Differential impedance Comparison to standard contact Z x MDI connector 7 l = 3 mm untwist standard 6 l = 5 mm untwist contact l = 7 mm untwist Time [ns] 7 ps rise time 1 Ω ± 1 Ω (~ 5 MHz) Keeping the untwist length small is essential This is issue is not addressed by standard contacts (e.g. USCar). Z 9 8 df (u; v) Thomas y Müller (Rosenberger) 8

9 Cable insertion loss over temperature Measurement setup Cable of length 1 m is coiled on a conductive drum with 1 mm of Rohacell as insulation material Breakout-board ground is connected to conducting drum to close the common mode loop Thomas Müller (Rosenberger) 9

10 Cable insertion loss over temperature DUT overview 2 x.14 qmm 2 x.35 qmm STQ PVC jacket 2 x.14 qmm optimised jacket 2 x.35 qmm 2 x.17 qmm unjacketed note: every cable uses PP conductor insulation PVC jacket Thomas Müller (Rosenberger) 1

11 Insertion Loss per unit length [db/m] Cable insertion loss over temperature Results at room temperature 2 C x.14 qmm STQ 2 x.14 qmm optimised jacket 2 x.35 qmm unjacketed 2 x.35 qmm PVC jacket 2 x.17 qmm PVC jacket CAT6a CAT f [MHz] Unjacketed cables can provide low insertion loss at the expense of unstable balance and environmental robustness.14 qmm cables provide low insertion loss if they are shielded or jacketed with proper material Thomas Müller (Rosenberger) 11

12 Insertion Loss per unit length [db/m] Cable insertion loss over temperature Results at 125 C 125 C x.14 qmm STQ 2 x.14 qmm optimised jacket 2 x.35 qmm unjacketed 2 x.35 qmm PVC jacket 2 x.17 qmm PVC jacket CAT6a CAT f [MHz] PVC is not appropriate for high temperatures Cables with.14 qmm with optimised jacket material provide low insertion loss (~ 18% increase to room temperature) and high balance Thomas Müller (Rosenberger) 12

13 EMC Influence of inline connectors Measurement setup DUT 2. m GND GND NWA Measure differential and common mode coupling to stripline in a three port NWA measurement DUT length 2. m Both ends connected to ground plane Thomas Müller (Rosenberger) 13

14 Ssd21 [db] EMC Influence of inline connectors Results for standard cable and contacts -3-4 Typical 2 x.35 qmm unjacketed cable with standard contacts no inline inline f [MHz] 2 x.35 qmm unjacketed Typical unjacketed cable Thomas Müller (Rosenberger) 14

15 Ssd21 EMC Influence of inline connectors Results for optimised cable and connector x.14 qmm with optimised jacket and connector no inline inline f {MHz] 2 x.14 qmm unjacketed Optimised jacketed cable Thomas Müller (Rosenberger) 15

16 Ssd21 [db] EMC Influence of inline connectors Results for shielded cables and connectors -3-4 no inline inline STQ Ssd f [MHz] 4 x.14 qmm STQ Shielded cables and connectors provide best EMC performance Thomas Müller (Rosenberger) 16

17 + V - V EMC System simulation Outlook on stripline emission system simulation Port1 Port2 FC=.6GHz Port3 5 FC=.6GHz Name=in_diff Name=out 1 Gbit/s PRBS1 signal source.2 V peak to peak 25 ps rise time filter 3 rd order low pass (6 MHz) 3-port s-parameter file from stripline measurement Voltage probe at the stripline measurement output Thomas Müller (Rosenberger) 17

18 Ssd21 EMC System simulation Outlook on stripline emission system simulation -3 2 x.14 qmm with optimised jacket and connector no inline f {MHz] If input spectrum and transfer function to stripline are known, the emitted spectrum can be predicted Thomas Müller (Rosenberger) 18

19 + V - V EMC System simulation Outlook on stripline emission system simulation FC=3MHz Port1 Port3 Port2 5 Name=in_diff Name=out FC=3MHz Three bit sources combined.4 V peak to peak 25 ps rise time filter 3 rd order low pass (3 MHz) 3-port s-parameter file from stripline measurement Voltage probe at the stripline measurement output Thomas Müller (Rosenberger) 19

20 Ssd21 EMC System simulation Outlook on stripline emission system simulation -3 2 x.14 qmm with optimised jacket and connector no inline With PAM4, the input voltage can be increased while maintaining the same emission peak level Points which need to be looked at Detectors (e.g. peak, quasi-peak) Measurement time and bandwidth Quality and parameters of the source models f {MHz] Thomas Müller (Rosenberger) 2