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Evaluation and Analysis of Connector Performance for the Spacewire Back Plane

International SpaceWire Conference 2008 Nov.5 2008. Evaluation and Analysis of Connector Performance for the Spacewire Back Plane. Koji Shibuya Keitaro Yamagishi Hideyuki Oh-hashi Seiichi Saito Masaharu Nomachi. Contents. Introduction Connector Evaluation Board

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Evaluation and Analysis of Connector Performance for the Spacewire Back Plane

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  1. International SpaceWire Conference 2008 Nov.5 2008 Evaluation and Analysis of Connector Performancefor the Spacewire Back Plane Koji Shibuya Keitaro Yamagishi Hideyuki Oh-hashi Seiichi Saito Masaharu Nomachi

  2. Contents • Introduction • Connector Evaluation Board • Transmission Characteristics Evaluation • Crosstalk Evaluation • Eye-Pattern Waveform Analysis • Conclusion

  3. 1. Introduction SpaceWire backplane system Driver Receiver Daughter board Connector Backplane Backplane System

  4. ImpedanceMismatch Crosstalk 1. Introduction SpaceWire backplane connectors • Connectors which have been selected by the space qualified are NOT designedfor high-speed Signal Transmission purpose. • impedance mismatching and crosstalk are generated • Evaluation and Analysis of Connector Performance is important.

  5. 2. Connector Evaluation Board Evaluation system for a backplane connector PCB2 (Daughter board) PCB1(Backplane) Connector for spacewire backplane - PCB1 corresponds to a backplane. - PCB2 corresponds to a daughter board.

  6. 2. Connector Evaluation Board Measurement Setup

  7. 3. Transmission Characteristics Evaluation Pin assignment for the transmission characteristics evaluation Edge ofdaughter board A B C D E F G H Differential Pairs GND Pins Side view of evaluation board

  8. 3. Transmission Characteristics Evaluation Measurement Results of Return Loss and Insertion Loss Differential return loss (Sdd11) Differential insertion loss (Sdd21) • Differences between different pin assignments become remarkable in frequency range higher than 1GHz. • - The pin assignments using the long pins for signals cause characteristic degradation.

  9. 4. Crosstalk Evaluation Pin assignment for crosstalk evaluation No GND pins around the victim Differential Pairs (Victim) GND Pins Aggressive signal pins GND pins existing around the victim Static signal pins a b c d e

  10. 4. Crosstalk Evaluation Measurement Results of Crosstalk No GND pins around the victim GND pins existing around the victim The pin assignment of the GND pins around the differential pair is effective to reduce the crosstalk from the other signal.( 15dB or more ) Crosstalk can be dramatically reduced by ground pins around victim.

  11. 5. Eye-Pattern Waveform Analysis Waveform Simulation Model Signal Source Received signal DifferentialTransmission Lines DifferentialTransmission Lines DifferentialTransmission Lines Connector model Connector model • Assuming High Speed Back Plane System - 50 cm total trace - 3.125 Gbps data rate - 2 connectors • Pin Assignment - E (shortest pin) and H (longest pin)

  12. 5. Eye-Pattern Waveform Analysis Results of Analysis Pin Assignment E(Short pins) Pin Assignment H (Long pins) - Eye-Pattern of pin assignments E is better for transmission

  13. 6. Conclusion 1. The pin assignments using the long pins for signals cause characteristic degradation. 2. The pin assignment of the GND pins around the differential pair is effective to reduce the crosstalk from the other signals. 3. The eye-pattern waveforms were shown by the simulation. the 3Gbps backplane transmission is possible using the connector selected by the space qualified design. The connector selected by the space qualified design can use for the system of over Gbps high speed signal transmission via the backplane by suitable pin assignment design.

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