Electrical Performance Report 85 ohm Reference Impedance

Transcription

1 ERM S-DV Mates with ERF S-DV Description: Edge Rate Strip Series, 0.8mm Centerline 16mm Stack Height Samtec, Inc All Rights Reserved

2 TABLE OF CONTENTS Connector Overview... 1 Purpose... 1 Differential Return Loss... 2 Differential Insertion Loss... 3 Differential Impedance Profile... 4 New Albany IN USA SIG@samtec.com Report Revision: Samtec, Inc Page:ii All Rights Reserved

3 Connector Overview Edge Rate Strip Series 0.8mm (.0315 ) pitch interfaces (ERF8/ERM8 Series) are available in increments of 10 positions per row from 10 up to 70. Seventy-five positions per row are also available. ERF8/ERM8 series board-to-board spacing is available in 7mm ( ), 10mm (0.3935"), or 16mm (0.630") stack heights. The data in this report is applicable only to the 16mm (0.630 ) board-to-board spacing in 2:1 signal to ground ratio. Purpose This report presents the results of the 16mm ERM8/ERF8 connector response acquired in a 100 ohm differential measurement system transformed to an 85 ohm measurement system. The purpose is to show how Samtec products will operate in an 85 ohm system. The transformation process is described in Samtec Technical Note Transformation of Samtec Connector Test Data for 85 ohm Differential Impedance Applications Samtec, Inc Page:1 All Rights Reserved

4 Differential Return Loss Figure 1 shows the differential return loss for the 16mm ERM8/ERF8 connector with 100 ohm reference impedance and with 85 ohm reference impedance. Notice that this connector has a better match in a 100 ohm system up to approximately 4 GHz. db(tda_import_85..s(1,1)) db(s(1,1)) Differential Return Loss freq, GHz Figure 1. Differential Return Loss of Samtec 16mm ERM8/ERF8 Red 100 ohm Reference Impedance, Blue 85 ohm reference Impedance Samtec, Inc Page:2 All Rights Reserved

5 Differential Insertion Loss Figure 2 shows the differential insertion loss of the 16mm ERM8/ERF8 connector with 100 ohm reference impedance and with 85 ohm reference impedance. Notice that the difference in transmission performance is fairly minor. db(tda_import_85..s(2,1)) db(s(2,1)) Differential Insertion Loss freq, GHz Figure 2. Differential Insertion Loss of Samtec 16mm ERM8/ERF8 Red 100 ohm Reference Impedance, Blue 85 ohm reference Impedance Samtec, Inc Page:3 All Rights Reserved

6 Differential Impedance Profile Figure 3 shows the differential impedance profile of the 16mm ERM8/ERF8 connector with 100 ohm reference impedance and with 85 ohm reference impedance. The short length of 100 ohm test traces are visible after the 85 ohm transformation (blue trace) at about 0.15 nsec. It is important to note that the connector impedance response (between 0.3 nsec and 0.45 nsec) is not affected by the choice of the reference impedance. This is the reason that a SPICE model of the connector can be used in systems with a non-standard reference impedance such as 85 ohm differential. 120 Differential Impedance Profile TDA_import_85..TDR TDR time, nsec Figure 3. Differential Impedance Profile of 16mm ERM8/ERF8 Red 100 ohm Reference Impedance, Blue 85 ohm reference Impedance Samtec, Inc Page:4 All Rights Reserved