High Speed Characterization Report. DVI-29-x-x-x-xx Mated With DVI Cable

Transcription

1 High Speed Characterization Report DVI-29-x-x-x-xx Mated With DVI Cable REVISION DATE:

2 TABLE OF CONTENTS Introduction... 1 Product Description... 1 Overview... 2 Results Summary... 3 Time Domain Data... 3 Differential Impedance... 3 Single-Ended Impedance... 3 FEXT Digital Differential... 4 FEXT Analog Single Ended... 4 Risetime... 5 Risetime Differential Digital... 5 Risetime Single-Ended Analog... 5 Measurement Results... 6 Differential Impedance... 6 Single-Ended Impedance... 7 Test Procedures... 9 Fixturing... 9 Time Domain Testing Differential Impedance Single-Ended Impedance Differential FEXT Single Ended FEXT Risetime Equipment ii

3 Introduction This testing was performed to evaluate the electrical performance of the Samtec DVI Connector. Testing was performed on a DVI-29-S-A-B-FT (mated with a DVI cable assembly) in accordance to the DDWG Digital Visual Interface (DVI) Revision 1.0 Specification where applicable. Figure 1: Samples tested Testing was performed on both the 75 Ohm single-ended analog signals and the 100 Ohm Differential digital signals. For the 100 Ohm digital interface, differential time domain and frequency domain measurements were made. In the time domain, differential impedance and crosstalk were measured. Frequency domain measurements were preformed using TDA s IConnect software (Version 3.0) and include insertion loss (IL) and far end crosstalk (FEXT). All measurements were made utilizing a custom test fixture. Product Description The samples consisted of fully populated DVI connectors able to transmit and receive six differential digital signals and three analog channels (RGB) plus associated control signals. There are 24 digital contacts and 4 analog signals in a fully populated connector. There are 6 differential data channels plus a differential clock, 4 control signals, 5 grounds, and one NC in the digital section and RGB plus a clock in the analog section with an associated grounding feature. Refer to Figure 1 on this page for a picture of the DVI-29-S-A-B-FT sample. 1

4 Overview A sample connector was tested for impedance, crosstalk, and bandwidth. In all cases, the sample performed better than the DDWG Digital Visual Interface (DVI) Revision 1.0 Specification. See the summarized results in Table 1 below. Specification Measured results Specification limit Differential Impedance 111Ω 100Ω +/-15% Single-Ended Impedance 73Ω 75Ω +/- 10% FEXT Digital 2.1% <5% FEXT Analog 2.3% <3% Risetime Digital 131 psec <160 psec Risetime Analog 118 psec <140 psec Table 1: Results summary of DVI-29-S-A-B-FT testing 2

5 Results Summary Time Domain Data Differential Impedance Differential impedance measurements were performed using a filtered risetime of 330ps. Note that all measurements were performed with the connector assembled to the test fixture. Measurements were made with both the mated connector and without a mated connector. Signal Pair Impedance Specification Limit Data 2 111Ω 100Ω +/- 15% Table 2: Differential Impedance Measurements Single-Ended Impedance Single-ended impedance measurements were performed using a filtered risetime of 700ps. Note that all measurements were performed with the connector assembled to the test fixture. Measurements were made with both the mated connector and without a mated connector. Signal Impedance Specification Limit Red 73Ω 75Ω +/- 10% Table 3: Single Ended Impedance Measurements 3

6 FEXT Digital Differential The far end crosstalk was measured in the time domain, as a differential voltage, and then converted to a percentage and reported below in Table 3. The aggressor lines are Data 2+ and Data 2-, and the victim lines are Data 1+ and Data 1-. Incident Measured Percent Crosstalk Specification Limit Amplitude Amplitude 500 mv 10.4 mv 2.1% 5% Table 4: Percent Digital FEXT FEXT Analog Single Ended The single-ended far end crosstalk was measured in the time domain and converted to a percentage reported in Table 4. The aggressor line was Analog Red, and the victim line was Analog Green. Incident Measured Percent Crosstalk Specification Limit Amplitude Amplitude 250 mv 5.7 mv 2.3% 3% Table 5: Percent Analog FEXT 4

7 Risetime Risetime measurements were performed on both the analog and digital signals. These risetime measurements were converted to equivalent bandwidths using the formula: BW = 0.35/t rise The DVI connector was mounted on a test fixture and the response was measured at semi-rigid coax soldered to the mating connector. Risetime Differential Digital Signal Measured Risetime Equivalent Bandwidth Risetime Limit Bandwidth Limit Data 2+, Data ps 2.67 GHz 160 ps 2.2 GHz Table 6: Digital Differential Risetime Risetime Single-Ended Analog Signal Measured Risetime Equivalent Bandwidth Risetime Limit Bandwidth Limit Analog Red 118 ps 2.97 GHz 140 ps 2.5 GHz Table 7: Analog Single-Ended Risetime 5

8 Measurement Results Differential Impedance Figure 2: Plot of Zo verses distance of DVI Connector Differential Signal Data 2. Red curser is the end of the test fixture. Blue curser is the end of the board mounted DVI connector. There are four traces shown: open test fixture with no connector, test fixture with DVI connector not mated, test fixture with DVI connector mated to cable DVI connector, and a 100 Ohm reference. All waveforms are filtered to 330 ps. The large impedance spike is the connection of the cable connector to the semirigid coax. 6

9 Single-Ended Impedance Figure 3: Plot of Zo verses distance for the 75 Ohm Analog interface. The red cursor indicates the end of the test fixture. The blue cursor indicates the end of the board mounted DVI connector. There are 4 different waveforms shown: the open test fixture, the test fixture with the DVI connector mounted, the test fixture with a mated DVI fixture terminated into 75 Ohms, and the test fixture with the mated DVI connector terminated into 50 Ohms. These plots were filtered to 280 ps, a wider bandwidth than the specification requires so that the detail can be seen. 7

10 Figure 4: DVI analog Zo verses distance. This plot of the mated analog section of the DVI connector is filtered to 700 ps per the specification. The red cursor is in the connector region, and the blue cursor is in the 75 Ohm termination region. 8

11 Test Procedures Fixturing All measurements were performed using the custom test fixture in Figure 5. For some measurements, a commercially available DVI cable (Molex, PN P) was attached to the DVI connector mounted on the fixture. For some measurements, 50 Ohm semi-rigid coax was soldered to the pigtails of the mating DVI plug connector. See Figure 6 and 7. The custom test fixture consisted of 50 Ohm controlled impedance traces for the digital signals and 75 Ohm controlled impedance traces for the analog signals. All traces were of inch lengths. All active pins on the connector were brought out for test. All power and ground signals were grounded. Also included on the board were test and calibration structures of opens, shorts, resistive terminations, and through paths. All test traces were brought to test equipment via SMA connectors. The estimated bandwidth of the 2 inch 50 Ohm traces is 5.5 GHz. Estimated crosstalk is 0.2%. Figure 5: Test fixture used for testing the Samtec DVI connector. 9

12 Coax Cable DVI Cable Coax Cable TDT TDR Fig 19 Tektronix TDS E03 Ch1 & Ch2 SMA Launches Tektronix TDS E04 Ch3 & Ch4 Figure 6: Characterization test setup. For some measurements, two test fixtures and a commercially available DVI cable were used. For the remaining measurements, the mating connector had semirigid coax soldered directly to it eliminating the second test fixture and DVI cable. Coax Cable Coax Cable TDT TDR Fig 19 Tektronix TDS E03 Ch1 & Ch2 SMA Launches Tektronix TDS E04 Ch3 & Ch4 Figure 7: Characterization test setup. For the remaining measurements, the mating connector had semi-rigid coax soldered directly to it eliminating the second test fixture and DVI cable. 10

13 Time Domain Testing Differential Impedance The Tektronix TDS8000 oscilloscope was set up in differential TDR (time domain reflectometry) mode using 100 averages and a 4000-point record length. The horizontal scale was set to allow the near end connector and a portion of the cable to be displayed. The filtering function was set per the DVI specification at 330 ps. Differential measurements were made within the connector region. Single-Ended Impedance The Tektronix TDS8000 oscilloscope was set up in single-ended TDR (time domain reflectometry) mode using 100 averages and a 4000-point record length. The horizontal scale was set to allow the near end connector and a portion of the cable to be displayed. The filtering function was set per the DVI specification at 700 ps. Single-ended measurements were made within the connector region. Because of the heavy filtering employed in the specification, it was difficult to determine the location of the connector in the waveforms. Additional measurements were performed with a wider bandwidth, a 280 ps filter, so that the impedance of the connectors was discernable. Differential FEXT Far end crosstalk (FEXT) measurements were made using the Tektronix TDS8000 oscilloscope. Acquiring FEXT, a near end differential pair was driven with the oscilloscope. Its far end was terminated into a pair of 50 Ohm terminators. FEXT was measured on the adjacent differential pair at the far end (see Figure 8 on page 10). Measurements were filtered with a 330 ps filter in the TDA Systems IConnect Software. All unused ports were terminated. Single Ended FEXT Far end crosstalk (FEXT) measurements were made using the Tektronix TDS8000 oscilloscope. Acquiring FEXT, a near end signal was driven with the oscilloscope. Its far end was terminated into a 50 Ohm terminator. FEXT was measured on the adjacent signal at the far end (see Figure 8 on page 10). Measurements were filtered with a 700 ps filter in the TDA Systems IConnect Software. All unused ports were terminated. 11

14 Coax Cable Coax Cable TDT TDR Fig 19 Tektronix TDS E03 Ch1 & Ch2 SMA Launches Tektronix TDS E04 Ch3 & Ch4 Figure 8: FEXT was measured using the above setup. For differential measurements the driven pair was terminated into 50 Ohms, and the victim pair was measured on the scope. The scope was put into differential mode. For the single-ended crosstalk, a single channel of stimulus and measurement were used. The driven net was terminated into 50 Ohms. Risetime Risetime was measured by driving the TDR pulser through the fixture and connector and measuring the response at semi-rigid coax soldered to the DVI Connectors. Equipment Time Domain Testing Tektronix TDS8000 Oscilloscope Tektronix 80E03 Sampling Head Tektronix 80E04 TDR/Sampling Head 12