Agilent Technologies E8257D PSG, E8267D PSG manual Clock Source Settings and Connectors

Peripheral Devices

N5102A Digital Signal Interface Module

Table 11-8 Clock Source Settings and Connectors

Clock Source	Softkeys		N5102A Module Connection
	Reference	Clock Ratea	Freq Ref	Ext Clock In	Device Interface
	Frequency
External		•		•
Device		•			•
Internalb	•	•	•

a.For the Internal selection, this sets the internal clock rate. For the External and Device selections, this tells the interface module the rate of the applied clock signal.

b.There should be no clock signal applied to the Ext Clock In connector.

6.Press the Clock Phase softkey.

From the menu that appears, you can adjust the phase of the clock relative to the data in

90 degree increments. The selections provide a coarse adjustment for positioning the clock on the valid portion of the data. Selecting 180 degrees is the same as selecting a negative clock polarity.

The 90 degree and 270 degree selections are not available when the clock rate is set below

10 MHz or above 200 MHz. If 90 degrees or 270 degrees is selected when the clock rate is set below 10 MHz or above 200 MHz, the phase will change to 0 degrees or 180 degrees, respectively.

NOTE The clock phase and clock skew may need to be adjusted any time the clock rate setting is changed. Refer to “Clock Timing for Phase and Skew Adjustments” on page 215.

7.Enter the required phase adjustment.

8.Press the Return softkey to return to the clock setup menu.

9.Press the Clock Skew softkey.

This provides a fine adjustment for the clock relative to its current phase position. The skew is a phase adjustment using increments of time. This enables greater skew adjustment capability at higher clock rates. For clock rates below 25 MHz, this softkey is inactive.

The skew has discrete values with a range that is dependent on the clock rate. Refer to “Clock Timing for Phase and Skew Adjustments” on page 215 for more information on skew settings.

10.Enter the skew adjustment that best positions the clock with the valid portion of the data.

11.Press the Clock Polarity Neg Pos softkey to Neg.

This shifts the clock signal 180 degrees, so that the data starts during the negative clock transition. This has the same affect as selecting the 180 degree phase adjustment.

12.Make the clock polarity selection that is required for the device being tested.

13.Press the Return hardkey to return to the first- level softkey menu.

The clock source selection is also reflected in the first- level softkey menu graphic. For example, if the device is the new clock source, the graphic will show that the frequency reference is now connected to the DUT and the DUT has an input clock line going to the N5102A module.

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