Agilent Technologies E8257D PSG, E8267D PSG manual

Peripheral Devices

N5102A Digital Signal Interface Module

For the External selection, the signal is supplied by an external clock source and applied to the Ext Clock In connector. For the Device selection, the clock signal is supplied through the Device Interface connector, generally by the device being tested.

If Internal is Selected

Using an external frequency reference, the N5102A module generates its own internal clock signal. The reference frequency signal must be applied to the Freq Ref connector on the digital module.

a.Press the Reference Frequency softkey and enter the frequency of the externally applied frequency reference.

b.Press the Clock Rate softkey and enter the appropriate clock rate.

Table 11- 9 provides a quick view of the settings and connections associated with each clock source selection.

Table 11-9 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 when Internal is being used.

4.Press the Clock Phase softkey.

From the menu that appears, the phase of the clock relative to the data can be changed 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.

5.Enter the required phase adjustment.

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

7.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.

Chapter 11 233