Keysight E8267D User Manual page 292

Peripheral Devices
N5102A Digital Signal Interface Module
When the clock source is Internal, a frequency reference must be applied to the
Freq Ref connector. The frequency of this applied signal needs to be specified
using the Reference Frequency softkey, unless the current setting matches
that of the applied signal.
The selected clock source provides the interface module output clock signal at
the Clock Out and the Device Interface connectors.
Common Frequency Reference
The clocking flexibility of the digital signal interface module allows the setting
of arbitrary clock rates for the device under test. In general, the clock rate
inside the PSG will be different from the interface module clock rate, so the
interface module performs a rate conversion. An important aspect of this
conversion is to have accurate clock rate information to avoid losing data. The
module relies on relative clock accuracy, instead of absolute accuracy, that
must be ensured by using a single frequency reference for all clock rates
involved in the test setup. This can be implemented in various ways (see the
five drawings in Figure 12-3 on page 279), but whatever way it is implemented,
the clock inside the signal generator must have the same base frequency
reference as the clock used by the device under test.
PSG Frequency Reference Connections
When a frequency reference is connected to the PSG, it is applied to one of two
rear-panel connectors:
— 10 MHz IN
— BASEBAND GEN REF IN
The BASEBAND GEN REF IN connector will accept a frequency reference in the
range of 1 to 100 MHz. If the external or device under test clock source cannot
provide or accept a frequency reference, that clock signal can be applied to this
connector and used as the frequency reference.
Whenever an external clock signal or frequency reference is connected to the
BASEBAND GEN REF IN connector, its frequency needs to be entered into the
current signal generator modulation format. For information on the
BASEBAND GEN REF IN connector refer to "24. BASEBAND GEN CLK IN" on
page 37. For information on the associated softkeys and fields for entering the
frequency of the applied clock signal or frequency reference, refer to the
Keysight PSG Signal Generators Key Reference.
278 Keysight E8357D/67D & E8663D PSG User's Guide