Kikusui KJM6310, Operation Manual

Page: 29 / 56

KJM6310 Operation 3-11
3.5 Delay Adjustment
When measuring the RF signal jitter with respect to the clock signal,
it is ideal for the average phase difference between the clock edge and
RF signal edge to be 180
°
.
Fig.3-11
Fig.3-12
Fig. 3-11 and Fig. 3-12 show the timing charts for the cases when the
phase difference between the RF and clock signals is 180 ° and 330 ° ,
respectively. Naturally, the jitter should be distributed over the range
of 0 ° to 360 ° as shown in Fig. 3-11. However, the distribution crosses
0 ° and 360 ° in Fig. 3-12 resulting in a large sigma value. Proper jitter
measurements are not possible in such conditions. Therefore, adjust-
ment must be made so that the average phase difference between the
two signals is 180 ° .
The delay circuit is used to make this adjustment.
The delay circuit places an appropriate delay on the clock signal, and
the average phase difference between the two signals can be made
180 ° .
RF
Clock OK
360
°
The distribution of the time
difference from the RF edge
to the clock
180
°
0
°
RF
Clock NG
360
°
330
°
0
°