
Tuning the reference
RF
Source Tuning the reference at the down converted
frequency is the most common method for creating a PLL with the
maximum PTR. In this case the reference VCO can be tuned using DC
FM or EFC. The maximum PTR allowed is limited by the following graph.
Q_
c
D
tx.
o*
c
"c
n
O
0-
2.5MHz
250kHz -
25kHz
10kHz
2.5kHz
250Hz
-
-
-
-
* I I
I ■ I
/ *
i i
c
y
'
MAX PTR
^
^
9^
V
ALLOWED
—\ 1—I
10MHz 100MHz 1GHz 10GHz 100GHz
Carrier Frequency
Figure 6-19. Graph of Limits for Maximum Peak Tuning Range Using EFC
reu.05SEP89
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