W3000 PLL Dual-Band Frequency Synthesizer
Advance Data Sheet
December 1999
PLL Programming Information
The oscillator frequency is selected according to the following expression:
f
VCO
=
where:
f
VCO
= VCO frequency
[
(P * M)
+
A
]
* f
REF
R
P/(P + 1) = Dual modulus prescaler
M
A
= Programmable counter ratio (2 to 2047), M > A
= Swallow counter ratio (0 to M – 1 or 127)
= External reference oscillator frequency
= Reference counter ratio (2 to 2047)
f
REF
R
Example
You wish to have a VCO operating at 1172 MHz, ability to step the frequency in 200 kHz steps, and a reference
clock at 13 MHz.
Step 1:
Calculate the reference counter ratio R
R
=
13 MHz
=
65
200 kHz
Step 2: Calculate M & A
f
VCO
=
1172
=
[
(P * M)
+
A
]
* f
REF
R
[
(64 * M)
+
A
]
* 13
65
1172 * 65
=
5860
13
(64 * M
+
A )
=
5860
36
=
91
64
64
M is an integer, and so is A; therefore, M = 91, and A = 36.
8
Lucent Technologies Inc.
AGERE [ AGERE SYSTEMS ]
