PS2500 2.2 GHz Fractional-N Frequency Synthesizer
- 21 -
Philsar Semiconductor Inc.
146 Colonnade Road S.
Nepean, Ontario, Canada
K2E 7Y1
Tel: 613-274-0922
Fax: 613-274-0915
www.philsar.com
PMP-001-DS2 V1.2
Auxiliary Synthesizer Registers
Figure 7: Hex3 Auxiliary Divider Register (Write only)
This register contains the integer portion closest to the desired fractional-N (or integer-N) value minus 32
for the auxiliary synthesizer. This register, in conjunction with the auxiliary dividend register, which
controls the fraction offset (from - 0.5 to + 0.5) permits selection of a precise frequency.
Values to be loaded are:
• Auxiliary Synthesizer Divider Index = 9-bit value for the integer portion of the auxiliary synthesizer
dividers. Valid values for this register are from 6 to 505 (fractional-N) or from 0 to 511 (integer-N).
Figure 8: Hex4 Auxiliary Dividend Register (Write only)
This register controls the fraction part of the desired fractional-N value and permits an offset of - 0.5 to +
0.5 to the auxiliary integer selected through the Auxiliary Divider Register.
Values to be loaded are:
• Auxiliary Synthesizer Dividend = 10-bit value for the dividend for the auxiliary synthesizer.
For information on programming these registers, see “Synthesizer Register Programming” on page 6. For
information on loading order for these registers, see “Register Loading Order” on page 9.
Auxiliary Synthesizer Divider Index
A3
0
1
2
3
4
5
6
7
8
9
10
11
0
A0
A1
A2
0
1
1
X
X
X
Auxiliary Synthesizer Dividend
A3
0
1
2
3
4
5
6
7
8
9
10
11
0
A0
A1
A2
1
0
0
X
X
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