SKY72300-21 Datasheet, PDF (10/23 Pages) Skyworks Solutions Inc. – SKY72300-21: Spur-Free, 2.1 GHz Dual Fractional-N Frequency Synthesizer

DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER
A3 A2 A1 A0 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 0 X X X MSB
LSB
Main Synthesizer Divider Index
C1417
Figure 6. Main Divider Register (Write Only)
A3 A2 A1 A0 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 1 X X MSB
LSB
Main Synthesizer Dividend (MSBs)
C1418
Figure 7. Main Dividend MSB Register (Write Only)
A3 A2 A1 A0 11 10 9 8 7 6 5 4 3 2 1 0
0 0 1 0 X X X X MSB
LSB
Main Synthesizer Dividend (LSBs)
C1419
Figure 8. Main Dividend LSB Register (Write Only)
General Synthesizer Registers
The dual-programmable reference frequency dividers provide the
reference frequencies to the phase detectors by dividing the
crystal oscillator frequency. The lower five bits hold the reference
frequency divide index for the main phase detector. The next five
bits hold the reference frequency divide index for the auxiliary
phase detector. Divide ratios from 1 to 32 are possible for each
reference frequency divider (see Tables 2 and 3).
The Reference Frequency Dividers Register configures the dual-
programmable reference frequency dividers for the main and
auxiliary synthesizers. As shown in Figure 11, the values to be
loaded are:
x Main Reference Frequency Divider Index = Desired main
oscillator frequency division ratio –1. Default value on power up
is 0, signifying that the reference frequency is not divided for
the main phase detector.
x Auxiliary Reference Frequency Divider Index = Desired auxiliary
oscillator frequency division ratio –1. Default value on power up
is 0, signifying that the reference frequency is not divided for
the auxiliary phase detector.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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September 11, 2009 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 101217N