SKY72302-21 Datasheet, PDF (13/23 Pages) Skyworks Solutions Inc. – SKY72302-21: Spur-Free, 6.1 GHz Dual Fractional-N Frequency Synthesizer

DATA SHEET • SKY72302-21 FREQUENCY SYNTHESIZER
A3 A2 A1 A0 11 10 9 8 7 6 5 4 3 2 1 0
0111X X
MSB
LSB
Full Power Down
Main Synthesizer Power Down
Main Synthesizer Mode
Main Synthesizer ΔΣ Fractionality
Auxiliary Synthesizer Power Down
Auxiliary Synthesizer Mode
Multiplexer Output Selection
Mux_out Pin Tri-State Enable
C1424
Figure 13. Power Down and Multiplexer Output Register (Write Only)
x Main Synthesizer '6 Fractionality = One-bit flag to configure
the size of the main '6 modulator. This has a direct effect on
power consumption and on the level of fractionality and step
size. When this bit is cleared, the main '6 modulator is 18-bit
with a fractionality of 2¹⁸ and a step size of F_{ref_main}/262144.
When this bit is set, the main '6 modulator is 10-bit with a
fractionality of 2¹⁰ and a step size of F_{ref_main}/1024.
x Auxiliary Synthesizer Power Down = One-bit flag to power down
the auxiliary synthesizer. When this bit is cleared, the auxiliary
synthesizer is powered up. When this bit is set, the auxiliary
synthesizer is in power-down mode.
x Auxiliary Synthesizer Mode = One-bit flag to power down the
auxiliary synthesizer’s '6 modulator and fractional unit to
operate as an integer-N synthesizer. When this bit is cleared,
the auxiliary synthesizer is in fractional-N mode. When this bit is
set, the auxiliary synthesizer is in integer-N mode.
NOTE: There are no special power-up sequences required for the
SKY72302-21.
x Multiplexer Output Selection = Three-bit value that selects
which internal signal is output to the Mux_out pin. The following
internal signals are available on this pin:
 Reference oscillator, Fref
 Main or auxiliary divided reference (post-reference frequency
main or auxiliary dividers), F_{ref_main} or F_{ref_aux}
 Main or auxiliary phase detector frequency (post-main or
auxiliary frequency dividers), F_{pd_main} or F_{pd_aux}
 Serial data out, for loop-back and test purposes
Refer to Table 4 for more information.
x Mux_out Pin Tri-State Enable = One-bit flag to tri-state the
Mux_out pin. When this bit is cleared, the Mux_out pin is
enabled. When this bit is set, the Mux_out pin is tri-stated.
The Modulation Control Register is used to configure the
modulation unit of the main synthesizer The modulation unit adds
or subtracts a frequency offset to the selected center frequency at
which the main synthesizer operates. The size of the modulation
data sample, controlled by the duration of the CS signal, can be
from 2 to 12 bits wide, to provide from 4 to 4096 selectable
frequency offset steps.
The modulation data magnitude offset selects the magnitude
multiplier for the modulation data and can be from 0 to 8. As
shown in Figure14, the values to be loaded are:
x Modulation Data Magnitude Offset = Four-bit value that
indicates the magnitude multiplier (m) for the modulation data
samples. Valid values range from 0 to 13, effectively providing a
2^m multiplication of the modulation data sample.
x Modulation Data Input Select = One-bit flag to indicate the pin
on which modulation data samples are serially input when the
CS signal is between 2 and 12 bits long. When this bit is
cleared, modulation data samples are to be presented on the
Data pin. When this bit is set, modulation data samples are to
be presented on the Mod_in pin.
x Modulation Address Disable = One-bit flag to indicate the
presence of the address as modulation data samples are
presented on either the Mod_in or Data pins. When this bit is
cleared, the address is presented with the modulation data
samples (i.e., all transfers are 16 bits long). When this bit is set,
no address is presented with the modulation data samples (i.e.,
all transfers are 2 to 12 bits long).
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
101216L • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • September 9, 2009
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