DATA SHEET
SKY72300-362: Spur-Free, 2.1 GHz Dual Fractional-N
Frequency Synthesizer
Applications
•
General purpose RF systems
•
2.5G and 3G wireless infrastructure
•
Broadband wireless access
•
Low bit rate wireless telemetry
•
Instrumentation
•
L-band receivers
•
Satellite communications
•
Direct digital modulation
•
3 V operation
•
5 V output to loop filter
•
QFN (24-pin, 4 x 4 mm) Pb-free (MSL3, 260
°C
per JEDEC J-
STD-020) package
Description
Skyworks SKY72300-362 direct digital modulation fractional-N
frequency synthesizer provides ultra-fine frequency resolution,
fast switching speed, and low phase-noise performance. This
synthesizer is a key building block for high-performance radio
system designs that require low power and fine step size.
The ultra-fine step size of less than 100 Hz allows this synthesizer
to be used in very narrowband wireless applications. With proper
temperature sensing or through control channels, the
synthesizer’s fine step size can compensate for crystal oscillator
or Intermediate Frequency (IF) filter drift. As a result, crystal
oscillators or crystals can replace temperature-compensated or
ovenized crystal oscillators, reducing parts count and associated
component cost. The device’s fine step size can also be used for
Doppler shift corrections.
The SKY72300-362 has a phase noise floor of –90 dBc/Hz up to
2.1 GHz operation as measured inside the loop bandwidth. This is
permitted by the on-chip low noise dividers and low divide ratios
provided by the device’s high fractionality.
Reference crystals or oscillators up to 50 MHz can be used with
the SKY72300-362. The crystal frequency is divided down by
independent programmable dividers (1 to 32) for the main and
auxiliary synthesizers. The phase detectors can operate at a
maximum speed of 25 MHz, which allows better phase noise due
to the lower division value. With a high reference frequency, the
loop bandwidths can also be increased. Larger loop bandwidths
improve the settling times and reduce in-band phase noise.
Therefore, typical switching times of less than 100 s can be
achieved. The lower in-band phase noise also permits the use of
lower cost Voltage Controlled Oscillators (VCOs) in customer
applications.
The SKY72300-362 has a frequency power steering circuit that
helps the loop filter to steer the VCO when the frequency is too
fast or too slow, further enhancing acquisition time.
Features
•
Spur-free operation
•
2.1 GHz maximum operating frequency
•
500 MHz maximum auxiliary synthesizer
•
Ultra-fine step size, 100 Hz or less
•
High internal reference frequency enables large loop bandwidth
implementations
•
Very fast switching speed (e.g., below 100
µs)
•
Phase noise to –91 dBc/Hz inside the loop filter bandwidth
@ 1800 MHz
•
Software programmable power-down modes
•
High-speed serial interface up to 100 Mbps
•
Three-wire programming
•
Programmable division ratios on reference frequency
•
Phase detectors with programmable gain to provide a
programmable loop bandwidth
•
Frequency power steering further enhances rapid acquisition
time
•
On-chip crystal oscillator
•
Frequency adjust for temperature compensation
Skyworks offers lead (Pb)-free RoHS (Restriction of
Hazardous Substances) compliant packaging.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
200731B • Skyworks Proprietary and Confidential information • Products and Product Information are Subject to Change Without Notice • July 30, 2007
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SKYWORKS [ SKYWORKS SOLUTIONS INC. ]
