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LMX2820
SNAS783 –JUNE 2020
LMX2820 22.4-GHz Wideband PLLatinum™ RF Synthesizer
With Phase Synchronization and JESD204B Support
1 Features
3 Description
The LMX2820 is a high-performance, wideband
synthesizer that can generate any frequency in the
range of 43.75 MHz to 22.4 GHz. The high-
performance PLL with figure of merit of –236 dBc/Hz
and high phase detector frequency can attain very
low in-band noise and integrated jitter. The high-
speed N-divider has no pre-divider, thus significantly
reducing the amplitude and number of spurs. There is
also a programmable input multiplier to mitigate
integer boundary spurs.
1
•
•
•
Output frequency: 43.75 MHz to 22.4 GHz
< 40-fs rms jitter (12 kHz – 95 MHz)
High-performance PLL
–
–
–
Figure of merit: –236 dBc/Hz
Normalized 1/f noise: –134 dBc/Hz
High phase detector frequency
–
–
400-MHz integer mode
300-MHz fractional mode
The LMX2820 allows users to synchronize the output
of multiple devices and also enables applications that
need deterministic delay between input and output.
The fast calibration algorithm greatly reduces the
VCO calibration time to under 5 µs, enabling systems
requiring fast frequency hopping. The LMX2820 can
generate or repeat SYSREF that is compliant to the
JESD204B standard, allowing for its use as a low-
noise clock source for high-speed data converters.
This synthesizer can also be used with an external
VCO. A direct PFD input pin is provided to support
offset mixing for low spurious transmission.
–
–
Programmable input multiplier
Direct PFD input for offset mixing support
•
•
•
•
•
< 5-µs fast VCO calibration time
Mute pin with 200-ns mute/unmute time
–40-dBc VCO leakage with doubler enabled
Support for external VCO up to 22 GHz
Synchronization of output phase across multiple
devices
•
Two differential RF outputs and one differential
SYSREF output for JESD204B support
The device runs from a single 3.3-V supply and has
integrated LDOs that eliminate the need for onboard
low-noise LDOs.
2 Applications
•
•
•
•
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Radar and electronic warfare
Device Information(1)
5G and mm-Wave wireless infrastructure
Microwave backhaul
PART NUMBER
PACKAGE
BODY SIZE (NOM)
Test and measurement equipment
High-speed data converter clocking
LMX2820
VQFN (48)
7.00 mm × 7.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Functional Block Diagram
OSCIN_P
OSCIN_N
÷1,2,..4095
÷1,2,..255
RFOUTA_P
RFOUTA_N
Charge
Pump
÷2,4,8,..,128
PFD
×2
x3,x4..x7
÷2
×2
MUTE
Lock
Detection
LD
RFOUTB_P
RFOUTB_N
÷2,4,8,..,128
N Divider
MUXOUT
SRREQ_P
SRREQ_N
CS#
SCK
SDI
SYSREF
Generation
Digital
Control
G4
Modulator
SROUT_P
SROUT_N
Phase Sync
CE
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. ADVANCE INFORMATION for pre-production products; subject to
change without notice.