LMX2581E_15 Datasheet, PDF (1/55 Pages) Texas Instruments – LMX2581E Wideband Frequency Synthesizer with Integrated VCO

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LMX2581E
SNAS665 – MAY 2015
LMX2581E Wideband Frequency Synthesizer with Integrated VCO
1 Features
•1 Output Frequency from 50 to 3800 MHz
• Input Clock Frequency up to 900 MHz
• Phase Detector Frequency up to 200 MHz
• Supports Fractional and Integer Modes
• –229 dBc/Hz Normalized PLL Phase Noise
• –120.8 dBc/Hz Normalized PLL 1/f Noise
• –137 dBc/Hz VCO Phase Noise at 1 MHz offset
for a 2.5 GHz Carrier
• 100 fs RMS Jitter in Integer Mode
• Programmable Fractional Modulator Order
• Programmable Fractional Denominator
• Programmable Output Power up to 12 dBm
• Programmable 32 Level Charge Pump Current
• Programmable Option to Use an External VCO
• Digital Lock Detect
• 3-Wire Serial Interface and Readback
• Single Supply Voltage from 3.15 V to 3.45 V
• Supports Logic Levels down to 1.6 V
2 Applications
• Wireless Infrastructure (UMTS, LTE, WiMax,
Multi-Standard Base Stations)
• Broadband Wireless
• Test and Measurement
• Clock Generation
3 Description
The LMX2581E is a low-noise wideband frequency
synthesizer that integrates a delta-sigma fractional N
PLL, multiple core VCO, programmable output
divider, and two differential output buffers. The VCO
frequency range is from 1880 to 3800 MHz and can
be sent directly to the output buffers or divided down
by even values from 2 to 38. Each buffer is capable
of output power from –3 to +12 dBm at 2700 MHz.
Integrated low-noise LDOs are used for superior
noise immunity and consistent performance.
This synthesizer is a highly programmable device and
it enables the user to optimize its performance. In
fractional mode, the denominator and the modulator
order are programmable and can be configured with
dithering as well. The user also has the ability to
directly specify a VCO core or entirely bypass the
internal VCO. Finally, many convenient features are
included such as power down, Fastlock, auto mute,
and lock detection. All registers can be programmed
through a simple 3-wire interface and a read back
feature is also available.
The LMX2581E operates on a single 3.3 V supply
and comes in a 32 pin 5.0 mm × 5.0 mm WQFN
package.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMX2581E
WQFN (32) DAP 5.00 mm × 5.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
4 Simplified Schematic
Multiple
Core VCO
Vtune
RFin
Vcc
RFoutA
RFoutB
Vcc
OSCin
MUX
Fractional
N Divider
MUX
Output
Divider
MUX
2X
MUX
R
Divider
Charge
I
Pump
CPout
LD
MUXout
Serial Interface
Control
DATA
CLK
LE
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. PRODUCTION DATA.