LMX2486_16 Datasheet, PDF (1/47 Pages) Texas Instruments – Low-Power Dual PLLatinum Frequency Synthesizers

Product
Folder
Sample &
Buy
Technical
Documents
Tools &
Software
Support &
Community
LMX2486
SNAS324B – JANUARY 2006 – REVISED JANUARY 2016
LMX2486 1-GHz to 4.5-GHz High-Performance Delta-Sigma Low-Power Dual PLLatinum™
Frequency Synthesizers With 3-GHz Integer PLL
1 Features
• Quadruple Modulus Prescaler for Lower Divids
– RF PLL: 16/17/20/21 or 32/33/36/37
– IF PLL: 8/9 or 16/17
• Advanced Delta Sigma Fractional Compensation
– 12-Bit or 22-Bit Selectable Fractional Modulus
– Up to 4th Order Programmable Delta-Sigma
Modulator
• Improved Lock Times and Programming
– Fastlock / Cycle Slip Reduction Which
Requires Only a Single-Word Write
– Integrated Time-Out Counter
• Wide Operating Range
– LMX2486 RF PLL: 1.0 GHz to 4.5 GHz
• Useful Features
– Digital Lock Detect Output
– Hardware and Software Power-Down Control
– On-Chip Crystal Reference Frequency Doubler
– RF Phase Detector Frequency Up to 50 MHz
– 2.5-V to 3.6-V Operation With I_CC = 8.5 mA
2 Applications
• Cellular Phones and Base Stations
• Direct Digital Modulation Applications
• Satellite and Cable TV Tuners
• WLAN Standards
1
3 Description
The LMX2486 device is a low-power, high
performance delta-sigma fractional-N PLL with an
auxiliary integer-N PLL. The device is fabricated
using TI’s advanced process.
With delta-sigma architecture, fractional spurs at
lower offset frequencies are pushed to higher
frequencies outside the loop bandwidth. The ability to
push close in spur and phase noise energy to higher
frequencies is a direct function of the modulator
order. Unlike analog compensation, the digital
feedback technique used in the LMX2486 is highly
resistant to changes in temperature and variations in
wafer processing. The LMX2486 delta-sigma
modulator is programmable up to fourth order, which
allows the designer to select the optimum modulator
order to fit the phase noise, spur, and lock time
requirements of the system.
Serial data for programming the LMX2486 is
transferred through a three-line, high-speed (20-MHz)
MICROWIRE interface. The LMX2486 offers fine
frequency resolution, low spurs, fast programming
speed, and a single-word write to change the
frequency. This makes it ideal for direct digital
modulation applications, where the N-counter is
directly modulated with information. The LMX2486 is
available in a 24-lead 4.0 × 4.0 × 0.8 mm WQFN
package.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LMX2486
WQFN (24)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Functional Block Diagram
FinIF
ENOSC
OSCin
OSCout
VddRF1
VddRF2
VddRF3
VddRF4
VddRF5
FinRF
FinRF*
CE
CLK
DATA
LE
1X / 2X
IF N Divider
8/9
or
16/17
Prescaler
B Counter
A Counter
IF R
Divider
RF R
Divider
RF N Divider
16/17/20/21 C Counter
32/33o/r3R6/F3N7 ^{DividBerCounter}
Prescaler
A Counter
MICROWIRE
Interface
6'
Compensation
Phase
Comp
IF
LD
RF LD
Phase
Comp
Charge
Pump
Ftest/LD
MUX
Charge
Pump
RF Fastlock
VddIF1
VddIF2
CPoutIF
Ftest/LD
CPoutRF
FLoutRF
GND
GND
GND
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.