Information

Texas Instruments Signal Chain Guide 2013 | 143
Radio Frequency
Broadband RF
Get more information: www.ti.com/product/TRF371125
Get more information: www.ti.com/product/LMX2581
High-Linearity Direct-Conversion Quadrature Demodulator
TRF371125
Wideband Frequency Synthesizer with Integrated VCO
LMX2581
The TRF371125 is a highly linear and integrated direct-conversion quadrature demodu-
lator optimized for 3G/4G wireless infrastructure equipment. The TRF371125 integrates
balanced
IandQmixers,LObuffersandphasesplitterstoconvertanRFsignaldirectly
toIandQbaseband.Theon-chipprogrammablegainamplifiers(PGAs)allowadjust-
ment of the output signal level without the need for external variable gain (attenua-
tor) devices. The TRF371125 integrates programmable baseband low-pass filters that
attenuate nearby interfer
ence, eliminating the need for an external baseband filter.
Housedina7mmx7mmQFNpackage,theTRF371125providesthesmallestand
most integrated receiver solution available for high-performance equipment.
The LMX2581 is an ultra-low noise wideband frequency synthesizer which integrates a
delta-sigma fractional N PLL, a VCO with fully integrated tank circuit, and an optional
frequency divider.
The LMX2581 integrates several low-noise, high-precision LDOs to provide superior
supply noise immunity and more consistent performance. When combined with a high
quality reference oscillator, the LMX2581 generates a very stable, ultra-low noise signal.
The internal VCO can be bypassed so that an external VCO can be used.
Key Features
• Frequencyrange:0.7to4.0GHz
• Noisefigureof13.5dB(gain=40dB)
• IIP3of24dBm(gain=40dB)
• IIP2of60dBm(gain=40dB)
• BasebandPGAwith24dBofgain
range in 1 dB steps
• Software-programmablebaseband
filter (1 dB corner)
• ReceivesRFsignalbandwidthsfrom
1.4 MHz to 30 MHz
• IntegratedADCdriver
• DCoffsetcorrectioncapability
Applications
• Cellularbasestationreceivers
• Software-definedradios(SDRs)
• Testequipment
• Wirelesslocalloops
• High-linearitydirectdown-conversion
receivers
Key Features
• Lowvoltagelogiccompatibility
• Digitallockdetect
• 32-pinQFNpackage
• HighperformancePLL
• Broadbandmulti-coreVCO
• LownoiseVCOdivider
Applications
• FemtoandTETRAbasestations
• Softwaredefinedradio
• Vectorsignalanalyzerandgenerator
• Wirelesscommunications,dataaccess
card, LAN card and repeater
TRF371125 functional block diagram
LMX2581 functional block diagram
Charge
Pump
DATA
CLK
LE
CE
OSCin
Vtune
CPout
LD
Output
Divider
Comp
N Divider
2X
MUX
Serial Interface
Control
Fin
R
Divider
RFoutA
MUX
RFoutB
Multiple
Core VCO
MUX
MUX
BUFEN
MUXout
FLout
Low
Noise
LDO
TRF371125
Quadrature Demodulator
GC5016
GC5316
GC5018
AFE8406
ADS5232
ADS62P42
ADS5282
TCI6xxx
SerDes
TLK2501
TLK3134
ADC
ADC
TRF3761
LNA
LO2
RF
Antenna
90
0
VCO
PLL
DDC
DSP