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LT5558 Datasheet, PDF (1/16 Pages) Linear Technology – 600MHz to 1100MHz High Linearity Direct Quadrature Modulator | |||
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FEATURES
â Direct Conversion from Baseband to RF
â High OIP3: + 22.4dBm at 900MHz
â Low Output Noise Floor at 20MHz Offset:
No RF: â158dBm/Hz
POUT = 4dBm: â152.7dBm/Hz
â Low Carrier Leakage: â43.7dBm at 900MHz
â High Image Rejection: â49dBc at 900MHz
â 3 Channel CDMA2000 ACPR: â70.4dBc at 900MHz
â Integrated LO Buffer and LO Quadrature Phase
Generator
â 50Ω AC-Coupled Single-ended LO and RF Ports
â High Impedance Interface to Baseband Inputs
with 2.1V Common Mode Voltage
â 16-Lead QFN 4mm à 4mm Package
APPLICATIONS
â RFID Single-Sideband Transmitters
â Infrastructure TX for Cellular and ISM Bands
â Image Reject Up-Converters for Cellular Bands
â Low-Noise Variable Phase-Shifter for 600MHz to
1100MHz Local Oscillator Signals
â Microwave Links
LT5558
600MHz to 1100MHz
High Linearity Direct
Quadrature Modulator
DESCRIPTION
The LT®5558 is a direct I/Q modulator designed for high
performance wireless applications, including wireless
infrastructure. It allows direct modulation of an RF signal
using differential baseband I and Q signals. It supports
GSM, EDGE, CDMA, CDMA2000, and other systems. It
may also be conï¬gured as an image reject upconverting
mixer, by applying 90° phase-shifted signals to the I and
Q inputs. The high impedance I/Q baseband inputs consist
of voltage-to-current converters that in turn drive double-
balanced mixers. The outputs of these mixers are summed
and applied to an on-chip RF transformer, which converts
the differential mixer signals to a 50Ω single-ended output.
The balanced I and Q baseband input ports are intended
for DC coupling from a source with a common-mode
voltage level of about 2.1V. The LO path consists of an LO
buffer with single-ended input, and precision quadrature
generators which produce the LO drive for the mixers.
The supply voltage range is 4.5V to 5.25V.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
600MHz to 1100MHz Direct Conversion Transmitter Application
â« IDAC
EN
â« QDAC
VCC
8, 13
5V
2 x 100nF
14
16
V-1
I-CH
1
O°
LT5558
RF = 600MHz TO
1100MHz
11 PA
90°
7
Q-CH
5
V-1
BALUN
BASEBAND
GENERATOR
2, 4, 6, 9, 10,
12, 15, 17
3
VCO/SYNTHESIZER
5558 TA01
CDMA2000 ACPR, AltCPR and Noise vs
RF Output Power at 900MHz for 1 and 3 Carriers
â40
DOWNLINK TEST
MODEL 64 DPCH
â50
3-CH ACPR
3-CH ALTCPR
â60
â70
â110
â120
â130
1-CH ACPR
â140
â80
1-CH ALTCPR
1-CH NOISE
â150
3-CH NOISE
â90
â30 â25 â20 â15 â10 â5
â160
0
RF OUTPUT POWER PER CARRIER (dBm)
5558 TA01b
5558fa
1
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