LT5518_15 Datasheet, PDF (1/16 Pages) Linear Technology – 1.5GHz–2.4GHz High Linearity Direct Quadrature Modulator

LT5518
1.5GHz–2.4GHz
High Linearity Direct
Quadrature Modulator
FEATURES
■ _{High Input Impedance Version of the LT5528}
■ _{Direct Conversion to 1.5GHz – 2.4GHz}
■ _{High OIP3: 22.8dBm at 2GHz}
■ _{Low Output Noise Floor at 20MHz Offset:}
No RF: –158.2dBm/Hz
P_OUT = 4dBm: –152.5dBm/Hz
■ _{4-Ch W-CDMA ACPR: –64dBc at 2.14GHz}
■ _{Integrated LO Buffer and LO Quadrature Phase}
Generator
■ _{50Ω AC-Coupled Single-Ended LO and RF Ports}
■ _{Low Carrier Leakage: –49dBm at 2GHz}
■ _{High Image Rejection: 40dB at 2GHz}
■ _{16-Lead QFN 4mm × 4mm Package}
U
APPLICATIO S
■ _{Infrastructure Tx for DCS, PCS and UMTS Bands}
■ _{Image Reject Up-Converters for DCS, PCS and UMTS}
Bands
■ _{Low Noise Variable Phase-Shifter for 1.5GHz to}
2.4GHz Local Oscillator Signals
DESCRIPTIO
The LT^®5518 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 PHS,
GSM, EDGE, TD-SCDMA, CDMA, CDMA2000, W-CDMA
and other systems. It may also be configured as an image
reject up-converting 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 that produce
the LO drive for the mixers. The supply voltage range is
4.5V to 5.25V.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
1.5GHz to 2.4GHz Direct Conversion Transmitter Application
with LO Feedthrough and Image Calibration Loop
W-CDMA ACPR, AltCPR and Noise vs RF Output
Power at 2140MHz for 1 and 4 Channels
I-DAC
EN
Q-DAC
14
16 V-I
V_{CC 8, 13}
LT5518
5V
100nF
×2 _{RF = 1.5GHz}
TO 2.4GHz
I-CHANNEL
1
0°
90°
7 ^Q-CHANNEL
5 V-I
BALUN
11
PA
LO FEEDTHROUGH
CAL OUT
IMAGE CAL OUT
CAL
BASEBAND
GENERATOR
2, 4, 6, 9, 10, 12, 15, 17
3
VCO/SYNTHESIZER
ADC
5518 TA01a
–55
4-CH ACPR
–135
–60
–140
4-CH ALTCPR
–65
–145
1-CH ACPR
–70
–150
–75
1-CH ALTCPR
–80 4-CH NOISE
–155
1-CH NOISE
–160
DOWNLINK TEST MODEL 64 DPCH
–85
–34 –30 –26 –22 –18 –14 –10
RF OUTPUT POWER PER CARRIER (dBm)
–165
5518 TA01b
5518f
1