LT5568_15 Datasheet, PDF (1/16 Pages) Linear Technology – 700MHz – 1050MHz High Linearity Direct Quadrature Modulator

FEATURES
■ _{Frequency Range: 700MHz to 1050MHz}
■ _{High OIP3: +22.9dBm at 850MHz}
■ _{Low Output Noise Floor at 5MHz Offset:}
No RF: –160.3dBm/Hz
P_OUT = 4dBm: –154dBm/Hz
■ _{3-Ch CDMA2000 ACPR: –71.4dBc at 850MHz}
■ _{Integrated LO Buffer and LO Quadrature Phase}
Generator
■ _{50Ω AC-Coupled Single-Ended LO and RF Ports}
■ _{50Ω DC Interface to Baseband Inputs}
■ _{Low Carrier Leakage: –43dBm at 850MHz}
■ _{High Image Rejection: –46dBc at 850MHz}
■ _{16-Lead 4mm × 4mm QFN Package}
U
APPLICATIO S
■ _{Infrastructure Tx for Cellular Bands}
■ _{Image Reject Up-Converters for Cellular Bands}
■ _{Low-Noise Variable Phase-Shifter for 700MHz to}
1050MHz Local Oscillator Signals
■ _{RFID Reader}
LT5568
700MHz – 1050MHz High
Linearity Direct Quadrature
Modulator
DESCRIPTIO
The LT^®5568 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 upconverting mixer, by applying
90° phase-shifted signals to the I and Q inputs. The 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 four balanced I and Q
baseband input ports are intended for DC coupling from a
source with a common mode voltage level of about 0.5V.
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
700MHz to 1050MHz Direct Conversion Transmitter Application
I-DAC
EN
Q-DAC
V_CC
V-I
I-CHANNEL
0°
90°
Q-CHANNEL
V-I
LT5568
BALUN
5V
100nF
x2 _{RF = 700MHz}
TO 1050MHz
PA
BASEBAND
GENERATOR
VCO/SYNTHESIZER
5568 TA01
CDMA2000 ACPR, AltCPR and Noise vs RF
Output Power at 850MHz for 1 and 3 Carriers
–50
DOWNLINK TEST MODEL 64 DPCH _1-CH.
ACPR
–125
–60
3-CH. ACPR
–135
–70
–145
3-CH. AltCPR
–80
1-CH. AltCPR –155
3-CH. NOISE
1-CH. NOISE
–90
–165
–30 –25 –20 –15 –10 –5
RF OUTPUT POWER PER CARRIER (dBm)
5568 TA02
5568f
1