LT5572_15 Datasheet, PDF (1/16 Pages) Linear Technology – 1.5GHz to 2.5GHz High Linearity Direct Quadrature Modulator

FEATURES
■ _{Direct Conversion from Baseband to RF}
■ _{High Output: –2.5dB Conversion Gain}
■ _{High OIP3: +21.6dBm at 2GHz}
■ _{Low Output Noise Floor at 20MHz Offset:}
No RF: –158.6dBm/Hz
P_OUT = 4dBm: –152.5dBm/Hz
■ _{Low Carrier Leakage: –39.4dBm at 2GHz}
■ _{High Image Rejection: –41.2dBc at 2GHz}
■ _{4-Channel W-CDMA ACPR: –67.7dBc at 2.14GHz}
■ _{Integrated LO Buffer and LO Quadrature Phase}
Generator
■ _{50Ω AC-Coupled Single-Ended LO and RF Ports}
■ _{High Impedance DC Interface to Baseband Inputs}
with 0.5V Common Mode Voltage
■ _{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}
2.5GHz Local Oscillator Signals
LT5572
1.5GHz to 2.5GHz
High Linearity Direct
Quadrature Modulator
DESCRIPTIO
The LT5572 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 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
Direct Conversion Transmitter Application
I-DAC
EN
Q-DAC
14
16 V-I
I-CH
1
7 ^Q-CH
5 V-I
8, 13
V_CC
LT5572
11
0°
90°
BALUN
5V
100nF
×2 RF = 1.5GHz
TO 2.5GHz
PA
BASEBAND
GENERATOR
2, 4, 6, 9, 10, 12, 15, 17
3
VCO/SYNTHESIZER
5572 TA01a
W-CDMA ACPR, AltCPR and Noise
vs RF Output Power at 2.14GHz for
1, 2 and 4 Channels
–50
DOWNLINK TEST
MODEL 64 DPCH
4-CH ACPR
–60
4-CH AltCPR
2-CH ACPR
–125
1-CH
ACPR –135
–70
–145
2-CH AltCPR
1-CH AltCPR
–80
–155
2-CH NOISE
4-CH NOISE
1-CH NOISE
–90
–165
–30 –25 –20 –15 –10 –5
RF OUTPUT POWER PER CARRIER (dBm)
5572 TA01b
5572f
1