LTC5598
1
5598f
TYPICAL APPLICATION
DESCRIPTION
5MHz to 1600MHz
High Linearity Direct
Quadrature Modulator
The LTC
®
5598 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
point-to-point microwave link, GSM, EDGE, CDMA,
700MHz band LTE, CDMA2000, CATV applications and
other systems. It may also be confi gured 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 a buffer, which converts the differential mixer signals
to a 50Ω single-ended buffered RF 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 or differential inputs, and precision
quadrature generators that produce the LO drive for the
mixers. The supply voltage range is 4.5V to 5.25V, with
about 168mA current.
5MHz to 1600MHz Direct Conversion Transmitter Application
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
FEATURES
APPLICATIONS
n
Frequency Range: 5MHz to 1600MHz
n
High Output IP3: +27.7dBm at 140MHz
+22.9dBm at 900MHz
n
Low Output Noise Floor at 6MHz Offset:
No Baseband AC Input: –161.2dBm/Hz
P
OUT
= 5.5dBm: –160dBm/Hz
n
Low LO Feedthrough: –55dBm at 140MHz
n
High Image Rejection: –50.4dBc at 140MHz
n
Integrated LO Buffer and LO Quadrature Phase
Generator
n
50Ω Single-Ended LO and RF Ports
n
>400MHz Baseband Bandwidth
n
24-Lead QFN 4mm × 4mm Package
n
Pin-Compatible with Industry Standard Pin-Out
n
Shut-down Mode
n
Point-to-Point Microwave Link
n
Military Radio
n
Basestation Transmitter GSM/EDGE/CDMA2K
n
700MHz LTE Basestation Transmitter
n
Satellite Communication
n
CATV/Cable Broadband Modulator
n
13.56MHz/UHF RFID Modulator
90o
0o
LTC5598
10nF
50Ω
10nF 470nF
10nF
BASEBAND
GENERATOR
PA
RF = 5MHz
TO 1600MHz
1nF
x2
4.7μF
x2
EN
5V
V-I
V-I
I-CHANNEL
Q-CHANNEL
V
CC
5598 TA01
I-DAC
Q-DAC
VCO/SYNTHESIZER
RF OUTPUT POWER (dBm)
NOISE FLOOR AT 6MHz OFFSET (dBm/Hz)
–152
–154
–156
–158
–160
–162
5598 TA02
8246–4 –2 0–12 –10 –8 –6–14
f
LO
= 140MHz; f
BB
= 2kHz; CW (NOTE 3)
20dBm
19.3dBm
13.4dBm
10.4dBm
8.4dBm
6.4dBm
Noise Floor vs RF Output Power
and Differential LO Input Power
