herunterladen
700 MHz to 2700 MHz
Quadrature Modulator
AD8349
Rev. A
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However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
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Tel: 781.329.4700
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Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
Output frequency range: 700 MHz to 2700 MHz
Modulation bandwidth: dc to 160 MHz (large signal BW)
1 dB output compression: 5.6 dBm @ 2140 MHz
Output disable function: output below –50 dBm in < 50 ns
Noise floor: –156 dBm/Hz
Phase quadrature error: 0.3 degrees @ 2140 MHz
Amplitude balance: 0.1 dB
Single supply: 4.75 V to 5.5 V
Pin compatible with AD8345/AD8346s
16-lead, exposed-paddle TSSOP package
APPLICATIONS
Cellular/PCS communication systems infrastructure
WCDMA/CDMA2000/PCS/GSM/EDGE
Wireless LAN/wireless local loop
LMDS/broadband wireless access systems
FUNCTIONAL BLOCK DIAGRAM
IBBP
IBBN
C
OM1
C
OM1
LOIN
QBBP
QBBN
COM3
COM3
VPS2
LOIP
VPS1
ENOP
VOUT
COM3
COM2
03570-0-001
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
Σ
AD8349
PHASE
SPLITTER
BIAS
Figure 1.
PRODUCT DESCRIPTION
The AD8349 is a silicon, monolithic, RF quadrature modulator
that is designed for use from 700 MHz to 2700 MHz. Its
excellent phase accuracy and amplitude balance enable high
performance direct RF modulation for communication systems.
The differential LO input signal is buffered, and then split into
an in-phase (I) signal and a quadrature-phase (Q) signal using a
polyphase phase splitter. These two LO signals are further
buffered and then mixed with the corresponding I channel and
Q channel baseband signals in two Gilbert cell mixers. The
mixers’ outputs are then summed together in the output
amplifier. The output amplifier is designed to drive 50 Ω loads.
The RF output can be switched on and off within 50 ns by
applying a control pulse to the ENOP pin.
The AD8349 can be used as a direct-to-RF modulator in digital
communication systems such as GSM, CDMA, and WCDMA
base stations, and QPSK or QAM broadband wireless access
transmitters. Its high dynamic range and high modulation
accuracy also make it a perfect IF modulator in local multipoint
distribution systems (LMDS) using complex modulation
formats.
The AD8349 is fabricated using Analog Devices’ advanced
complementary silicon bipolar process, and is available in a 16-
lead, exposed-paddle TSSOP package. Its performance is
specified over a –40°C to +85°C temperature range.
