700 MHz to 2700 MHz

Quadrature Modulator

AD8349

Rev. 0

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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 5.25 V

Pin compatible with AD8345/AD8346

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

COM1

COM1

LOIN

QBBP

QBBN

COM3

COM3

VPS2

LOIP

VPS1

ENOP

VOUT

COM3

COM2

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.