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LT5571 - 620MHz - 1100MHz High Linearity Direct Quadrature Modulator

The LT5571 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 RFID, GSM, EDGE, CDMA, CDMA2000, 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 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 at 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.

Features Direct Conversion from Baseband to RF High Output: –4.2dB Conversion Gain High OIP3: 21.7dBm at 900MHz Low Output Noise Floor at 20MHz Offset: No RF: –159dBm/Hz POUT = 4dBm: –153.3dBm/Hz Low Carrier Leakage: –42dBm at 900MHz High Image Rejection: –53dBc at 900MHz 3-Ch CDMA2000 ACPR: –70.4dBc at 900MHz Integrated LO Buffer and LO Quadrature Phase Generator 50Ω AC-Coupled Single-Ended LO and RF Ports High Impedance DC Interface to Baseband Input with 0.5V Common Mode Voltage 16-Lead QFN 4mm × 4mm Package Typical Application

Applications RFID Interrogators GSM, CDMA, CDMA2000 Transmitters Point-to-Point Wireless Infrastructure Tx Image Reject Up-Converters for Cellular Bands Low-Noise Variable Phase-Shifter for 620MHz to 1100MHz Local Oscillator Signals Packaging

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