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 configured 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.

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

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.