Analog Devices LT5568-2 Product Info

• Optimized Image Rejection for 850MHz to 965MHz
• High OIP3: +22.9dBm at 900MHz
• Low Output Noise Floor at 5MHz Offset:
• No RF: –159.4dBm/Hz
• P_OUT = 4dBm: –153dBm/Hz
• Integrated LO Buffer and LO Quadrature Phase Generator
• 50Ω AC-Coupled Single-Ended LO and RF Ports
• 50Ω DC Interface to Baseband Inputs
• Low Carrier Leakage: –43dBm at 900MHz
• High Image Rejection: –52dBc at 900MHz
• 16-Lead 4mm × 4mm QFN Package

The LT5568-2 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 GSM, EDGE, CDMA, CDMA2000 and other systems that operate in the 850MHz to 965MHz band. It may be configured 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 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 level of 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

• Infrastructure Tx for GSM/Cellular Bands
• Image Reject Up-Converters for Cellular Bands
• Low-Noise Variable Phase-Shifter for 700MHz to 1050MHz Local Oscillator Signals
• RFID Reader