LT5568-2 - GSM/EDGE Optimized, High Linearity Direct Quadrature Modulator

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.

Features

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 POUT = 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