The AD8346 is a silicon RFIC I/Q modulator for use from 0.8 GHz to 2.5 GHz. Its excellent phase accuracy and amplitude balance allow high performance direct modulation to RF. The differential LO input is applied to a polyphase network phase splitter that provides accurate phase quadrature from 0.8 GHz to 2.5 GHz. Buffer amplifiers are inserted between two sections of the phase splitter to improve the signal-tonoise ratio. The I and Q outputs of the phase splitter drive the LO inputs of two Gilbert-cell mixers. Two differential V-to-I converters connected to the baseband inputs provide the baseband modulation signals for the mixers. The outputs of the two mixers are summed together at an amplifier which is designed to drive a 50 load.