Demonstration circuit 729 is an I/Q modulator featuring the LT5528. The LT5528 is a 1.5GHz to 2.4GHz direct I/Q modulator designed for high performance wireless applications, including wireless infrastructure. It may also be configured as an image reject upconverting mixer, by applying 90° phaseshifted signals to the I and Q inputs. A high-speed, internally matched LO amplifier drives two double-balanced mixer cores, allowing the use of a low power, single-ended LO source. It allows direct modulation of an RF signal using differential baseband I and Q signals. It supports GSM, EDGE, CDMA, CDMA2000, W-CDMA, 64-QAM, OFDM and other modulation formats. 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 50W single-ended output. The four balanced I and Q base-band input ports are intended for DC coupling from a source with a common-mode voltage level of about 0.5V. The differential input impedance of the baseband inputs is approximately 90W, making them ideally suited for current-drive applications. The LO path consists of an LO buffer with singleended input, and precision quadrature generators which produce the LO drive for the mixers. Demonstration circuit 729 is designed for an RF output frequency range from 1.5GHz to 2.4GHz.