Design of Broadband Highly Linear IQ Modulator Using a 0.5$mu$m E/D-PHEMT Process for Millimeter-Wave Applications

摘要

A broadband highly linear IQ modulator using a 0.5- $mu$m enhancement/depletion-pseudomorphic high-electron mobility transistor process is presented in this letter. An innovative broadside/edge coupler is proposed to apply to the IQ modulator. The chip size is only 1$,times,$1 mm ${2}$, including radio frequency and baseband PADs. The sideband and local oscillation suppressions of the modulator are better than $-$33 and $-$15dBc, respectively. At a carrier frequency of 60 GHz with a 64 quadrature amplitude modulation (QAM) modulation, the modulator demonstrates an error vector magnitude of within 3%, and an adjacent channel power ratio of better than $-$40 dBc. To the best of the authors'' knowledge, this work demonstrates the best modulation quality with a 64QAM modulation up to 60 GHz among all the reported reflection-type IQ modulators.