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In this paper, three kinds of Kalpha/Ku-band Gilbert mixers are demonstrated using 0.15- mum AlGaAs/InGaAs pseudomorphic high electron mobility transistor technology. Thanks to the semiinsulating GaAs substrate, microwave passive components have a low-loss feature, and polyphase filters work up to higher frequencies. Highly accurate tantalum-nitride thin-film resistors utilized in polyphase filters result in perfect quadrature operation. Therefore, our proposed single-sideband up-converter operates at 15 GHz with a 63-dB sideband rejection ratio, and another 34-GHz in-phase/quadrature (I/Q) subharmonic down-converter reaches <0.4-dB magnitude and < 1deg phase errors. More than 50-dB local oscillator (LO) leakage suppression is achieved in the I/Q subharmonic mixer. On the other hand, a 40-GHz stacked-LO subharmonic mixer with a novel compensation technique is also proposed and demonstrated to improve LO speed and reduce the amount of transistors, as compared to previous work.
Microwave Theory and Techniques, IEEE Transactions on (Volume:57 , Issue: 5 )
Date of Publication: May 2009