Design of Gilbert-cell Mixer, I-Q Modulator, and SPDT Switch in 60-GHz Applications
Date Issued
2009
Date
2009
Author(s)
Tsai, Yi-Chien
Abstract
This thesis discusses Gilbert-cell down-conversion mixer, broadband I-Q modulator with improved sideband suppression, and a distributed single-pole-double-throw switch. The main purpose is to explore the frequency conversion components such as mixer and I-Q modulator, and improve the performance of quadrature coupler used in I-Q modulator to combine two orthogonal signals, and develop a broadband switch for high-frequency application at 60 GHz.n this thesis, a 60-GHz down-conversion Gilbert-cell mixer is discussed and fabricated. Modulators are important components in transmitters, recently reported modulators around 60 or 70 GHz normally emphasize their broadband property. 90? couplers are needed to modulate baseband signals with QPSK modulation. However, it is not easy for conventional broadside coupler to provide balanced output amplitude and accurate 90? output phase split in a very broadband fasion. Therefore, these modulators normally achieve high sideband suppression only in norrowband ranges. Making use of the phase lead property of a composite left/right hand transmission line, broadband quadrature power splitter can be designed. It can improve the sideband suppression of conventional modulators. Finally, single-pole-double-throw switches are important switching components in transceivers. A distributed SPDT switch using mHEMT process is fabricated. The insertion loss at 60 GHz is only 2 dB, which reduces the noise introduced by the switches in transceivers. To obtain low insertion loss, the SPDT switch use only three transistors for each SPST switch branch. As a trade-off from low insertion loss, the isolation is moderate.
Subjects
Gilbert-cell mixer
modulator
composite right/left hand transmission line
quadrature power combiner/splitter
sideband suppression
single-pole-double-throw switch
traveling-wave concept
Type
thesis
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