| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 94 === This thesis investigates V-band miniature mixers. The topology of mixer includes sub-harmonically pumped resistive mixer, CPW sub-harmonically pumped diode mixer and sub-harmonically pumped image rejection mixer. All of the mixers are operated frequency at V-band. The sub-harmonically pumped image rejection mixer contains a miniature Marchand balun. These circuits were fabricated by Win Semiconductor 0.15 μm GaAs pHEMT technology.
The sub-harmonically pumped resistive mixer was connected drains of a pair of transistors. The LO signal was used fundamental Marchand Balun to offer the 0o and 180o differential phases at gate. The RF signal at drain was fed by Power divider and mixed with LO signal, and then used diplexing circuit to draw out the IF signal. This work can provide good LO to IF isolation, LO to RF isolation and suppress high order harmonics. This mixer has a good conversion loss and miniature chip size. The CPW sub-harmonically pumped diode mixer was used finite ground CPW that can reduce radiation loss, suppress high order harmonics and be more convenient to layout. The sub-harmonically pumped image rejection mixer contained two single-balanced sub-harmonically mixers and the LO signal fed by a miniature dual Balun to offer the 0o and 180o differential phases. The RF signal was fed by Lange coupler to offer 90o phase shift. The IF port was fed by 90o hybrid circuit to combine two single-balanced sub-harmonically mixers’ IF signal, which was out of chip. This work has a miniature dual Balun saving the 76% area from fundamental dual Balun. Therefore, the mixer is a miniature area sub-harmonically pumped image rejection mixer.
The measured results of mixers are as follows; for the sub-harmonically pumped resistive mixer, the conversion loss is 13.22 dB, input power at the 1-dB gain compression point is 3 dBm, input third order intermodulation intercept point is 22 dBm, LO to IF isolation is greater than 40dB, LO to RF isolation is greater than 35 dB, and RF to IF isolation is greater than 15 dB. For CPW sub-harmonically pumped diode mixer, in up-converter operation, the conversion loss is 12.75 dB, input power at the 1-dB gain compression point is 3 dBm. In down-converter operation, the conversion loss is 14.71 dB, input power at the 1-dB gain compression point is 5 dBm, input third order inter-modulation intercept point is 28 dBm, LO to IF isolation is greater than 15 dB, LO to RF isolation is greater than 20 dB, and RF to IF isolation is greater than 15 dB. The frequency of sub-harmonically pumped image rejection mixer is shifted to 42.5 GHz The measured conversion loss is 8.4 dB, input power at the 1-dB gain compression point is 2.5 dBm, input third order inter-modulation intercept point is 26 dBm, port to port isolations are greater than 25 dB, and best image rejection rate is achieved as 26.2 dB.
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