THESIS
1998
xiii, 71 leaves : ill. ; 30 cm
Abstract
Varactor (variable reactor) is a key component extensively used in various microwave applications including voltage-controlled oscillator (VCO). Ordinary CMOS varactors make use of pn junction diode that suffers from low quality factor (Q factor) and limited tuning range which are not desirable for high spectral purity and wide frequency tuning range VCO. The design of a gated varactor on thin-film SO1 technology offers an experimentally highest Q factor of 14 which made a two to three times improvement to that of the conventional varactors. The fabrication of the SO1 gated varactor requires no special treatment to available SOI fabrication process....[
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Varactor (variable reactor) is a key component extensively used in various microwave applications including voltage-controlled oscillator (VCO). Ordinary CMOS varactors make use of pn junction diode that suffers from low quality factor (Q factor) and limited tuning range which are not desirable for high spectral purity and wide frequency tuning range VCO. The design of a gated varactor on thin-film SO1 technology offers an experimentally highest Q factor of 14 which made a two to three times improvement to that of the conventional varactors. The fabrication of the SO1 gated varactor requires no special treatment to available SOI fabrication process.
In this thesis, the capacitance-voltage characteristic on the giga-hertz range was investigated. Moreover, the effects of the gate length and gate bias to the performance of the gated varactors were studied. A proposed SOI gated varactor fabrication process flow was introduced. A similar varactor structure was also fabricated on 0.35 μm bulk CMOS technology which demonstrated a maximum Q factor of 22 at 2 GHz operating frequency.
To analyse the performance of this gated varactor on circuit application, an LC-tank VCO with two control terminals operated at 2 GHz using 0.35 μm bulk CMOS technology was fabricated. The VCO achieved a SSB phase noise of -87 dBc/Hz at 100 kHz offset from the carrier frequency and a wide tuning range of over 300 MHz.
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