| Summary: | 碩士 === 國立東華大學 === 電機工程學系 === 93 === Especially in recent years, the popularized of the wireless applications and portable devices, the issues of the low supply voltage RF transceiver becomes the major trend in wireless communication system design. For the wireless transceiver, the quality of the synthesizer effects the performance of the transceiver. The tunable frequency characteristic of the frequency synthesizer can be used in the multi-band transceiver system owning several frequency bands.
This paper presents the development of 5GHz U-NII band CMOS frequency synthesizer for 802.11a WLAN receiver down-converter in tsmc standard 0.18µmCMOS technology. The operating RF bands of the proposed frequency synthesizer are between 5.15 GHz and 5.35 GHz, and the reference frequency is fixed in 10 MHz IF bands. The frequency synthesizer includes phase/frequency detector, charge pump, loop filter, the low-phase-noise and wide-tuning-range LC tank voltage-controlled-oscillator, and frequency divider。
The design targets of the frequency synthesizer are the low phase noise and the wide tuning range. We developed a VCO which is operated at 1V, having both wide tuning range and low phase noise to improve the performance of the frequency synthesizer. Finally, the circuit simulation is performed using ADS. The proposed VCO achieves a phase noise of -99.83 dBc / Hz and -117.71 dBc / Hz at the offset frequencies of 100 kHz and 1 MHz, respectively. The tuning range of 900 MHz is achieved with the control voltage from 0V to 0.85 V. The power consumptions is about 8.43 mW and the setting time is between 16 ~ 17 �酨 of the proposed frequency synthesizer.
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