A Flash ADC based single signal controlled VCO for the tuning of full band frequencies

• Main Authors: Ming-Long Chuang, 莊明龍
• Other Authors: Zhi-Ming Lin
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/80450521017168993235

碩士 === 國立彰化師範大學 === 積體電路設計研究所 === 99 === In this thesis, we use a flash ADC to implement a single signal control VCO for full band turning-range. All the circuit designs are based on TSMC 0.18μm CMOS standard technology model. A voltage-controlled oscillator (VCO) with a very wide frequency range is presented. The VCO needs only one control input. A 2.45 tenability PMOS varactor was designed and fabricated in a TSMC 0.18μm CMOS process for the VCO. The simulated phase noises at 1MHz offset are between -105.775 dBc/Hz and -98.561 dBc/Hz for the oscillation frequency from 3.073 GHz to 4.457 GHz. Simulated data shows that the designed VCO is suitable for ultra-wideband system applications. The second designed circuit is improved from the first designed circuit by replacing the used traditional comparator by a simple NMOS switch based comparator. The chip size and power consumption are hence reduced dramatically. The simulated phase noises at 1MHz offset of the propose VCO by the improved flash A/D converter are between -121.204 and -64.284 dBc/Hz for the oscillation frequency from 3.073 to 5.246 GHz. The total power consumption of the VCO is 36.793 mW. The obtained curves are more linear than that of the first VCO. Furthermore, we extended the design of the simple NMOS switch based comparator to a 6-bit 1-GS/s flash A/D converter. The simulated differential non-linearity (DNL) error and the integral non-linearity (INL) error are ±0.03 LSB and ±0.067 LSB, respectively. The power consumption is only 0.772mW.