We describe in this paper an improved ring voltage-controlled oscillator (VCO) showing a reduced phase noise while allowing an extended frequency tuning range. The phase noise improvement is obtained through the minimized contribution of tuning line noise while maintaining a rail-to-rail swing. The proposed VCO features a linear tuning characteristic yielding a constant gain over a wide range of operating frequencies. An analytical model is extracted resulting in closed-form expressions for the VCO phase noise. Employing the analytical expressions, the contributed noise and phase noise limitations are fully addressed, and all the effective factors are investigated. The VCO prototype was fabricated in a 0.35 µm CMOS process. It consumes 0.903 mW from a 3.3 V supply when running at its maximum oscillation frequency of 9.37 MHz. The measured VCO phase noise is -147.57 dBc/Hz at 1 MHz offset from the 9.37 MHz oscillation frequency, and the circuit occupies a silicon area of 0.005 mm 2 . A state-variable Matlab ® model of a timebased sensor interface has been developed including the impact of phase noise nonideality. The system-level simulations demonstrate that the PLL-based sensor interface exploiting the proposed VCO characteristics can achieve a 88.43 dB signal-to-noise ratio over a 1-kHz bandwidth.

<p>We describe in the paper a ring voltage-controlled oscillator (VCO) indicating an improved phase noise over a wide range of frequency offsets and an extended frequency/voltage tuning range. The phase noise is improved by leveraging a better linearity approach, while reducing the VCO gain and maintaining wide tuning range. The proposed VCO is a block of a time-domain comparator embedded in a monitoring and readout circuit of an industrial sensor interface. An analytical model is extracted resulting in closed-form expressions for both input-referred noise and phase noise of the VCO. Employing the analytical expressions, the contributed noise and phase noise limitations are fully addressed, and all the effective factors are investigated. The prototype of the proposed VCO was implemented and fabricated in a 0.35 µm CMOS process. The integrated VCO consumes 0.903 mW from a 3.3 V supply, when running at its maximum frequency of 9.37 MHz. The measured phase noise of the proposed VCO is -147.57 dBc/Hz at 1 MHz offset from the 9.37 MHz oscillation frequency, and the occupied silicon area of circuit is 0.005 mm².</p>

No abstract

<p>We describe in the paper a ring voltage-controlled oscillator (VCO) indicating an improved phase noise over a wide range of frequency offsets and an extended frequency/voltage tuning range. The phase noise is improved by leveraging a better linearity approach, while reducing the VCO gain and maintaining wide tuning range. The proposed VCO is a block of a time-domain comparator embedded in a monitoring and readout circuit of an industrial sensor interface. An analytical model is extracted resulting in closed-form expressions for both input-referred noise and phase noise of the VCO. Employing the analytical expressions, the contributed noise and phase noise limitations are fully addressed, and all the effective factors are investigated. The prototype of the proposed VCO was implemented and fabricated in a 0.35 µm CMOS process. The integrated VCO consumes 0.903 mW from a 3.3 V supply, when running at its maximum frequency of 9.37 MHz. The measured phase noise of the proposed VCO is -147.57 dBc/Hz at 1 MHz offset from the 9.37 MHz oscillation frequency, and the occupied silicon area of circuit is 0.005 mm².</p>

No abstract