Conference Paper

An LC-VCO with one octave tuning range

Radio Electron.-LECS/IMIT, R. Inst. of Technol., Stockholm, Sweden
DOI: 10.1109/ECCTD.2005.1523125 Conference: Circuit Theory and Design, 2005. Proceedings of the 2005 European Conference on, Volume: 3
Source: IEEE Xplore

ABSTRACT This paper presents a fully integrated low power and low phase-noise VCO, having a tuning range over one octave (1.2 GHz to 2.5 GHz). The architecture is fully differential and the differential tuning offers a common-mode rejection of 31 dB. The VCO is implemented in a 0.18μm CMOS process using a 1.8 V supply. The circuit, including the bias, consumes only 11.6 mW at 1.2 GHz oscillation frequency, the phase-noise is -129 dBc/Hz at 1 MHz frequency offset.

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    ABSTRACT: A 13.5-15.5 GHz low phase noise digitally controlled LC VCO, designed in a 0.25 mum BiCMOS technology, is presented in this paper. The resonant circuit of the VCO uses a high performance radio-frequency differential binary-weighted switched capacitor array (RFDSCA) to cover the 2 GHz tuning band with a continuous tuning voltage of 5 V. The RFDSCA circuit was optimized using a new automated synthesis method in order to guarantee a VCO with minimum phase noise. The VCO presents a typical phase noise of -116 dB/Hz @ 1MHz and a maximum tuning sensitivity of 165 MHz/V. The VCO core works with a voltage supply of 3 V and has a current consumption of 5 mA. The results demonstrate the feasibility of implementing and using high performance RFDSCAs as digital tuning elements at operating frequencies up to tens of gigahertz.
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    ABSTRACT: This paper deals with the design problems associated to the implementation of low power wide tuning band low phase noise LC VCOs in low cost Si-integrated technologies. For that, a VCO was developed using a low cost 0.35 mum 2-poly 4-metal standard CMOS technology. The VCO uses a radio frequency switched varactor array (RFSVA) in the tank circuit in order to decrease the influence of the varactor tuning input on the oscillator phase noise. The VCO presents a continuous tuning band from 2.76 GHz to 3.36 GHz, a single-ended output power that ranges from -12 dBm to -6 dBm and a phase noise always lower than -117 dBc/Hz at an offset frequency of 1 MHz. Moreover, the two output ports of the VCO present return losses higher than 12.7 dB in the 600 MHz tuning band. The VCO core works with a voltage supply of 1.5 V and has a current consumption of 5 mA and the output buffers draws 18 mA from a 3 V voltage supply.


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