LC-active VCO for CMOS RF transceivers

摘要

A novel fully integrated CMOS LC tank VCO is presented. The LC tanks are implemented by exploiting the active circuit 'boot-strapped inductor' (BSI), which behaves like a high-quality factor inductor. Particularly, the LC tanks have been implemented by introducing a new version of the CMOS BSI circuit, which provides better versatility and design reliability.rnIn order to verify the effectiveness of such an approach, a case study for 5-6 GHz direct-conversion multi-standard WLAN transceivers is presented. The VCO has been designed in a 0.35 μm standard CMOS technology. The new BSI exhibits a high-quality factor (higher than 25 over the all frequency range) and provides a high selectivity without introducing a relevant excess of noise, for a better spectral purity and a lower phase noise (PN) of the VCO. The overall VCO circuit consumes 9 mW. The VCO produces an oscillation in the tuning range from 4.91 to 5.93 GHz (nearly equal to 19%). The circuit exhibits a PN of - 129 dBc/Hz at 1 MHz of frequency offset from the central frequency (5.4 GHz) and a FOM equal to 189.5 dBc/Hz at 100 kHz and 194.1 dBc/Hz at 1 MHz of frequency offset, respectively.