A wide-range VCO with an automatic frequency, amplitude and gain calibration loop

This paper presents a wide tuning range VCO with an automatic frequency, amplitude and gain calibration loop. To cover the wide tuning range, the automatic frequency calibration (AFC) loop is used. In addition, to provide the optimum Negative-Gm to the LC tank in a wide frequency range, the number of active Negative-Gm circuits is designed to be switched digitally based on the target frequency. Also, the VCO gain should be calibrated digitally to compensate for the gain variation. The VCO tuning range is 2.6 GHz, from 1.7 to 4.3 GHz, and the power consumption is 2-4 mA from a 1.8 V supply. The measured VCO phase noise is -120 dBc/Hz at 1 MHz offset.