Integrated Frequency Synthesizer with an Improved LC-Tank Colpitts Voltage-Controlled Oscillator

A 5.6 GHz band frequency synthesizer with an improved LC-tank Colpitts voltage-controlled oscillator (VCO) has been designed and successfully implemented in tsmc 0.18 $\mu$m CMOS technology. The VCO is formed by two complementary nMOS and pMOS transistors for generating negative resistance to compensate the loss in the LC-tank of the VCO. A 3-bit binary weighted capacitor array is connected to the LC-tank for frequency coarse tuning and a gain boosting Colpitts technique is employed to achieve low power consumption and reduce phase noise. Under the supply voltage of1.8 V, measured results introduce that the output frequency is tuneable from 5.25 to 5.75 GHz corresponding to 9.1% with a power consumption of 17.8 mW, the phase noise at 1 MHz offset frequency from 5.6 GHz is -110.12dBc/Hz and the output power spectrum at the locked frequency of 5.606 GHz is -3.14dBm. Including pads, the chip dimension is 0.665 $(0.774\times 0.86)\mathrm{m}\mathrm{m}^{2}$.