Fully integrated low phase noise multi-band LC-tank voltage controlled oscillator with switched-capacitor resonator

This paper presents the design and implementation of a fully integrated low noise multi-band LC-tank voltage-controlled-oscillator (VCO). Multi-band operation is achieved by using switched-capacitor resonator. Additional three-bit binary weighted capacitor array is also used to extend frequency tuning range in each band. To lower phase noise, two noise filters are added and a linear varactor is adopted. Implemented in a 0.18 μm complementary-metal-oxide-semiconductor (CMOS) process, the VCO achieves a frequency tuning range covering 2.26∼2.48 GHz, 2.48∼2.78 GHz, 2.94∼3.38 GHz, and 3.45∼4.23 GHz while occupies a chip area of 0.52 mm2. With a 1.8 V power supply, it draws a current of 10.9 mA, 10.6 mA, 8.8 mA, and 6.2 mA from the lowest band to the highest band respectively. The measured phase noise is −109∼−120 dBc/Hz and −121∼−131 dBc/Hz at a 1 MHz and 2.5 MHz offset from the carrier, respectively.