Analysis and Design of Digital Controlled Low-Phase-Noise CMOS LC_VCO

A fully integrated cross-coupled digital controlled LC tank voltage-controlled oscillator (LC-VCO) is proposed to achieve a low phase noise, the LC_VCO receives the external n-bits control words FTRIM to control the capacitors switches and change LC-tank shunt capacitors, thus changes the tuning range of LC_VCO. Meanwhile the LC_VCO receives the external k-bits control words KVCO to control the varactors switches and led to the change of voltage control sensitivity. The digital controlled oscillator based on the proposed topology is simulated and verified by the standard SMIC 0.13um CMOS technology. The simulation gave a phase noise of -125.3dBc/Hz at 1 MHz, the entire circuit consumes the current is only 2.98mA under a 1.2 V supply.