A 0.4-V 1.08-mW 12-GHz high-performance VCO in 0.18-µm CMOS

A low-voltage low-power high-performance fully-integrated 0.18-μm CMOS voltage-controlled oscillator (VCO) is presented in this paper. By increasing device size of the nMOS cross-coupled pair, not only transconductance (g_m) of the MOSFET can be enhanced, but also negative conductance (-G_m) of the cross-coupled pair can be effectively boosted. Moreover, forward-body biased technique is utilized in this VCO for threshold voltage (V_t) reduction, leading to a reduced supply voltage and minimized dc power consumption. Furthermore, high-value resistors are employed between the nMOS bodies and forward-body biases to prevent the signal leakage and noise coupling. Based on these design methodologies, the fabricated 0.18-μm CMOS VCO can operate at a measured 0.4-V low supply voltage and consume 1.08-mW low core power. At this bias condition, the measured phase noise at 1-MHz offset from 12.77-GHz carrier is -110.2 dBc/Hz, and the measured tuning range is 5.75%. Compared to recently published 0.18-μm X-band CMOS VCOs, this work demonstrates the lowest supply voltage, lowest dc power dissipation, superior figure-of-merit (FOM), and better figure-of-merit including the tuning range (FOM_T).