A low-power, small area quadrature LC-VCO using miniature 3D solenoid shaped inductor

A low-power, small area quadrature 5 GHz LC-VCO includes 20 GHz oscillator and 1/4 divider has been fabricated using a miniature 3D solenoid shaped inductor in 90 nm CMOS. Owing to a small area and a small magnetic energy of the 3D inductor, a chip area of 2597 mum² which is 1/10 of the reported smallest LC-VCOs and 2.8 mW power consumption including the divider have been achieved without degrading a figure of merit (FOM). The phase noise was -103 dBc/Hz (@1 MHz offset) and the phase error was <1.3deg. The PLL using this LC-VCO achieved 1.2 ps rms jitter with the chip area as small as that of ring oscillators. This small area LC-VCO is suitable for low-power, low-cost wireless transceivers and high speed communication systems.