A 3.9-4.7 GHz 0.35 mW DCO with −187.4 dBc FoM in 28nm CMOS

This paper presents an LC tank, ultra-low power CMOS digitally controlled oscillator (DCO) with resistive drain delay element designed and fabricated in 28 nm CMOS process. The implemented DCO covers 3.95 to 4.7 GHz (17% tuning range, TR) with a resolution of 300 to 500 KHz and gain variation of less than 3 % within a sub-band. Measured phase noise at 4.6 GHz is - 83, -109.5 and -130 dBc/Hz for 100 KHz, 1 MHz and 10 MHz offsets respectively. The DCO is designed to be temperature robust and allows operation within -40°C to 130°C. The DCO and output buffers consume 0.44 mA from a 0.8 V supply, for a total power of 0.35mW. The DCO active area is 0.04 mm
²
.