A 5.56 GHz Single Core Digitally-Controlled Oscillator With Direct Fine Tuning Steps of 2.85 kHz

As nanotech gets smaller and decreases in size, it is aiding in giving rise to better and more robust smart devices. At the heart of most of these smart devices is some sort of an oscillator. The better the oscillator design and the higher its performance potential, the more robust, more complex, and smarter these devices can become. This work presents a single core DCO (digitally-controlled oscillator) that can step through fine tuning step sizes of as low as 2.85 kHz at frequency of 5.56 GHz without the need of using either dithering, dual -gm pair, inductive switching, expensive FinFET, silicon-on-insulator (SOI), or frequency division (pushing the sub-micron technology of regular 40 nm CMOS to another level). This small resolution is achieved by using fixed MOM caps (highest Q available capacitors in 40 nm TSMC kit). The DCO had 4 banksets on the drain with 16 banks each and 1 bankset on the source with 20 banks. The DCO spanned frequency of 5.41 GHz (all banks closed) to 6.75 GHz (all banks open) with a tuning range of 22.04%. The phase noise (PN) performance of the DCO was 114 dBc/Hz (@ 1MHz offset) at frequency of 6.75 GHz, and had FoM of -181 dBc/Hz @ 1 MHz offset; DCO power consumption was 10 mW.