Low power $380\ \mu \mathrm{W}$ Energy Efficient 1.8 GHz Digitally Controlled Oscillator for IoT Applications

The design of a low power LC-tank DCO for IEEE 802.11ah Internet-of-Things (IoT) applications is developed and presented herein. To address the stringent power consumption requirements of IoT devices, reduction of the supply voltage (VDD) down to 0.4 V is proposed. In a SoC mostly composed by digital blocks, VDD reduction is advantageous though presenting great challenge for the analog and AMS blocks design. The main contribution of the proposed methodology is to minimize the negative impact of VDD reduction on phase noise performance of the DCO. In this work, the DCO is designed using the Unified Current-Control Model (UICM) and operates from 1.8 to 1.86 GHz. At the maximum frequency and at a VDD of only 0.395 V, the power consumption is $380\ \mu \mathrm{W}$ and the phase noise is −119.3 dBc/Hz at 1 MHz. The circuit occupies an area of 0.46 mm2 in 40 nm CMOS process.