A 0.2-V Three-Winding Transformer-Based DCO in 16-nm FinFET CMOS

In this brief, we introduce a 3.2-4 GHz three-winding transformer-based class-F digitally controlled oscillator (DCO) with a DC-DC booster for energy harvesting applications. A pi-model is adopted for this multi-turn transformer to analyze its impedance transformation and overall loop gain. The trifilar coil generates large passive voltage loop gain, allowing the DCO supply voltage of 0.2 V to be even lower than the threshold voltage of transistors without any performance degradation. Due to the gate/drain isolation as well as smaller voltage-dependent capacitance in advanced FinFET technology, this brief achieves very low supply frequency pushing of 38 MHz/V. The switched capacitor placed at the tertiary winding can reach very fine resolution of 1.3 kHz due to the impedance transformations and source degeneration. The bias and control voltages of nearly zero power are generated with a switched-capacitor based DC-DC converter and a ring-based non-overlapped clock generator.