Experimental evaluation of hot electron reliability on differential Clapp-VCO

This paper studies the hot-carrier stressed property of a series-tuned all-n core voltage controlled oscillator (VCO). A differential Clapp-VCO has been successfully implemented in the 0.13 m CMOS process and it uses a series-tuned resonator. Two single ended nMOS-core Clapp-VCOs are used to form a differential VCO by the aid of a cross-coupled nMOS pair and a transformer. The measured results show that the fresh Clapp-VCO operates from 18.8 to 22.2 GHz and hot-carrier stressed experimental data indicate that the damage increases the oscillation frequency and degrades the phase noise of oscillator. Mixed-mode simulation results are used to show the hot-carrier physics to the circuit.