Sensitive Devices and Phase Noise Degradation Mechanisms on all-NMOSFET RF VCO Aging

Device level reliability is introduced into simulations of an optimized all-NMOSFET, cross-coupled, radiofrequency Voltage Controlled Oscillator to trace the sensitive devices and parameters that reduce circuit performance over time. Parametric DC time dependent degradation is considered in all the devices of the circuit along with correlated flicker and thermal noise increase under hot carrier injection stress. Results show that, rather than the changes introduced by stress on DC parameters, the proposed topology is very sensitive to device level noise increase due to stress-induced traps, particularly at early stages of circuit life. This highlights the requirement of a unified simulation framework that takes into account not only DC/AC small signal degradation models but also device noise degradation in noise sensitive circuits.