The inverter oscillates at a high frequency

Why do inverters oscillate at a certain frequency?

The output of each inverter is used as input for the next one. The last output is fed back to the first inverter. Because of the delay time of each stage the whole circuit spontaneously starts oscillating at a certain frequency. The frequency depends on the number of stages and the delay time of the inverters as follows

What is a ring oscillator?

A ring oscillator comprises of an odd number of CMOS inverters. The output of each inverter is used as input for the next one. The last output is fed back to the first inverter. Because of the delay time of each stage the whole circuit spontaneously starts oscillating at a certain frequency.

Which voltage oscillates with a constant stress?

The stress voltage oscillates with 1 Hz and a duty cycle of 50 % (dashed lines) and with constant stress (solid lines) have been used. The level of degradation with oscillating stress is always below constant stress and increases the lifetime.

What is a multi-level inverter?

We can realize more sophisticated multi-level inverters that can directly synthesize more intermediate levels in an output waveform, facilitating nice harmonic cancelled output content. Example: Neutral-point clamped inverters (also called ”diode clamped” multi-level inverters).