Inverter and ring oscillator based on inverter

A ring oscillator comprising:

• a plurality of inverters arranged in a ring, each inverter comprising an inverter input and an inverter output, the inverter output of each inverter in the ring is coupled to the inverter input of the respective next inverter in the ring;
• and
• wherein at least one inverter of the plurality of inverters further comprises:
• a first NMOS transistor comprising a first gate terminal coupled to the respective inverter input, a first drain terminal coupled to the respective inverter output, and a first source terminal;
• and
• a second NMOS transistor comprising a second gate terminal, a second drain terminal and a second source terminal, wherein the second source terminal is coupled to the first drain terminal.

A phase locked loop circuit comprising:

• a ring oscillator comprising:
• a plurality of inverters arranged in a ring, each inverter comprising an inverter input and an inverter output, the inverter output of each inverter in the ring is coupled to the inverter input of the respective next inverter in the ring;
• and
• wherein at least one inverter of the plurality of inverters further comprises:
• a first NMOS transistor comprising a first gate terminal coupled to the respective inverter input, a first drain terminal coupled to the respective inverter output, and a first source terminal;
• and
• a second NMOS transistor comprising a second gate terminal, a second drain terminal and a second source terminal, wherein the second source terminal is coupled to the first drain terminal;
• and
• a phase comparator configured to determine a difference between a phase of a signal at an output of the ring oscillator and a phase of a reference signal, the phase compensator configured to provide a control signal based on the difference to control at least one of a frequency and a phase of the ring oscillator.