Oscillation circuit, time-to-digital converter, and electronic device

A time-to-digital converter comprising:

• a plurality of oscillators that output oscillation signals having the same phase and the same frequency;
• a counter that measures periodicity of an oscillation signal outputted from any one of the plurality of oscillators;
• a plurality of phase detectors that each detect a phase of an oscillation signal outputted from a corresponding oscillator when logic of a plurality of time signals transitions;
• a plurality of count holders that hold count values of the counter when logic of the plurality of time signals transitions;
• and
• a digital signal generator that generates a plurality of digital signals corresponding to the plurality of time signals based on the count values held in the plurality of count holder and the phases detected by the plurality of phase detectors,
• wherein the plurality of oscillators comprise:
• a first oscillator having output nodes of n (n is an integer of 3 or more) stages;
• a second oscillator having output nodes of n stages;
• and
• a third oscillator having output nodes of n stages,
• an output node at an a-th stage of the first oscillator and an output node at an a-th stage of the second oscillator are connected with each other, where a is an integer of 1 or more and n or less, and
• an output node at a b-th stage of the second oscillator and an output node at a b-th stage of the third oscillator are connected with each other, where b is an integer of 1 or more and n or less different from a.

An electronic device comprising:

• a light receiver that receives a plurality of optical signals reflected at a plurality of places of an object and generates a plurality of time signals;
• a time-to-digital converter that generates a plurality of digital signals based on the plurality of time signals;
• and
• a distance measurer that measures a distance to the object based on the plurality of digital signals,
• wherein the time-to-digital converter includes:
• a plurality of oscillators that output oscillation signals having the same phase and the same frequency;
• a counter that measures periodicity of an oscillation signal outputted from any one of the plurality of oscillators;
• a phase detector that detects phases of a plurality of oscillation signals outputted from the plurality of oscillators when logic of the plurality of time signals transitions;
• and
• a digital signal generator that outputs a digital signal corresponding to the plurality of time signals based on the periodicity measured by the counter when logic of the plurality of time signals transitions and the phase detected by the phase detector,
• the plurality of oscillators comprise:
• a first oscillator having output nodes of n stages, where n is an integer of 3 or more;
• a second oscillator having output nodes of n stages;
• and
• a third oscillator having output nodes of n stages,
• an output node at an a-th stage of the first oscillator and an output node at an a-th stage of the second oscillator are connected with each other, where a is an integer of 1 or more and n or less, and
• an output node at a b-th stage of the second oscillator and an output node at a b-th stage of the third oscillator are connected with each other, where b is an integer of 1 or more and n or less different from a.