Analog/digital conversion circuit

An analog-to-digital converter, comprising:

• an annular delay circuit that includes a plurality of delay units connected in an annular shape, each of the plurality of delay units delaying a pulse current that is input to each of the plurality of delay units;
• a current source that outputs an electric current, in accordance with an input analog signal, to first delay units, wherein the plurality of delay units includes the first delay units;
• and'
• a digital signal generation unit that generates a digital signal in accordance with a number of circulations per predetermined period of time of the pulse current circulating around the annular delay circuit,
• wherein
• the plurality of delay units includes a first plurality of delay units and a second plurality of delay units,
• the current source includes a first PMOS element and a second PMOS element,
• the first PMOS element outputs a first current to the first plurality of delay units, and
• the second PMOS element outputs a second current to the second plurality of delay units.

An analog-to-digital converter comprising:

• an annular delay circuit that includes a plurality of delay units connected in an annular shape, each of the plurality of delay units delaying a pulse current that is input to each of the plurality of delay units;
• a current source that outputs an electric current, in accordance with an input analog signal, to first delay units, wherein the plurality of delay units includes the first delay units;
• and
• a digital signal generation unit that generates a digital signal in accordance with a number of circulations per predetermined period of time of the pulse current circulating around the annular delay circuit,
• wherein
• the plurality of delay units includes a first plurality of delay units and a second plurality of delay units,
• the current source includes a PMOS element and an NMOS element,
• the PMOS element outputs a first current to the first plurality of delay units, and
• the NMOS element outputs a second current to the second plurality of delay units.

An analog-to-digital conversion method comprising:

• outputting an electric current, in accordance with an input analog signal, from a first current source to a first delay units included in a plurality of delay units included in an annular delay circuit;
• outputting the electric current, in accordance with the input analog signal, from a second current source to a second delay units included in the plurality of delay units included in the annular delay circuit and
• generating a digital signal in accordance with a number of circulations per predetermined period of time of the pulse current circulating around the annular delay circuit
• wherein each of the first delay units and each of the second delay units are not adjacent to each other.