Analog-digital converter, analog-digital conversion method, and imaging device

Patent metadata

Field	Value
Publication number	US-11336855-B2
Application number	US-201915734348-A
Country	US
Kind code	B2
Filing date	May 8, 2019
Priority date	Jun 13, 2018
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

An analog-digital converter that includes voltage acquisition circuitry that acquires a voltage value of an analog signal in a settling period, calculation circuitry that calculates a predicted convergence voltage value of the analog signal based on the voltage value of the acquired analog signal, reference signal generation circuitry that generates a ramp wave reference signal based on the predicted convergence voltage value, comparison circuitry that compares the voltage value of the analog signal with the ramp wave, measurement circuitry that measures a time period from a generation of the reference signal to a time before the voltage value of the analog signal intersects with the ramp wave of the reference signal, and addition circuitry that derives a convergence voltage value of the analog signal by adding a voltage value corresponding to the measured time period and a voltage value based on the predicted convergence voltage value.

First claim

The invention claimed is:

1. An analog-digital converter comprising:
a voltage acquisition unit configured to acquire a voltage value of an analog signal in a settling period of the analog signal;
a calculation unit configured to calculate a predicted convergence voltage value of the analog signal on a basis of the voltage value of the analog signal acquired by the voltage acquisition unit;
a reference signal generation unit configured to generate a ramp wave reference signal on a basis of the predicted convergence voltage value calculated by the calculation unit;
a comparison unit configured to compare the voltage value of the analog signal with the ramp wave of the reference signal;
a measurement unit configured to measure a time period from a generation timing of the reference signal to a time before the voltage value of the analog signal intersects with the ramp wave of the reference signal; and
an addition unit configured to derive a convergence voltage value of the analog signal by adding a voltage value corresponding to the time period measured by the measurement unit and a voltage value based on the predicted convergence voltage value.

2. The analog-digital converter according to claim 1 , wherein
the reference signal generation unit maintains a first voltage value during the settling period of the analog signal, changes a voltage value at a first inclination to a voltage value based on the predicted convergence voltage value after the analog signal is converged, and then, generates a ramp wave that changes the voltage value at a second inclination smaller than the first inclination.

3. The analog-digital converter according to claim 2 , wherein
the voltage value based on the predicted convergence voltage value is a voltage value at which generation of the ramp wave that changes the voltage value at the second inclination is started.

4. The analog-digital converter according to claim 1 , wherein
the voltage acquisition unit compares the voltage value of the analog signal with the ramp wave in the settling period of the analog signal and acquires a voltage value of the analog signal when the ramp wave intersects.

5. The analog-digital converter according to claim 4 , wherein
the calculation unit calculates the predicted convergence voltage value of the analog signal by using the voltage value of the analog signal acquired by the voltage acquisition unit and a time period from start of settling of the analog signal to a time before the voltage value of the analog signal intersects with the ramp wave.

6. The analog-digital converter according to claim 1 , wherein
the calculation unit calculates the predicted convergence voltage value of the analog signal by using a fixed voltage that has been set in advance and a time period from start of settling of the analog signal to a time before the voltage value of the analog signal intersects with the fixed voltage.

7. An analog-digital conversion method for executing processing comprising:
a step of acquiring a voltage value of an analog signal in a settling period of the analog signal and calculating a predicted convergence voltage value of the analog signal on a basis of the acquired voltage value of the analog signal;
a step of generating a ramp wave reference signal on a basis of the predicted convergence voltage value of the analog signal;
a step of measuring a time period from a generation timing of the ramp wave reference signal to a time before the voltage value of the analog pixel signal intersects with the ramp wave of the reference signal; and
a step of deriving a convergence voltage value of the analog signal by adding a voltage value corresponding to the measured time period and a voltage value based on the predicted convergence voltage value.

8. The analog-digital conversion method according to claim 7 , wherein
the voltage values of the analog signal are acquired a plurality of times at equal intervals in the settling period of the analog signal.

9. The analog-digital conversion method according to claim 7 , wherein
the voltage values of the analog signal are acquired a plurality of times at unequal intervals in the settling period of the analog signal.

10. The analog-digital conversion method according to claim 7 , wherein
a gain of an analog-digital converter is adjusted according to luminance information.

11. An imaging device comprising:
a pixel array unit configured by arranging pixels including photoelectric conversion units in a matrix; and
an analog-digital converter configured to convert an analog pixel signal output from the pixel into a digital pixel signal, wherein
the analog-digital converter includes:
a voltage acquisition unit that acquires a voltage value of an analog signal in a settling period of the analog signal;
a calculation unit that calculates a predicted convergence voltage value of the analog signal on a basis of the voltage value of the analog signal acquired by the voltage acquisition unit;
a reference signal generation unit that generates a ramp wave reference signal on a basis of the predicted convergence voltage value calculated by the calculation unit;
a comparison unit that compares the voltage value of the analog signal with the ramp wave of the reference signal;
a measurement unit that measures a time period from a generation timing of the reference signal to a time before the voltage value of the analog signal intersects with the ramp wave of the reference signal; and
an addition unit that derives a convergence voltage value of the analog signal by adding a voltage value corresponding to the time period measured by the measurement unit and a voltage value based on the predicted convergence voltage value.

12. The imaging device according to claim 11 , wherein
pixel signal reading directions in an odd-number pixel column and an even-number pixel column are different from each other, and
the analog-digital converter is provided every other pixel column for each reading direction.

13. The imaging device according to claim 12 , having a structure in which at least two semiconductor substrates including a first semiconductor substrate and a second semiconductor substrate are laminated, wherein
a pixel array unit is formed on the first semiconductor substrate, and
the analog-digital converter is formed on the second semiconductor substrate.

Assignees

• Sony Semiconductor Solutions Corp
• Sony Semiconductor Solution Corp

Inventors

• NONOSHITA Yuto

Classifications

• H03M1/56 Primary

  Input signal compared with linear ramp · CPC title

• H04N25/78

  Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters · CPC title

• H04N5/378 Primary

  Electricity · mapped topic

• H04N5/37455

  Electricity · mapped topic