Solid-state imaging element, imaging apparatus, and control method of solid-state imaging element with improved reading speed of pixel signals
It is intended to improve reading speed of pixel signals in a solid-state imaging element provided with an ADC. A plurality of pixels are arrayed in a pixel block. A drive circuit drives the pixel block to output a plurality of pixel signals at the same time. A comparator successively selects the plurality of pixel signals and compares the selected pixel signals and a predetermined reference signal. A control section generates a control signal for updating the predetermined reference signal on the basis of comparison results of the comparator. A reference signal update section updates the predetermined reference signal according to the control signal.
1. A solid-state imaging apparatus comprising:
a pixel area comprising:
a plurality of pixels arranged in rows and columns; and
a plurality of column lines, each of the plurality of column lines being coupled to a respective column of pixels of the plurality of pixels; and
circuitry comprising a plurality of successive approximation analog-to-digital converters (SARADC), at least one of the plurality of SARADCs being coupled to at least two column lines of the plurality of column lines, wherein the at least one of the plurality of SARADCs comprises a comparator configured to compare a reference signal with a pixel signal provided to the comparator through one of the at least two column lines, and wherein the comparator comprises:
a first transistor configured to receive a first pixel signal;
a second transistor configured to receive a second pixel signal; and
a third transistor configured to receive the reference signal.
2. The solid-state imaging apparatus of claim 1 , wherein each of the plurality of SARADCs is coupled to at least two respective column lines of the plurality of column lines.
3. The solid-state imaging apparatus of claim 1 , wherein each of the plurality of pixels comprises at least one photodiode.
4. The solid-state imaging apparatus of claim 1 , wherein the circuitry is configured to drive at least two rows of pixels of the plurality of pixels simultaneously.
5. The solid-state imaging apparatus of claim 4 , wherein the circuitry is configured to drive all the rows of pixels of the plurality of pixels simultaneously.
6. The solid-state imaging apparatus of claim 1 , wherein the circuitry is configured to vary the reference signal over time.
7. The solid-state imaging apparatus of claim 6 , wherein the circuitry is configured to vary, during a predefined time slot, the reference signal until a least significant bit (LSB) is generated based on the pixel signal.
8. The solid-state imaging apparatus of claim 1 , wherein the comparator comprises a selection section configured to select the pixel signal between:
a first pixel signal provided to the comparator through a first column line of the at least two column lines, and
a second pixel signal provided to the comparator through a second column line of the at least two column lines.
9. The solid-state imaging apparatus of claim 1 , wherein the comparator further comprises:
a first switch coupled to a source and a drain of the first transistor; and
a second switch coupled to a source and a drain of the second transistor.
10. The solid-state imaging apparatus of claim 9 , wherein the comparator further comprises:
a third switch coupled to the first switch; and
a fourth switch coupled to the second switch.
11. The solid-state imaging apparatus of claim 10 , wherein the first switch is configured to receive a first control signal and the third switch is configured to receive an inversion signal of the first control signal; and
the second switch is configured to receive a second control signal and the fourth switch is configured to receive an inversion signal of the second control signal.
12. The solid-state imaging apparatus of claim 1 , wherein the comparator comprises a first output signal line and a second output signal line.
13. The solid-state imaging apparatus of claim 12 , wherein the first output signal line is coupled to a first node between the first transistor and a power source; and the second signal line is coupled to a second node between the third transistor and the power source.
14. The solid-state imaging apparatus of claim 12 , wherein the first output signal line is coupled to a first node between the first transistor and a ground; and the second signal line is coupled to a second node between the third transistor and the ground.
15. The solid-state imaging apparatus of claim 1 , wherein the plurality of SARADCs comprises a first SARADC and a second SARADC, wherein the circuitry is configured to provide a first reference signal to the first SARADC and a second reference signal to the second SARADC, the second reference signal being different from the first reference signal.
16. A solid-state imaging apparatus comprising:
a pixel area comprising a plurality of pixel lines comprising:
a first pixel line coupled to a first plurality of pixels and a second pixel line coupled to a second plurality of pixels; and
circuitry comprising a successive approximation analog-to-digital converter (SARADC) coupled to the first pixel line and to the second pixel line, wherein the SARADC comprises a comparator configured to compare a reference signal with a pixel signal provided to the comparator through one of the first pixel line and the second pixel line, and wherein the comparator comprises:
a first transistor configured to receive a first pixel signal;
a second transistor configured to receive a second pixel signal; and
a third transistor configured to receive the reference signal.
17. The solid-state imaging apparatus of claim 16 , wherein:
the first pixel line is a first column line and the first plurality of pixels is a first column of pixels, and
the second pixel line is a second column line and the second plurality of pixels is a second column of pixels.
18. The solid-state imaging apparatus of claim 16 , wherein each of the first and second plurality of pixels comprises at least one photodiode.
19. The solid-state imaging apparatus of claim 16 , wherein the first and second plurality of pixels are arranged in rows of pixels, and wherein the circuitry is configured to drive at least two of the rows of pixels simultaneously.
20. The solid-state imaging apparatus of claim 16 , wherein the circuitry is configured to drive all the rows of pixels simultaneously.
21. The solid-state imaging apparatus of claim 16 , wherein the circuitry is configured to vary the reference signal over time.
22. The solid-state imaging apparatus of claim 21 , wherein the circuitry is configured to vary, during a predefined time slot, the reference signal until a least significant bit (LSB) is generated based on the pixel signal.
23. The solid-state imaging apparatus of claim 16 , wherein the comparator comprises a selection section configured to select the pixel signal between:
a first pixel signal provided to the comparator through the first pixel line, and
a second pixel signal provided to the comparator through the second pixel line.
24. The solid-state imaging apparatus of claim 16 , wherein the comparator further comprises:
a first switch coupled to a source and a drain of the first transistor; and
a second switch coupled to a source and a drain of the second transistor.
25. The solid-state imaging apparatus of claim 24 , wherein the comparator further comprises:
a third switch coupled to the first switch; and
a fourth switch coupled to the second switch.
26. The solid-state imaging apparatus of claim 25 , wherein the first switch is configured to receive a first control signal and the third switch is configured to receive an inversion signal of the first control signal; and
the second switch is configured to receive a second control signal and the fourth switch is configured to receive an inversion signal of the second control signal.
27. The solid-state imaging apparatus of claim 16 , wherein the comparator includes a first output signal line and a second output signal line.
28. The solid-state imaging apparatus of claim 27 , wherein the first output signal line is coupled to a first node between the first transistor and a power source; and the second signal line is coupled to a second node between the third transistor and the power source.
29. The solid-state imaging apparatus of claim 27 , wherein the first output signal line is coupled to a first node between the first transistor and a ground level; and the second signal line is coupled to a second node between the third transistor and the ground level.
30. The solid-state imaging apparatus of claim 16 , wherein the SARADC is a first SARADC, and wherein:
the plurality of pixel lines further comprise a third pixel line coupled to a third plurality of pixels and a fourth pixel line coupled to a fourth plurality of pixels,
the circuitry further comprises a second SARADC coupled to the third pixel line and to the fourth pixel line, and
the circuitry is configured to provide a first reference signal to the first SARADC and a second reference signal to the second SARADC, the second reference signal being different from the first reference signal.