JP2007202186A - Solid-state imaging apparatus and camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus in which noise can be reduced from a non-selective column, the generation of a vertical stripe can be suppressed in a bright scene, an increase in the driver size of a drain line can be prevented without necessity of charging including a floating node capacity via a resetting transistor, and a high speed operation can be secured; and to provide a camera system using the apparatus as the imaging device. <P>SOLUTION: The apparatus includes a V shift transistor 25 which is capable of supplying three or more kinds of potentials to a gate electrode of a resetting transistor 14 and in which a voltage of at least one kind of potential is a negative potential in at least the three or more kinds of potentials supplied to the gate electrode of the resetting transistor. In both precharge phase and data phase sample/hold timings, the gate potential of a resetting transistor is set to a ground potential and in other timings, the gate potential of the resetting transistor is set to a negative potential. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a camera system, and more particularly to an XY address type solid-state imaging device represented by a MOS type solid-state imaging device and a camera system using the same as an imaging device.

2. Description of the Related Art As an XY address type solid-state imaging device, for example, a MOS type solid-state imaging device, a configuration in which a unit pixel includes three transistors and a large number of unit pixels are arranged in a matrix is known.
The configuration of the unit pixel in this case is shown in FIG. As can be seen from the figure, the unit pixel 100 includes a photodiode (PD) 101, a transfer transistor 102, an amplification transistor 103, and a reset transistor 104.

  In the MOS type solid-state imaging device employing the above pixel configuration, the potential of the floating node N101 is set to a low level (hereinafter referred to as L level) from the drain line 105 through the reset transistor 104 during a period when the row is not selected. When selecting, an operation of setting the potential of the floating node N101 to a high level (hereinafter referred to as H level) is performed.

In such a MOS type solid-state imaging device, the reset transistor 104 uses a depletion type. This is because when the reset transistor 104 is turned on, the drain voltage serving as the power source of the pixel portion and the potential of the floating node 101 are made to match without variation.
Therefore, the floating node potential when the reset transistor 104 is on matches the potential level of the drain line. Specifically, as disclosed in, for example, Patent Document 1, the H level is the power supply potential VDD and the L level is 0.4 to 0.7 V (even if the L level is 0 V, for example). Good).

  Here, regarding the potential of the floating node, the selected row and the non-selected row are considered.

First, consider the operation of the selected row.
After the drain line is set to the H level, the reset transistor and the transfer transistor are sequentially turned off → on → off, and the reset phase potential and the data phase potential are output. The difference between the signals is output as an optical signal through a correlated double sampling (CDS) circuit.
In acquiring the data phase potential, if the charge of the photodiode is transferred to the floating node, the floating node potential is lowered.

Next, consider unselected rows.
Both the reset transistor and the transfer transistor remain off, and only the drain line repeats the H level and L level values.
JP 2002-51263 A

However, in the conventional MOS type solid-state imaging device, since the reset transistor adopts a depletion structure, the floating node potential rises (threshold voltage) due to the leakage current even when the reset transistor is in the off state (non-selected row). When Vth is -1V, the floating node potential is about 1V).
On the other hand, in the selected row, the floating node potential of the data phase is lower than that of the reset phase. In particular, when the amount of light is large, the voltage is greatly changed (decreased), and the potential difference from the floating node of the non-selected row becomes small.
As a result, a device that reads a potential signal from a selected row that should be set to a high potential with respect to a non-selected row increases the noise from the non-selected row because this potential difference is not clear, resulting in brighter light. There was a problem that vertical stripes occurred in the scene.

  Similarly, due to the fact that the reset transistor adopts a depletion structure, the drain wiring drive circuit can see the influence of the capacitance component of the floating node via the reset transistor. When the drain wiring is connected to all the pixels in common, it is necessary to charge not only the drain wiring capacity of all the pixels but also the floating node capacity through the reset transistor. From the point of view, there was a problem from the point of high speed.

  The object of the present invention is to reduce noise from non-selected rows, to suppress the occurrence of vertical stripes in bright scenes, and to eliminate the need for charging including the floating node capacitance via a reset transistor. An object of the present invention is to provide a solid-state imaging device capable of preventing an increase in driver size and ensuring a high-speed operation, and a camera system using this solid-state imaging device.

  In order to achieve the above object, according to a first aspect of the present invention, a unit pixel outputs a photoelectric conversion element, a transfer transistor that transfers a signal of the photoelectric conversion element to a floating node, and outputs a signal of the floating node to a signal line. A solid-state imaging device having an amplifying transistor and a reset transistor for resetting the floating node, wherein at least three types of potentials can be supplied to the gate electrode of the reset transistor and supplied to the gate electrode of the reset transistor At least one of the potentials of the first and second potentials is negative, and the gate potential of the reset transistor is set to the ground potential at the timing of both the precharge phase and the data phase sample and hold. At the timing of The gate potential of the register is set to a negative potential.

  Preferably, while the gate potential of the reset transistor of the selected pixel is set to the ground potential, the gate potential of the reset transistor of the non-selected pixel is a negative potential.

  Preferably, there is provided means capable of setting a gate potential when the reset transistor is turned from an on state to an off state from a positive high level power supply potential to a negative power supply potential through a ground level power supply potential.

  In the camera system according to the second aspect of the present invention, a unit pixel includes a photoelectric conversion element, a transfer transistor that transfers a signal of the photoelectric conversion element to a floating node, an amplification transistor that outputs a signal of the floating node to a signal line, and A solid-state imaging device having a reset transistor that resets a floating node, an optical system that guides incident light to an imaging unit of the solid-state imaging device, and a signal processing circuit that processes an output signal of the solid-state imaging device, The solid-state imaging device can supply three or more types of potentials to the gate electrode of the reset transistor, and at least one of the potentials supplied to the gate electrode of the reset transistor is a negative potential. Have some means, both precharge phase and data phase sample and hold In timing, the reset gate voltage of the transistor is set to the ground potential, the other timing gate potential of the reset transistor is set to a negative potential.

In the solid-state imaging device having the above configuration and a camera system using the same, a negative potential is applied to the gate electrode of the reset transistor when not selected.
As a result, the rise time of the common drain power supply is not influenced by the floating node capacitance via the depletion type reset transistor.
Therefore, even when a depletion type reset transistor is used, electrical connection through the reset transistor can be suppressed to a small level.
This shortens the rise time of the common drain power supply. Alternatively, the size of the drain power supply driver is reduced. As a result, high speed operation and low chip size can be realized.
In addition, since the electrical coupling through the depletion type reset transistor can be suppressed, the floating node potential of the non-selected row does not fluctuate (rise) with the potential of the common drain line.
Therefore, the difference between the floating node potentials of the selected row and the non-selected row can be clarified at the data phase sampling timing.
As a result, even when the amount of light is large, it is possible to suppress the generation of straight lines. Further, according to the present invention, the gate voltage of the reset transistor is controlled by the three values of the power supply potential, the ground potential, and the negative power supply potential.
For example, instead of directly changing the gate potential from the power supply potential to the negative power supply potential, the gate electrode voltage when turning the reset transistor from on to off is held from the power supply potential to the ground potential once, and charged / discharged to the ground potential. Is performed once, and then the potential is set to the negative power supply potential.

According to the present invention, it is possible to reduce noise from non-selected rows and to suppress the occurrence of vertical stripes in a bright scene.
In addition, there is no need to charge the floating node capacitance via the reset transistor, and it is possible to prevent an increase in the driver size of the drain line and to ensure high-speed operation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit diagram showing a configuration example of, for example, a MOS type solid-state imaging device according to an embodiment of the present invention. In the MOS type solid-state imaging device, a large number of unit pixels are arranged in a matrix, but here, for simplification of the drawing, it is drawn as a pixel array of 2 rows × 2 columns.

  In FIG. 1, the unit pixel 10 is a photoelectric conversion element. For example, in addition to the photodiode 11, the unit pixel 10 has a three-transistor configuration having three N-type MOS transistors such as a transfer transistor 12, an amplification transistor 13, and a reset transistor 14.

  In this pixel configuration, the photodiode 11 photoelectrically converts incident light into signal charges (for example, electrons) having a charge amount corresponding to the amount of light, and accumulates the signal light.

  The transfer transistor 12 is connected between the cathode of the photodiode 11 and the floating node N11, and has a gate connected to the vertical selection line 21. When the transfer transistor 12 is turned on, the signal charge accumulated in the photodiode 11 is stored. Is transferred to the floating node N11.

The amplification transistor 13 is connected between the vertical signal line 22 and the power supply Vdd, and has a gate connected to the floating node N11, and has a function of outputting the potential of the floating node N11 to the vertical signal line 22.
The reset transistor 14 has a drain (one main electrode) connected to the drain line (wiring) 23, a source (the other main electrode) connected to the floating node N11, and a gate connected to the reset line 24. Has a function to reset the potential.

In the pixel region (imaging region) in which the unit pixels 10 are arranged in a matrix, the three lines of the vertical selection line 21, the drain line 23, and the reset line 24 are in the horizontal (H) direction for each row of the pixel array. The vertical signal lines 22 are wired in the vertical (V) direction (vertical direction in the figure) for each column.
The vertical selection line 21, the drain line 23, and the reset line 24 are driven by a V shift register 25 that forms a vertical drive circuit (VDRV).

  The vertical selection line 21 and the reset line 24 are directly connected to each output terminal for outputting the vertical selection pulse T and the reset pulse R of the V shift register 25 for each row. The drain line 23 is connected to the reset voltage output terminal of the V shift register 25 via a P-type MOS transistor 26 for each row. The gate of the P-type MOS transistor 26 is grounded.

In the present embodiment, the V shift register 25 drives the reset transistor 14 with three values (may be four values or more) through the drain line 23, whereby the potential of the floating node ND11 of the selected row and the non-selected row is increased. Is provided with a potential difference to clarify the operation of the two selected rows and the non-selected rows.
For example, in the present embodiment, one of the potentials supplied to the gate electrode of the reset transistor 14 is at least a negative potential.
Further, for example, the V shift register 25 supplies at least one kind of potential among negative potentials among at least three kinds of potentials supplied to the gate electrode of the reset transistor 14.
Further, the V shift register 25 can set the gate potential when the reset transistor 14 is turned from the on state to the off state from the positive high-level power source potential to the negative power source potential via the ground level power source potential. is there.
In the present embodiment, the gate potential of the reset transistor 14 is set to the ground potential at both the precharge phase and the data phase sample and hold timing.
The V shift register 25 sets the gate potential of the reset transistor 14 of the non-selected pixel to a negative potential while the gate potential of the reset transistor 14 of the selected pixel is set to the ground potential.

  The driving operation of the reset transistor 14 will be described in detail later.

  On one side in the vertical direction (vertical direction in the figure) of the pixel region, a load transistor 27 made of an N-type MOS transistor is connected between one end of the vertical signal line 22 and the ground for each column. The load transistor 27 has a gate connected to a load line 28 and serves as a constant current source.

  On the other side in the vertical direction of the pixel region, one end (one main electrode) of a sample hold (SH) switch 29 made of an N-type MOS transistor is connected to the other end of the vertical signal line 22. The control end (gate) of the sample hold switch 29 is connected to the SH line 30.

The other end (the other main electrode) of the sample hold switch 29 is connected to the input end of a sample hold (SH) / CDS (Correlated Double Sampling) circuit 31.
The sample hold / CDS circuit 31 is a circuit that samples and holds the potential Vsig of the vertical signal line 22 and performs correlated double sampling (CDS).
Here, correlated double sampling refers to a process of sampling two voltage signals input in time series and outputting the difference between them.

A horizontal selection switch 33 composed of an N-type MOS transistor is connected between the output terminal of the sample hold / CDS circuit 31 and the horizontal signal line 32.
A horizontal scanning pulse H (H1, H2,...) Sequentially output at the time of horizontal scanning is applied to the control terminal (gate) of the horizontal selection switch 33 from the H shift register 34 constituting the horizontal drive circuit (HDRV).

When a horizontal scanning pulse H is given and the horizontal selection switch 33 is turned on, a signal subjected to correlated double sampling (CDS) in the sample hold / CDS circuit 31 is read out to the horizontal signal line 32 through the horizontal selection switch 33.
The read signal Hsig is derived as an output signal Vout from the output terminal 36 through the output amplifier 35 connected to one end of the horizontal signal line 32.

  Hereinafter, several methods for setting the drive potential (gate potential) of the reset transistor 14 and their effects in this embodiment will be described, including a comparison with a conventional circuit.

(Setting method 1)
In this method, the conventional problem can be solved by applying a negative potential to the gate electrode of the reset transistor 14 when not selected.
2 (A) to (G) and FIGS. 3 (A) to (G) are selected when the gate voltage of the reset transistor is operated with two values of VRST + (plus side) and VRST− (minus side). FIG. 5 is a diagram showing a reset transistor gate potential (RST line) V24, a transfer transistor 12 gate potential (TR line) V21, a common drain power supply potential V23, and a floating node potential VN11 in a row and a non-selected row.
2A to 2G, when the gate voltage of the reset transistor is operated at VRST + (plus side), FIGS. 3A to 3G show the gate voltage of the reset transistor according to the present embodiment as VRST−. It shows the case of operating on (minus side).
For comparison, the floating node potential in the binary operation of the reset transistor (the gate voltage of the reset transistor is VRST + (plus side) and VRST0 (zero potential)) is also shown in FIG.

In the conventional circuit, as shown in FIGS. 2A to 2G, the rise time of the common drain power supply is long due to the influence of the floating node capacitance via the depletion type reset transistor 14.
However, according to the method of the present embodiment, as shown in FIGS. 3A to 3G, even when the depletion type reset transistor 14 is used, the electrical connection through the reset transistor 14 is not caused. Can be kept small.
This shortens the rise time of the common drain power supply. Alternatively, the size of the drain power supply driver is reduced. As a result, high speed operation and low chip size can be realized.

In the conventional circuit, as shown in FIGS. 2A to 2G, the floating node potential of the non-selected row is affected by the common drain power supply due to the influence of leakage through the depletion type reset transistor. It increases in the sampling time of the data phase, and acts in a direction that the potential difference between the selected row and the non-selected row becomes smaller.
However, according to the method according to the present embodiment, as shown in FIGS. 3A to 3G, the electrical coupling through the depletion type reset transistor 14 can be suppressed, so that the floating of the non-selected row is performed. The node potential does not change (rise) with the potential of the common drain line.
Therefore, the difference between the floating node potentials of the selected row and the non-selected row can be clarified at the data phase sampling timing.
As a result, even when the amount of light is large, it is possible to suppress the generation of straight lines.

(Setting method 2)
In this method, the function of controlling the three values of the power supply potential (for example, 3 V), the ground potential (0 V), and the negative power supply potential (for example, −1 V) as the gate voltage of the reset transistor 14 is mounted. Can be solved.

As described above, in the MOS type solid-state imaging device, the depletion type is used as the reset transistor. Thereby, there is an advantage that the reset variation can be reduced when the reset transistor is turned on.
On the other hand, at this time, firstly, the difference between the floating node potentials of the unselected row and the selected row is not clear, and secondly, from the standpoint of the common drain power supply, there are problems of high speed and chip size.
Therefore, in the present embodiment, the L level potential of the reset transistor in the non-selected row is set to a negative potential.

In order to supply a negative potential to the MOS type solid-state imaging device, there are two methods: a method of supplying from an external power source and a method of generating a negative potential in an internal circuit.
Compared to the amplitude of the gate of the conventional reset transistor (the amplitude of the power supply potential and the ground potential), when using the negative potential according to the above method, the amplitude is increased, so that the charge amount of charge / discharge of the circuit is large. There is a risk that the potential generation circuit (or power supply) may be burdened.
For this reason, in a circuit that internally generates a negative potential, it is necessary to increase the charge supply capability by the amplitude, which increases the chip size.
In particular, in the case of a negative power source generated by an internal circuit, circuit noise is superimposed on the generated potential. Since the gate of the reset transistor 14 to which the negative power supply potential is supplied is capacitively coupled to the floating node N11, fluctuations in the negative power supply potential appear as sensor noise as they are.

  In order to solve these problems, in the present embodiment, the gate voltage of the reset transistor 14 is controlled to three values of a power supply potential (for example, 3 V), a ground potential (0 V), and a negative power supply potential (for example, −1 V). Equipped with functions.

For example, as shown in FIGS. 4A to 4G, regarding the problem of the charge supply capability, the load on the negative power supply generation circuit can be reduced by driving the gate potential of the reset transistor 14 in three values.
Until now, the voltage of the gate electrode when turning on and off the reset transistor directly changes the gate potential from the power supply potential to the negative power supply potential.
By enabling the ternary driving function according to the present embodiment, a function of holding the power supply potential once to the ground potential, charging / discharging the ground potential once, and then setting the potential to the negative power supply potential is mounted. This can solve the previous problem.
In brief, when the power supply potential is 3 V, the ground potential is 0 V, and the negative power supply potential is −1 V, the following effects can be obtained.
When the voltage changes directly from the conventional power supply potential to the negative power supply potential, if the circuit capacity is C [F], the charge / discharge charge amount is Q = C (V1−V2) = 4C, and the negative power supply generation circuit Will incur a 4C burden.
On the other hand, when passing through the ground potential once, since the potential difference necessary for the negative power generation circuit to pull out is 1V, the charge / discharge charge amount is 1C, which is reduced to a quarter of the burden of the conventional method.

In addition, in the case of a negative power source generated by an internal circuit, circuit noise is superimposed on the generated potential. Since the gate of the reset transistor 14 to which the negative power supply potential is supplied is capacitively coupled to the floating node N11, variations in the negative power supply potential appear as sensor noise as they are.
By the way, the potential fluctuation of the ground potential is small with respect to the fluctuation of the negative power supply potential generated in the internal circuit.
Using this, for example, as shown in FIGS. 5A to 5G, in the selected row, the gate electrode potential of the reset transistor is set to the ground potential during the precharge phase and the data phase sample and hold timing period. Fixed (the gate potential of the reset transistor in the non-selected row is always fixed to a negative potential).
As a result, the number of changes to the negative potential is reduced, so that not only the negative charge supply burden is reduced, but also the influence of noise due to the fluctuation of the capacitive coupling of the floating node potential due to the potential fluctuation of the negative power generation circuit can be suppressed. .
In addition, the reset gate is set to 0V for the selected row and negative potential for the non-selected row, so that there is always a significant difference in the floating node potential between the selected row and the non-selected row, preventing vertical stripes even in bright scenes. can do.

  Furthermore, as shown, for example, in FIGS. 6 (A)-(G), the method associated with FIGS. 4 (A)-(G) and the method associated with FIGS. 5 (A)-(G), When the reset transistor 14 is turned off, the combined drive of the method of setting a negative potential via the ground level (0) and the method of setting the sample and hold timing to the ground level has two more effects at the same time. can get.

  Next, an operation example of the MOS type solid-state imaging device according to this embodiment having the above-described configuration will be described. Here, description will be made by paying attention to the lower left pixel in FIG. 1. As an example, the gate voltage of the reset transistor 14 is set to a power supply potential (for example, 3V), a ground potential (0V), and a negative power supply potential (for example, −1V). A case where a method of controlling the three values is adopted will be described as an example.

  First, when not selected, the potential of the floating node N11 is 0.5V. At this time, the power supply voltage dd, for example, 3.0 V is output from the V shift register 25 as the reset voltage B1, and the potential of the drain line 23 is also the power supply voltage Vdd.

  A load signal to be applied to the load line 28 is set to 1.0 V, for example, and then an H level reset signal R1 is output from the V shift register 25. Then, since the reset transistor 14 becomes conductive, the floating node N11 is connected to the drain line 23 through the reset transistor 14, and the potential thereof is reset to an H level determined by the channel voltage of the reset transistor 14, for example, 2.5V. As a result, the gate potential of the amplification transistor 13 is also 2.5V.

  The potential Vsig1 of the vertical signal line 22 is determined by the highest gate voltage among the amplification transistors of the plurality of pixels connected to the vertical signal line 22, and as a result, the potential Vsig1 of the vertical signal line 22 is determined by the potential of the floating node N11. . Specifically, the amplification transistor 13 forms a source follower with the load transistor 27, and the output voltage appears on the vertical signal line 22 as the pixel potential Vsig1. The potential Vsig1 at this time becomes a reset level voltage. This reset level voltage is input to the sample hold / CDS circuit 31 through the sample hold switch 29.

  Next, the vertical selection pulse T1 output from the V shift register 25 is set to H level. Then, the transfer transistor 12 becomes conductive, photoelectrically converted by the photodiode 11, and the accumulated signal charge (electrons in this example) is transferred (read) to the floating node N11. As a result, the gate potential of the amplification transistor 13 changes in the negative direction according to the signal amount of the signal charge read from the photodiode 11 to the floating node N11, and the potential Vsig1 of the vertical signal line 22 also changes accordingly. To do.

  The potential Vsig1 at this time becomes the voltage of the original signal level. This signal level voltage is input to the sample hold / CDS circuit 31 through the sample hold switch 29. Then, the sample hold / CDS circuit 31 takes a difference between the voltage at the previous reset level and the voltage at the current signal level, and performs processing for holding this differential voltage.

Next, the reset voltage B1 output from the V shift register 25 is set to 0V. At this time, the reset voltage B1 ′ applied to the pixel 10 through the drain line 23 is determined not by 0V but by the channel voltage of the P-type MOS transistor, and is, for example, 0.5V.
In this state, when the H level reset signal R1 is output from the V shift register 25, the reset transistor 14 is turned on, so that the floating node N11 is connected to the drain line 23 through the reset transistor 14, and the potential is the potential of the drain line 23, That is, it becomes 0.5 V, and the pixel 10 returns to the non-selected state.
At this time, when the reset transistor 14 is turned on and off through the reset line 24, the gate potential of the reset transistor 14 is not changed directly from the power supply potential 3V to the negative power supply potential, but once from the power supply potential. After maintaining the ground potential at 0V and charging / discharging the ground potential once, the negative power supply potential is set to the potential −1V. As a result, the potential difference required for the negative power supply generation circuit to be pulled out becomes 1 V, the charge / discharge charge amount is reduced, and the burden on the circuit is reduced.

  In this non-selected state, the potential of the floating node N11 is 0.5V instead of 0V, so that electrons are prevented from leaking to the photodiode 11 through the transfer transistor 12. Here, the potential of the floating node N 11 becomes 0.5 V due to the action of the P-type MOS transistor 26 connected between the reset voltage output terminal of the V shift register 25 and the drain line 23.

Through the series of operations described above, all pixels in the first row are driven simultaneously, and signals for one row are simultaneously held (stored) in the sample hold / CDS circuit 31. Thereafter, a photoelectric conversion (exposure) and photoelectron accumulation period starts in the photodiode 11.
During this photoelectron accumulation period, the H shift register 34 starts horizontal scanning operation, and sequentially outputs horizontal scanning pulses H1, H2,. Accordingly, the horizontal selection switch 33 is sequentially turned on, and the signals held in the sample hold / CDS circuit 31 are sequentially led to the horizontal signal line 32.

  Next, if the same operation is performed on the pixels in the second row, the pixel signals of the pixels in the second row are read out. Thereafter, the pixel signals of all rows can be read out by sequentially performing vertical scanning with the V shift register 25, and the signals of all pixels can be read out by sequentially performing horizontal scanning with the H shift register 34 for each row.

As described above, in the three-transistor MOS solid-state imaging device in which the unit pixel 10 includes the transfer transistor 12, the amplification transistor 13, and the reset transistor 14, the gate voltage of the reset transistor 14 is set to the power supply potential (for example, 3V) and the ground potential (for example). 0V) and the negative power supply potential (for example, -1V), the noise is controlled from non-selected rows and the occurrence of vertical stripes in a bright scene can be suppressed.
In addition, there is no need to charge the floating node capacitance via the reset transistor, and it is possible to prevent an increase in the driver size of the drain line and to ensure high-speed operation.

FIG. 7 is a block diagram showing an outline of the configuration of the camera system according to the present invention.
The camera system 40 drives the imaging device 41, an optical system that guides incident light to the pixel region of the imaging device 41, for example, a lens 42 that forms incident light (image light) on the imaging surface, and the imaging device 41. And a signal processing circuit 44 that processes an output signal of the imaging device 41, and the like.

  In this camera system, as the imaging device 41, the solid-state imaging device according to the above-described embodiment, that is, the unit pixel 10 has a transfer transistor 12, an amplification transistor 13, and a reset transistor 14 in addition to the photodiode 11, and One of the potentials supplied to the gate electrode of the reset transistor is at least a negative potential, or a MOS type solid-state imaging device having a configuration capable of supplying three or more types of potentials to the gate electrode of the reset transistor is used.

  The drive circuit 43 has a timing generator (not shown) for generating various timing signals including a start pulse and a clock pulse for driving the V shift register 25 and the H shift register 34 in FIG. In order to realize the described driving, the imaging device (MOS type solid-state imaging device) 41 is driven. The signal processing circuit 44 performs various signal processing on the output signal Vout of the MOS type solid-state imaging device 41 and outputs it as a video signal.

  Thus, according to the present camera system, by using the MOS solid-state imaging device according to the above-described embodiment as the imaging device 41, the MOS solid-state imaging device can reduce noise from a non-selected row, and a bright scene In addition, it is possible to suppress the occurrence of vertical streaks in the circuit, and since there is no need to charge the floating node capacity via the reset transistor, the increase in the drain line driver size can be prevented, and high-speed operation can be ensured.・ High-quality captured images with low power consumption and low noise can be obtained.

1 is a circuit diagram illustrating a configuration example of, for example, a MOS solid-state imaging device according to an embodiment of the present invention. It is a figure which shows the gate potential of the reset transistor in the selected row and the non-selected row, the gate potential of the transfer transistor, the common drain power supply potential, and the floating node potential when the gate voltage of the reset transistor is operated at VRST + (plus side). . Reset transistor gate potential, transfer transistor gate potential, common drain power supply in selected row and non-selected row when the gate voltage of the reset transistor is operated with two values of VRST + (plus side) and VRST− (minus side) It is a figure which shows an electric potential and a floating node electric potential. It is a figure for demonstrating the method of carrying out the ternary drive of the gate voltage of a reset transistor. It is a figure for demonstrating the method of ternary driving the gate voltage of a reset transistor, Comprising: It is a figure for demonstrating the method of setting the sample hold of a precharge phase and a data phase to a ground potential, utilizing a negative potential. is there. It is a figure for demonstrating the method which combined the method of setting a negative electric potential via a ground level when turning off a reset transistor, and the method of setting a sample hold timing to a ground level. It is a block diagram which shows an example of a structure of the camera system which concerns on this invention. It is a block diagram of the unit pixel for demonstrating the subject of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Unit pixel, 11 ... Photodiode, 12 ... Transfer transistor, 13 ... Amplification transistor, 14 ... Reset transistor, 22 ... Vertical signal line, 23 ... Drain line, 24 ... Reset line, 25 ... V shift register, 26 ... P MOS transistor 31... Sample hold / CDS circuit 32. Horizontal signal line 34 H shift register

Claims (6)

A solid-state imaging device in which a unit pixel includes a photoelectric conversion element, a transfer transistor that transfers a signal of the photoelectric conversion element to a floating node, an amplification transistor that outputs the signal of the floating node to a signal line, and a reset transistor that resets the floating node Because
Means for supplying three or more potentials to the gate electrode of the reset transistor, wherein at least one of the potentials supplied to the gate electrode of the reset transistor is a negative potential. ,
A solid-state imaging device in which the gate potential of the reset transistor is set to a ground potential at both the precharge phase and the data phase sample and hold timing, and the gate potential of the reset transistor is set to a negative potential at other timings. The solid-state imaging device according to claim 1, wherein the gate potential of the reset transistor of the non-selected pixel is a negative potential during a period in which the gate potential of the reset transistor of the selected pixel is set to the ground potential. The solid according to claim 1, further comprising means capable of setting a gate potential when the reset transistor is turned from an on state to an off state from a positive high-level power supply potential to a negative power supply potential via a ground level power supply potential. Imaging device. A solid-state imaging device in which a unit pixel includes a photoelectric conversion element, a transfer transistor that transfers a signal of the photoelectric conversion element to a floating node, an amplification transistor that outputs a signal of the floating node to a signal line, and a reset transistor that resets the floating node When,
An optical system for guiding incident light to the imaging unit of the solid-state imaging device;
A signal processing circuit for processing an output signal of the solid-state imaging device,
The solid-state imaging device is
Means for supplying three or more potentials to the gate electrode of the reset transistor, wherein at least one of the potentials supplied to the gate electrode of the reset transistor is a negative potential. ,
The camera system in which the gate potential of the reset transistor is set to a ground potential at both the precharge phase and the data phase sample and hold timing, and the gate potential of the reset transistor is set to a negative potential at other timings. The camera system according to claim 4, wherein the gate potential of the reset transistor of the non-selected pixel is a negative potential during a period in which the gate potential of the reset transistor of the selected pixel is set to the ground potential. 6. The camera according to claim 4, further comprising means capable of setting a gate potential when changing the reset transistor from an on state to an off state from a positive high level power source potential to a negative power source potential through a ground level power source potential. system.

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