JP4355747B2 - Photoelectric conversion device, photoelectric conversion system and driving method thereof - Google Patents

Description

  The present invention relates to a photoelectric conversion device, a photoelectric conversion system, and a driving method thereof, and more particularly, to a photoelectric conversion device, a photoelectric conversion system having a PN junction or a MOS transistor, and a driving method thereof.

  X-rays emitted from natural X-rays, cosmic rays, or medical devices using X-rays increase crystal defects in a PN junction that performs photoelectric conversion of the sensor.

  And the amount of defects increases with the passage of time, and when the sensor is used for a long period of time, its performance cannot be maintained.

  Conventionally, as a method for preventing the above-described deterioration, a semiconductor as described in Patent Document 1 is stored at a predetermined temperature.

  However, the technique disclosed in Patent Document 1 has a problem that storing at a predetermined temperature is not practical.

  In general, when a MOS semiconductor device is irradiated with radiation, electron-hole pairs are generated in the gate oxide film, and holes that have moved to the silicon-silicon oxide film interface are captured and accumulated at the interface. Will occur.

  As a result, it has been found that problems such as fluctuations in threshold voltage occur.

  Patent Document 2 discloses a technology in which charges generated by radiation are released by an annealing effect by setting a power supply line or a signal line to a ground potential under radiation irradiation when an element is not used. .

  However, in the technique of Patent Document 2, when the potential of the signal line connected to the photoelectric conversion element is set to the ground potential, when the photoelectric conversion operation is performed after the potential is applied, the potential of the signal line is reduced by the electrons generated by the photoelectric conversion element. The signal becomes negative and a signal cannot be obtained from the output circuit connected to the signal line. Therefore, there has been a case where imaging cannot be performed.

  The technique described in Patent Document 3 is to fix each terminal other than the photoelectric conversion element in the pixel at a certain potential for a time determined by the area occupied by the drive circuit and the photoelectric conversion element. .

  However, with the technique disclosed in Patent Document 3, the terminal potential cannot be fixed after the power supply of the imaging apparatus is turned off. Therefore, in a period in which the imaging device is not used, deterioration due to X-rays cannot be suppressed, and the electric field applied to the photoelectric conversion element is not relaxed because the photoelectric conversion element is excluded from fixing such a potential. It is not possible to prevent deterioration due to wires.

  Furthermore, in the technique described in Patent Document 4, a refresh potential different from a normal reset potential is applied to the photoelectric conversion element in order to expose holes remaining in the intrinsic semiconductor layer constituting a part of the photoelectric conversion element. It is applied to one end.

  However, in the technique disclosed in Patent Document 4, the refresh potential applies a negative potential to the other terminal of the photoelectric conversion element and applies an electric field having a non-zero magnitude to the photoelectric conversion element. It does not prevent the deterioration due to.

  Patent Document 5 discloses the following technique. That is, when all the terminals of the solid-state imaging device are in an open state, the electric field applied to the transfer electrode between the pixel portion and the CCD and the oxide film therebelow is made zero. Even when the pixel portion of the CCD is irradiated with radiation, a threshold shift and an increase in the interface state at the semiconductor / oxide interface are suppressed by ion damage.

However, this technique is not premised on prevention of deterioration due to radiation irradiation in a pixel circuit configuration of an amplification type photoelectric conversion device having an amplification MOS transistor or the like in a pixel.
JP 2002-114276 A JP-A-57-162358 JP 2001-1111020 A JP 2005-175526 A Japanese Patent Laid-Open No. 11-17160

  In a photoelectric conversion device using a photoelectric conversion element, an increase in leakage current greatly affects the quality of an output signal, and therefore it is necessary to suppress the generation of leakage current as much as possible.

  When the photoelectric conversion element is configured to include a PN junction, it has been clarified as a result of experiments that defects caused by X-rays and cosmic rays depend on the magnitude of the electric field applied to the PN junction.

  A normal photoelectric conversion device is designed to operate stably when a voltage applied to a circuit is stably supplied using a parasitic capacitance inside or outside the photoelectric conversion device. In most photoelectric conversion devices, a large external capacitance of several tens of μF is connected between terminals such as a power supply terminal and a GND terminal.

  On the other hand, analog circuits that process signals based on signal charges generated by photoelectric conversion elements are mostly constant-current biased for the purpose of stable operation, and a constant current does not depend on the magnitude of the power supply voltage. Has been supplied to.

  This constant current circuit is characterized in that its operation is stopped when the power supply voltage falls below a certain value, and the resistance value between the power supply and GND becomes very high after stopping.

  Therefore, while the photoelectric conversion device is not operating, the power consumption terminal voltage is reduced by the consumption current until a certain value of voltage is reached, but the voltage is maintained from below the voltage at which the operation of the constant current circuit stops. Tend to.

  In addition, the photoelectric conversion unit must be originally used in a high impedance state. Therefore, after the operation of the photoelectric conversion device is stopped, an electric field may remain applied to the PN junction of the photoelectric conversion unit for a very long time due to charges due to the parasitic capacitance, etc. There is also a case.

  In addition, the gate potential of the MOS transistor, which is a component of the pixel, is rarely controlled so as to be always the ground potential every time the power is turned off. In such a case, an electric field is continuously applied to the gate-drain and gate-source of the MOS transistor after the power is turned off. As a result, hot carriers are generated by the electric field applied between the gate and source (or drain) of the MOS transistor, and can be trapped in the gate oxide film to generate fixed noise, or substrate noise current can be generated. .

  Accordingly, an object of the present invention is to suppress deterioration of an output signal due to X-rays, cosmic rays, or the like when the photoelectric conversion device is not operating.

The photoelectric conversion device according to the first aspect of the present invention includes a photoelectric conversion element, a floating diffusion region, a transfer switch that transfers charges generated in the photoelectric conversion element to the floating diffusion region, and a gate in the floating diffusion region . An amplification transistor that is electrically connected and a power supply voltage is applied to the drain, one end is electrically connected to an electrical path that connects the floating diffusion region and the gate of the amplification transistor, and the other end is higher than the power supply voltage. A switching element electrically connected to a node capable of supplying a small voltage to the other end; and a control means for controlling the on / off states of the transfer switch and the switching element, the control means comprising a trigger pulse depending on the input, smaller than the power supply voltage Voltage, characterized in that on at the same time and the transfer switch element and the switching element in a state where the supplied to the other end of the switching element by the node.
The photoelectric conversion device according to the second aspect of the present invention includes a photoelectric conversion element, a floating diffusion region, a transfer switch that transfers charges generated in the photoelectric conversion element to the floating diffusion region, and a gate in the floating diffusion region. An amplifying transistor that is electrically connected and a power supply voltage is applied to the drain, one end is electrically connected to an electrical path connecting the photoelectric conversion element and the transfer switch, and the other end is electrically connected to a ground wiring And a control means for controlling respective on / off states of the transfer switch and the switch element, wherein the control means has a ground voltage applied to the switch element by the node in response to an input of a trigger pulse. The switch element and the transfer switch in a state of being supplied to the other end Characterized by turning on and child at the same time.

The photoelectric conversion device driving method according to the third aspect of the present invention includes a photoelectric conversion element, a floating diffusion region, a transfer switch that transfers charges generated in the photoelectric conversion element to the floating diffusion region, and a gate that is in the floating state. is electrically connected to the diffusion region, a driving method of a photoelectric conversion device comprising an amplifying transistor that supply voltage to the drain is applied, and a first step of receiving the trigger pulse, in the first step A second step of turning on the transfer switch element at the same time as applying a voltage smaller than the power supply voltage to an electrical path connecting the floating diffusion region and the gate of the amplification transistor in response to the received trigger pulse ; It is characterized by including.

A photoelectric conversion system driving method according to a fourth aspect of the present invention includes a photoelectric conversion element, a floating diffusion region, a transfer switch that transfers charges generated in the photoelectric conversion element to the floating diffusion region, and a gate that is in the floating state. is electrically connected to the diffusion region, an amplifying transistor supply voltage to the drain is applied, a photoelectric conversion device comprising a method of driving a photoelectric conversion system having a control device, said photoelectric conversion device a first step of receiving the door Rigaparusu from the control device, the photoelectric conversion device, according to said trigger pulses received in the first step, the floating diffusion to voltage less than the power supply voltage applied to the electrical path connecting the gate of the amplifying transistor and region At the same time, characterized in that it comprises a second step of turning on the transfer switch element.

According to the present invention, for example, it is possible to suppress deterioration of an output signal due to X-rays, cosmic rays, or the like when the photoelectric conversion device is not operating .

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  The MOS type photoelectric conversion device is configured using a PN junction and a MOS transistor arranged on a semiconductor substrate. Of these PN junctions and MOS transistors, those that are most susceptible to radiation and the like are those connected to a high impedance node that is in a floating state when not operating. The high impedance node corresponds to one terminal of the capacitor in a configuration in which the charge generated in the photoelectric conversion element is held in the capacitor. A high-impedance node in an amplifying photoelectric conversion device having a source follower in a part of a pixel circuit when converting to a voltage corresponds to an input node of the source follower. In addition, the high-impedance nodes correspond to all nodes that are electrically connected to an electrical path that passes through a process in which charges are generated by photoelectric conversion, transferred to input nodes, and converted into voltages. Therefore, the semiconductor region connected to the input node of the source follower is most susceptible to radiation and the like. Such semiconductor regions are, for example, a charge storage region of a photoelectric conversion element, a floating diffusion region (hereinafter referred to as an FD region), a source region of a transfer switch, a drain region, a source region of a reset switch, and the like.

  In the present invention, a bias supply switch for providing an external electric field applied to such a PN junction connected to such a high impedance node is preferably zero. The bias supply switch applies the semiconductor region (first semiconductor region) connected to the input node of the source follower and the semiconductor region (second semiconductor region) that forms a PN junction with the first semiconductor region. It is possible to make the external voltage to be zero. That is, this bias supply switch has a function of relaxing an external electric field applied to a PN junction or the like. The bias supply switch is turned on when the photoelectric conversion device is not operating.

  Here, the external electric field is relaxed by the bias supply switch, but it is not always necessary to make the external electric field zero. It is sufficient that the electric field is smaller than the electric field applied to the input node of the source follower during a period (at the time of operation) in which a signal by photoelectric conversion of the photoelectric conversion element such as a signal reading operation and a reset operation is used. Specifically, a description will be given of a configuration in which noise is suppressed by subtracting a noise signal in an image signal such as an offset of a MOS transistor constituting a pixel from a signal generated by photoelectric conversion. In this configuration, as a potential state of the input node of the source follower, a state in which a reset voltage is supplied to the FD region by a reset transistor and a state in which charge is read from the photoelectric conversion element to the FD region can be considered. In this pixel driving, the electric field applied by the bias supply switch may be made smaller than the external electric field applied to the first semiconductor region and the second semiconductor region in the driven pixel.

  Next, the operation of the bias supply switch will be described.

  FIG. 7 shows a schematic diagram of a photoelectric conversion system according to a preferred embodiment of the present invention. Reference numeral 700 denotes a photoelectric conversion device. Reference numeral 701 denotes a photoelectric conversion region in which a plurality of pixels are arranged. Reference numeral 702 denotes a peripheral circuit for reading out a pixel signal. The peripheral circuit 702 drives the pixel. More specifically, it is a block showing a horizontal shift register and a vertical shift register, and generates a drive end pulse when the shift operation is completed. A drive end pulse (a pulse indicating the end of processing) is received, and a pulse for operating a switch for reducing the external voltage applied to the PN junction of the pixel in the photoelectric conversion region 701 can be generated.

  Reference numeral 703 denotes a power supply circuit of the photoelectric conversion device 700. In response to receiving the driving end pulse, the photoelectric conversion device 700 performs a photoelectric conversion operation by supplying power from the power supply circuit 703 to the photoelectric conversion region 701 and the peripheral circuit 702. Reference numeral 704 denotes a control device. The power supply circuit 703 receives a control pulse from the control device 704 and supplies power. The conduction of the bias supply switch described above is controlled based on a trigger pulse supplied to cut off the power supply from the control device 704.

  During operation of the photoelectric conversion device, that is, during a period in which power is constantly supplied to the photoelectric conversion device, control is performed so that normal operation is not hindered by turning off the bias supply switch.

  In addition, the bias supply switch is configured such that an electric field relaxation function can be achieved without using a new switch in the photoelectric conversion region by diverting a switch necessary for pixel driving. Specifically, a reset switch can be used.

  Further, by controlling the logic circuit operation for driving the gate of the MOS transistor so that the gate potential becomes equal to the channel potential of the MOS transistor immediately before the power is turned off, the electric field applied to the oxide film of the MOS transistor is made zero. May be.

  Next, the relationship between the applied electric field and the amount of defects in the photoelectric conversion device will be described. FIG. 6 is a graph in which a leakage current is measured as a defect amount of a photoelectric conversion device due to an electric field applied between a gate-drain and a gate-source of a PN junction or a MOS transistor.

  In FIG. 6, the vertical axis represents the leakage current value indicating the defect amount, and the horizontal axis represents the total exposure amount of X-rays and cosmic rays. Reference symbol A is a state in which no bias is applied to the PN junction or the like, and reference symbol B is a state in which a bias is applied. It can be seen that degradation is suppressed in state A compared to state B.

  The curve described as A in FIG. 6 is based on the driving method according to the preferred embodiment of the present invention, and is a case where the electric field applied to the junction is smaller than the state of B, specifically zero. It is. It can be seen that the leakage current due to crystal defects is reduced as compared with the case of A.

  Therefore, according to the present invention, in a period in which a signal by photoelectric conversion of the photoelectric conversion element is not used, the crystal imperfection is suppressed by reducing the bias applied to the PN junction or the like described above with respect to pixel driving. Is possible.

  Hereinafter, the present invention will be described in detail with specific embodiments. However, the present invention is not limited to these embodiments, and can be modified and combined without departing from the concept of the present invention.

(First embodiment)
FIG. 1 is a circuit diagram showing a pixel portion of a photoelectric conversion device as a preferred first embodiment of the present invention. A case where electrons are used as signal charges will be described.

  In FIG. 1, reference numeral 1 denotes a photodiode that functions as a photoelectric conversion element. Reference numeral 2 denotes an amplifying transistor that constitutes a part of a source follower circuit for outputting a signal based on charges generated by photoelectric conversion with low output impedance. The amplification transistor 2 has a gate electrically connected to the output terminal of the photodiode 1 and a power supply voltage applied to the source. Reference numeral 3 denotes a selection switch for outputting the output signal of the amplification transistor 2 to a common signal line (not shown). Reference numeral 4 denotes a reset switch. The reset switch 4 is a switch element having one end electrically connected to an electrical path connecting the output end of the photodiode 1 and the gate of the amplification transistor 2 and the other end electrically connected to a node 7 described later. Reference numeral 5 denotes a bias constant current source that constitutes a part of the above-described source follower circuit. A transfer switch 6 transfers the charge of the photodiode 1 to the amplification transistor 2. Reference numeral 7 denotes a node for applying a reset voltage to the input node of the source follower circuit. The node 7 is configured to be able to switch between a power supply voltage and a voltage (for example, ground voltage) smaller than the power supply voltage, and can supply either voltage. Here, as the transfer switch 6, the reset switch 4, the selection switch 3, and the amplification transistor 2, for example, a MOS transistor can be used. The gate of the amplification transistor 2 functions as an input node of the source follower. The on / off state of the reset switch 4 and the voltage at the node 7 are controlled by a control device 704 (see FIG. 7) as a control means. In the present embodiment, the reset switch 4 is used as the bias supply switch described above.

  FIG. 8 is a cross-sectional view of a part of the pixel described in FIG. Reference numeral 801 denotes a first conductivity type (N type) semiconductor substrate, and 802 denotes a second conductivity type (P type) semiconductor region. Reference numeral 803 denotes an N-type semiconductor region. As shown in the figure, the N-type semiconductor region 803 forms a PN junction with the P-type semiconductor region 802, and constitutes the photodiode 1 serving as a photoelectric conversion element. In addition, the N-type semiconductor region 803 can be said to be a charge accumulation region because it accumulates signal charges. Reference numeral 804 denotes an N-type FD region 804. The FD region 804 is electrically connected to the gate electrode of the amplification transistor 2 (not shown). The N-type semiconductor region 803 is electrically connected to the input node of the source follower via the transfer switch 6.

  Reference numeral 805 denotes a gate of the transfer switch 6 for transferring the charge of the N-type semiconductor region 803 functioning as a charge storage region to the FD region 804. The transfer switch 6 is configured by 803, 804, and 805. Reference numeral 806 denotes an N-type source / drain region of the reset switch 4. Reference numeral 807 denotes a gate of the reset switch 4. In addition, an amplifying transistor 2, a selection switch 3 and the like (not shown) are arranged.

  Reference numeral 808 denotes a P-type semiconductor region for supplying a reference voltage (ground voltage) to the P-type semiconductor region 802. Reference numeral 809 denotes a wiring for supplying a voltage to the drain of the reset switch 4. Reference numeral 810 denotes wiring for supplying a reference voltage (ground voltage) to the P-type semiconductor region 808.

  The N-type semiconductor region 803, the transfer switch 6, and the reset switch 4 are electrically connected to the input node of the source follower, which is a higher impedance node than in FIGS. Therefore, the electric field is relaxed by the bias supply switch.

  FIG. 2 shows an example of a bias circuit that supplies a voltage to the node 7. The wiring 809 (see FIG. 8) described above is connected to the node 7. Reference numeral 11 denotes a reset power source for supplying a voltage for resetting the FD region 804 (see FIG. 8). Reference numeral 12 denotes a switch for outputting a reset voltage to the node 7. Reference numeral 13 denotes a switch for supplying a ground voltage to the node 7. In the present embodiment, the electric field relaxation voltage supplied to the drain region 806 (see FIG. 8) of the reset switch 4 is made equal to the reference voltage (ground voltage) supplied to the P-type semiconductor region 802.

  FIG. 5 is a timing chart showing the operation timing in the present embodiment.

  12 is a pulse supplied to the control terminal of the switch 12 in FIG. 2, 13 is a pulse supplied to the control terminal of the switch 13 in FIG. 2, 4 is a pulse supplied to the control terminal of the reset switch 4 in FIG. These are pulses supplied to the control terminal of the transfer switch 6 in FIG. When the control terminal receives a high level signal, they all become active and become conductive with a high pulse. In addition, the power cutoff pulse is a pulse supplied from the control device 704 to the power supply circuit 703 in FIG. This pulse cuts off the power supply to the photoelectric conversion device 700. (After the switch 12 in FIG. 2 is turned off and the switch 13 is turned on) immediately before the power supply to the photoelectric conversion device is cut off (period A in FIG. 5)), the bias supply switch (reset) Switch 4) is turned on. At this time, the circuit of FIG. 2 selects a voltage (ground voltage) equal to the reference voltage supplied to the P-type semiconductor region 802 constituting the photoelectric conversion element, and supplies it to the region 806 via the node 7. Then, control is performed so that at least a part of the period in which the reset switch 4 and the transfer switch 6 are conducted overlaps the period in which the switch 13 in FIG. 2 is conducted and the voltage is supplied to the n-type semiconductor regions 804 and 803.

  In this way, the PN junction electric field of the photodiode 1 and the electric fields of the source-well PN junction and the drain-well PN junction of the reset switch 4 and the transfer switch 6 can be relaxed or reduced to zero (FIG. 5 period B).

  Further, the function setting of a logic circuit (not shown) for driving the gates of the MOS switches of the reset switch 4 and the transfer switch 6 is set so as to become the ground potential in the period A in FIG. However, when the switch is a PMOS transistor, it is set to the power supply potential.

  According to the present embodiment, it is possible to suppress degradation of output signals due to X-rays, cosmic rays, etc. when the photoelectric conversion device is not operating. In addition, a reset switch normally used in a pixel of an amplification type photoelectric conversion device was used, and the voltage supplied to the drain of the reset switch was made to function as a bias supply switch by switching between the reset voltage and the electric field relaxation voltage. . Therefore, the above-described effect can be obtained without adding a special configuration.

  In period B, as shown in FIG. 5, a protection circuit (not shown) for protecting the pn junction may be activated so that the voltage does not fluctuate.

(Second Embodiment)
FIG. 3 is a circuit diagram showing a pixel portion of a photoelectric conversion device as a preferred second embodiment of the present invention. In this example, a bias supply switch is newly arranged in the photoelectric conversion circuit. Components similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, 8 is a bias supply switch, and 9 is a terminal for driving the bias supply switch 8. The bias supply switch 8 connects the P-type semiconductor region and the N-type semiconductor region so that the external voltage applied to the P-type semiconductor region and the N-type semiconductor region constituting the photodiode 1 can be reduced.

  The bias supply switch 8 is turned on by supplying a pulse for turning on the bias supply switch 8 to the terminal 9 before the photoelectric conversion device is deactivated. At the same time, another pulse for making the transfer switch 6 conductive is supplied to its control terminal, thereby making the transfer switch 6 conductive. As a result, the external electric field applied to the PN junction constituting the photodiode 1, between the source and well of the transfer switch 6 and the reset switch 4, and between the drain and well of the transfer switch 6 can be made zero.

  The driving in this embodiment can be performed in the same manner as in the first embodiment. That is, the pulse supplied to the terminal 9 (similar to the pulse 4 in FIG. 5) is generated based on the power cutoff pulse from the control device 704 described in FIG. The bias supply switch terminal 9 connected to the P-type semiconductor region of the photodiode 1 can be set to the same potential as the P-type semiconductor region by connecting to the well contact wiring in the pixel region.

  Also according to the present embodiment, the PN junction electric field of the photodiode 1 and the electric fields of the source-well PN junction and the drain-well PN junction of the reset switch 4 and the transfer switch 6 can be alleviated or zero. For this reason, it is possible to suppress degradation of the output signal due to X-rays, cosmic rays, etc. when the photoelectric conversion device is not operating.

(Third embodiment)
FIG. 4 is a circuit diagram showing a pixel portion of a photoelectric conversion device as a preferred third embodiment of the present invention.

  In the second embodiment, the bias supply switch 8 is electrically connected in parallel with the photodiode 1 and the transfer switch 6, whereas in the present embodiment, the bias supply switch 8 includes the gate of the amplification transistor 2, the ground wiring, Is electrically connected between.

  In this embodiment, the PN junction electric field of the photodiode 1 can be made zero by conducting the transfer switch 6 and the bias supply switch 8 at the same time immediately before the non-operation of the photoelectric conversion device. As a result, the PN junction electric field of the photodiode 1 and the electric fields of the source-well PN junction and the drain-well PN junction of the reset switch 4 and transfer switch 6 can be relaxed or reduced to zero.

  Further, the driving in this embodiment can be performed in the same manner as in the first embodiment. That is, the pulse supplied to the terminal 9 (similar to the pulse 4 in FIG. 5) is generated based on the power cutoff pulse from the control device 704 described in FIG.

  Also according to the present embodiment, the PN junction electric field of the photodiode 1 and the electric fields of the source-well PN junction and the drain-well PN junction of the reset switch 4 and the transfer switch 6 can be alleviated or zero. For this reason, it is possible to suppress degradation of the output signal due to X-rays, cosmic rays, etc. when the photoelectric conversion device is not operating.

  The present invention has been described in detail above. As described above, the present invention is not limited to these embodiments. For example, although the signal charges are described as electrons, holes can be used as signal charges by changing the conductivity type of each semiconductor region to the opposite conductivity type. Further, the configuration provided with the transfer switch has been described, but the present invention can also be applied to a configuration in which the charge storage region of the photodiode is directly connected to the input node of the source follower without a switch. In this case, it is sufficient to take a configuration that relaxes at least the electric field applied to the photodiode. That is, the effect of the present invention can be obtained by providing a switch for reducing the external voltage applied to the P-type semiconductor region and the N-type semiconductor region constituting the photodiode.

  The present invention is applicable to a photoelectric conversion device used for a camera sensor or the like.

It is a circuit diagram which shows the pixel part of the photoelectric conversion apparatus which concerns on suitable 1st Embodiment of this invention. 1 is a circuit diagram illustrating a multiplex switch according to a preferred embodiment of the present invention. It is a circuit diagram which shows the pixel part of the photoelectric conversion apparatus which concerns on suitable 2nd Embodiment of this invention. It is a circuit diagram which shows the pixel part of the photoelectric conversion apparatus which concerns on suitable 3rd Embodiment of this invention. It is a timing chart which shows the operation timing concerning a suitable embodiment of the present invention. It is a graph which shows the example which measured the defect amount of the sensor in the form of the leakage current with the electric field applied between the gate-drain of a PN junction or a MOS transistor, and a source. 1 is a schematic diagram of a photoelectric conversion system according to a preferred embodiment of the present invention. FIG. 2 is a cross-sectional view of a part of the pixel described in FIG. 1.

Explanation of symbols

700 Photoelectric conversion device

Claims (10)

A photoelectric conversion element;
Floating diffusion area,
A transfer switch for transferring the charge generated in the photoelectric conversion element to the floating diffusion region;
An amplification transistor having a gate electrically connected to the floating diffusion region and a power supply voltage applied to the drain;
One end is electrically connected to an electrical path connecting the floating diffusion region and the gate of the amplification transistor, and the other end is electrically connected to a node capable of supplying a voltage smaller than the power supply voltage to the other end. A switch element;
Control means for controlling the on / off state of each of the transfer switch and the switch element;
With
The control means, in response to input of the trigger pulse is turned on simultaneously with the transfer switch element and the switching element in a state of being supplied to the other end of the smaller voltage than the power supply voltage is the switching element by said node <br/> A photoelectric conversion device characterized by the above. The control means, in response to input of the trigger pulse, from a state in which the power supply voltage is supplied to the other end of the switching element by said node, voltage less than the power supply voltage of the switching element by said node The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is changed to a state of being supplied to the other end .   A bias circuit that selectively supplies the power supply voltage and a voltage lower than the power supply voltage to the node;
  The switch element has the other end connected to the bias circuit via the node,
  The control means is in a state where a voltage smaller than the power supply voltage is supplied to the node by the bias circuit from a state where the power supply voltage is supplied to the node by the bias circuit in response to an input of the trigger pulse. Change to
The photoelectric conversion device according to claim 2. The photoelectric conversion device according to claim 1, wherein the voltage smaller than the power supply voltage is a ground voltage.   The switch element has the other end connected to a ground terminal of the photoelectric conversion element,
  The control means changes from a state where the switch element is turned off to a state where the switch element is turned on in response to the input of the trigger pulse.
The photoelectric conversion device according to claim 4.   A photoelectric conversion element;
  Floating diffusion area,
  A transfer switch for transferring the charge generated in the photoelectric conversion element to the floating diffusion region;
  An amplification transistor having a gate electrically connected to the floating diffusion region and a power supply voltage applied to the drain;
  A switch element having one end electrically connected to an electrical path connecting the photoelectric conversion element and the transfer switch, and the other end electrically connected to a ground wiring;
  Control means for controlling the on / off state of each of the transfer switch and the switch element;
With
  The control means simultaneously turns on the switch element and the transfer switch element in response to an input of a trigger pulse in a state where a ground voltage is supplied to the other end of the switch element by the node.
A photoelectric conversion device characterized by that. A photoelectric conversion element, a floating diffusion region, a transfer switch for transferring charges generated in the photoelectric conversion device to the floating diffusion region, a gate is electrically connected to the floating diffusion region , and a power supply voltage is applied to the drain A method of driving a photoelectric conversion device comprising:
A first step of receiving a trigger pulse ;
In response to the trigger pulse received in the first step, a voltage smaller than the power supply voltage is applied to the electrical path connecting the floating diffusion region and the gate of the amplification transistor, and at the same time the transfer switch element is turned on. A second step of:
A method for driving a photoelectric conversion device comprising: The trigger pulse, the driving method of a photoelectric conversion device according to claim 7, characterized in <br/> comprises a power cutoff pulse Previous Symbol photoelectric conversion device. The trigger pulse, the driving method of a photoelectric conversion device according to claim 7, characterized in <br/> comprises a driving end pulse of the horizontal shift registers for reading out a signal from said photoelectric conversion device. A photoelectric conversion element, a floating diffusion region, a transfer switch for transferring charges generated in the photoelectric conversion device to the floating diffusion region, a gate is electrically connected to the floating diffusion region , and a power supply voltage is applied to the drain that the amplification transistor and a photoelectric conversion device comprising a method of driving a photoelectric conversion system having a control device,
The photoelectric conversion device, a first step of receiving the door Rigaparusu from said control device,
When the photoelectric conversion device, in response to said first of said trigger pulses received in step, applying a voltage less than the power supply voltage to the electric path connecting the gate of the amplifying transistor and the floating diffusion region A second step of simultaneously turning on the transfer switch element ;
A method for driving a photoelectric conversion system comprising:

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