JPH09214700A - Photoelectric converter and multichip type integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the photoelectric conversion sensitivity difference of each chip in a multichip type photoelectric converter. SOLUTION: In the photoelectric converter composed by arranging many photoelectric conversion elements and arranging plural of image sensor chips 1 to n having scanning circuits for successively reading optical signals and output processing circuits for outputting read signals to the outside, each image sensor chip 1 to n makes it possible to perform more than two different settings including a set value in the gain setting of the output circuit. This setting is set through the output of a control circuit in which the pad taken out to the outside is made an input. In a multichip type integrated circuit, the output circuit which is arranged within a chip for every chip and is possible to perform a gain setting is provided. The photoelectric conversion sensitivity of the chip is compared with the photoelectric conversion sensitivity of other chips and the output level of the chip is made almost the same as the output levels of other chips.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device and a multi-chip type integrated circuit, and more particularly to a photoelectric conversion device and a multi-chip type integrated circuit in which a plurality of chips capable of equalizing photoelectric conversion efficiency for each chip are arranged.

[0002]

2. Description of the Related Art As a photoelectric conversion element, a CCD type is generally used.
There are a MOS type and an amplification type. In the CCD type, the read photoelectric conversion charges are sequentially transferred to form an image signal, while M
In the OS type, photoelectric conversion charges are accumulated in the gate of the MOS transistor, and the change in the charges is amplified and output to the outside. In this photoelectric conversion device, there are two methods that use a reduction-type optical system and an equal-magnification optical system as the difference in the optical system. In a unity-scale photoelectric conversion device, one wafer is taken out from a semiconductor crystal, and a plurality of steps are added to this wafer to form a plurality of photoelectric conversion elements and peripheral circuit chips. The chips are formed into, for example, one line. Arranged and formed as a multi-chip type line sensor.

On the other hand, a reduction-type photoelectric conversion device reduces an object to a size of one chip with a lens to obtain an image signal, and shading is performed to correct the distortion of the lens and the difference in sensitivity between photoelectric conversion elements. I was making corrections. However, as the apparatus becomes larger, it is difficult to obtain a uniform image signal only by shading correction. Therefore, in recent years, in order to reduce the size of the device, a multi-chip structure that can directly read the image signal optically has been desired. However, the size of the semiconductor wafer is generally 6 to 8 inches, and it is difficult to form a photoelectric conversion chip that can directly read, for example, 21 cm of A4 size, and it is possible to deal with it by connecting a plurality of chips in cascade. Tend to do. For example, even if the size of the semiconductor wafer is 12 inches, it is better to use multiple chips in terms of wafer usage efficiency.

[0004]

However, the photoelectric conversion of a multi-chip type / contact type image sensor in which a plurality of photoelectric conversion chips are arranged in a straight line to directly read the target image and optically becomes an equal magnification system. In the case of a device, a difference in photoelectric conversion sensitivity between individual chips becomes a problem. Therefore, it is an object of the present invention to reduce the difference in photoelectric conversion sensitivity between individual chips.

In the multi-chip type image sensor, the photoelectric conversion sensitivity difference (sensitivity variation) of each chip determines the sensitivity variation of the entire sensor. Therefore, it is desirable that the variations in sensitivity among the chips are small. Therefore,
If the variation in sensitivity caused by the variation in process processing of the semiconductor wafer can be predicted to some extent, the relative sensitivity of each chip can be made closer by adjusting the output gain of the signal processing system inside the sensor. The present invention provides one means of this method.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. A large number of photoelectric conversion elements are arranged and a scanning circuit for sequentially reading optical signals, and a read signal are externally read. In a photoelectric conversion device configured by arranging a plurality of image sensor chips each having an output processing circuit for outputting to each of the image sensor chips, the gain setting of the output circuit of each image sensor chip is different by two or more including a set value. The setting is possible, and this setting is characterized in that it is set through the output of the control circuit having the I / O pad in the chip taken out to the input as an input.

Further, in a multi-chip type integrated circuit in which a plurality of chips in which a plurality of photoelectric conversion elements are arranged are arranged, a gain setting amplifier circuit arranged in each chip and a photoelectric conversion gain of the chip are The gain of the amplifier circuit is set so that the output level of each chip is constant compared with the photoelectric conversion gain of the chip.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a conceptual block diagram of a multi-chip type photoelectric conversion device according to the present invention. 1, 2, ...
n represents a sensor chip including a photoelectric conversion element. Photon conversion elements 1-1, 2-1, ... N-1 for converting the target image into an electric signal and an instruction signal from the outside are input to each of the sensor chips 1, 2 ,. Decoder circuit 1-2, 2-2, which decodes the signal and outputs a predetermined control voltage
... n-2 and photoelectric conversion elements 1-1, 2-1, ... n-
N-3, which outputs the read signal of No. 1 at an amplification factor according to the control voltage, and the control voltage of the decoder circuit 2 and the control voltage thereof are output circuits 1-3, 2 −
Decoder output line 1 for setting gain of 3, ... n-3
-4, 2-4, ... n-4, and read scanning circuits 1-5,2-5, ... n-5 for reading out the output of each element of the photoelectric conversion element 1 in a time series in a predetermined time. , And input terminal pads 1-6, 2-6, ... N-6 for inputting an instruction signal to the decoder circuits 1-2, 2-2 ,. Therefore, each of the sensor chips 1, 2, ...
1, ... Arrange n-1 in a straight line. This arrangement means
Each photoelectric conversion element 1-1, 2-1, ... N-1 is assembled in close proximity to an adjacent element.

Next, the output circuits 1-3, 2-3, ...
Specific circuit diagrams of n-3 are shown in FIGS. FIG. 2 shows a normal output type output circuit, 21 is a MOS type or bipolar type operational amplifier, 22 and 23 are switches,
If it is a MOS type, it has decoder circuits 1-2 and 2 at the gate.
-2, ... Output circuit 1-3 by supplying control voltage from n-2 and turning on / off between the source / drain which is the main electrode
2-3, ... Controls the gain of n-3. 24-26 are resistors. Thus, the output circuits 1-3, 2-3,
The output gain GA of n-3 is the switch SW1 (22).
Is on and the switch SW2 (23) is off, the gain GA1 = {1+ (R2 + R3) / R1} (1) Also, the switch SW1 (22) is off and the switch SW
When 2 (23) is on, gain GA2 = {1 + R3 / R1} (2), and two types of gain are obtained by the control signal from the external decoder.

FIG. 3 shows a differential output type output circuit.
1 is a differential operational amplifier having one input as a signal component and the other input as a noise component, and 32 to 35 are switches,
Generally, it is composed of a MOS type and supplies four kinds of control voltages from the decoder circuits 1-2, 2-2, ..., N-2 to the gate of each switch to turn on / off between the source / drain which is the main electrode. The gain of the output circuits 1-3, 2-3, ... N-3 is controlled. 36 to 41 are resistors. The gain GB of the output circuits 1-3, 2-3, ...
When the switches SW1 (32) and SW2 (33) are on and the switches SW3 (34) and SW4 (35) are off with the resistors R1 = R4, R2 = R5, R3 = R6, the gain GB1 = (R2 + R3 ) / R1 (3) When the switches SW1 (32) and SW2 (33) are off and the switches SW3 (34) and SW4 (35) are on, the gain GB2 = R3 / (R2 + R1) (4) Therefore, the noise component is subtracted from the noise component included in the signal component, and it is possible to obtain an output signal in which only the remaining signal component is amplified with a predetermined gain.

FIG. 4 is a characteristic diagram showing the sensitivity distribution of each chip of the image sensor. (1) The photoelectric conversion sensitivity of each chip is measured in a wafer state, (2) which gain setting is to be set for each chip, and (3) the sensitivity data of each chip is used to make each chip a predetermined substrate. The gain of the output circuits 1-3, 2-3, ..., N-3 is obtained by using the designation signal supplied to the external pad as a predetermined control signal at the time of arranging it above.

Then, for example, the output circuits 1-3 and 2-
3, ... Setting the gain of n-3 to three, plus and minus, the chips in the shaded areas 11 and 22 shown in FIG. 4 are subjected to sensitivity correction and concentrated near the center of the sensitivity distribution. Then, the output level of each chip can be made almost constant.

FIG. 5 shows the state of the switches 23, 24, ...
Output circuit of a non-inverting amplifier that can obtain more than one gain 1-
It is a circuit diagram of 3,2-3, ... n-3. Further, in FIG. 6, the switches 32, 33 and the switches 34, 35 are pair-operated, respectively, and the output circuits 1-3, 2-3, ...
It is a circuit diagram of -3.

The operation when the output circuit of FIG. 5 is used for the output circuits 1-3, 2-3, ... N-3 of the multi-chip photoelectric conversion device of FIG. 1 will be described. The sensitivity of the photoelectric conversion element of each chip is determined in a wafer state by a separately provided sensitivity measuring device to determine which part of the area shown in FIG. 4 the variation in sensitivity corresponds to. The switch with the maximum gain of the output circuit of FIG. 5 that is positive is turned on, and the switch with the minimum gain of the output circuit of FIG. 5 that is negative is turned on in the region of 22 and, for example, in the region of 33. If so, the switch serving as the reference gain of the output circuit of FIG. 5 serving as the reference is turned on, and the output levels of the reference regions 33 and 44 of FIG. 4 are set. After forming the multi-chip on the substrate, the decoder is supplied with an external instruction signal to supply a predetermined control voltage to each switch to output circuits 1-3, 2 on each chip.
The output level of each chip can be made almost constant by setting the gain of -3, ..., N-3 as the gain set at the time of wafer.

Next, the operation when the differential amplifier type output circuit of FIG. 6 is used for the output circuits 1-3, 2-3, ... N-3 of the multi-chip photoelectric conversion device of FIG. Immediately after resetting the photoelectric conversion element, the noise level of the element is detected and input to the noise input terminal, then the image signal that has been photoelectrically converted to normal is input to the signal input terminal after the object is exposed for a predetermined time. Then, the noise component included in the image signal is removed, and a switch capable of setting an amplification degree that matches the output level of another chip is turned on to perform amplification to obtain the output of the image signal of the chip.

In the above embodiment, the variation of the photoelectric conversion sensitivity of each chip is divided into four, but it can be divided into two or more, and a large number of areas can be formed in accordance with the variation. Therefore, it is possible to increase the number of gains of the output circuit set according to the number of divided areas.In reality, various gains of the output circuit can be set according to the sensitivity difference of each chip measured in the wafer state. Therefore, it is possible to reduce variations in the output level of each chip.

Regarding the variation of the element output level in each chip, a shading correction circuit may be built in the output circuit, or shading correction may be performed by timely applying an AGC circuit or the like from the output as a multi-chip. You can go.

Further, in the above-mentioned embodiment, the output circuit of the normal amplification type and the differential amplification type is shown. However, an inverting amplification type output circuit may be used, and it may be combined with the output circuits of other chips. Then, if it is possible to set the gain that can reduce the variation of the output level for each chip, the difference in the phase difference and the delay time is practically no problem, so any output circuit may be used. For example, the object of the present invention can be achieved by simply providing an attenuator with a resistor and adjusting / setting the attenuation degree with a switch circuit. However, the S / N of the output of the output circuit
Is desirable, so that the amplified type is preferable.

[0019]

As described above, according to the multi-chip type photoelectric conversion device and the semiconductor integrated circuit of the present invention, the levels of the photoelectric conversion outputs of the multi-chips arranged in large numbers can be made substantially the same. , The difference in photoelectric conversion sensitivity between individual chips can be reduced.

Since the sensitivity difference of each chip is measured in the wafer state and the gain of the output circuit is set for each chip,
There is no restriction on the cascade connection of each chip, and the wafer use efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a multi-chip type photoelectric conversion device according to the present invention.

FIG. 2 is a circuit diagram of an output circuit of a photoelectric conversion device according to the present invention.

FIG. 3 is a circuit diagram of an output circuit of the photoelectric conversion device according to the present invention.

FIG. 4 is a distribution diagram of sensitivity variations of a multi-chip according to the present invention.

FIG. 5 is a circuit diagram of an output circuit of the photoelectric conversion device according to the present invention.

FIG. 6 is a circuit diagram of an output circuit of the photoelectric conversion device according to the present invention.

[Explanation of symbols]

 1-n sensor chip 1-1,2-1, ... n-1 photoelectric conversion element 1-2,2-2, ... n-2 decoder circuit 1-3,2-3, ... n-3 output Circuit 1-4, 2-4, ... n-4 Decoder output line 1-5,2-5, ... n-5 Read-out scanning circuit 1-6,2-6, ... n-6 Decoder input terminal pad m Common output line

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04N 5/335 H04N 1/40 101B

Claims (2)

[Claims] 1. A plurality of photoelectric conversion elements are arranged, and a plurality of image sensor chips each having a scanning circuit for sequentially reading optical signals and an output processing circuit for outputting the read signals are arranged. In the photoelectric conversion device configured as described above, the gain setting of the output circuit of each of the image sensor chips can be set to two or more different settings including the set value, and this setting is performed by setting the I / O pad in each chip. A photoelectric conversion device, which is set through an output of a control circuit which is an input. 2. A multi-chip type integrated circuit having a plurality of chips having a large number of photoelectric conversion elements arranged therein, wherein each chip is provided with an output circuit capable of setting a gain and the photoelectric conversion sensitivity of the chip is increased. A multi-chip type integrated circuit characterized in that the gain of the output circuit is set so that the output level of the chip is substantially the same as the output level of the other chip as compared with the photoelectric conversion sensitivity of the other chip.