JP2003250088A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device having a detection circuit capable of simultaneously realizing a high sensitivity and a wide dynamic range. <P>SOLUTION: The sensor device includes a sensor array in which infrared ray sensors are arrayed and the detection circuit connected to an output signal line y of the sensor array. The detection circuit includes a capacitor C2 having a charging circuit which is selectively driven, a sense amplifier circuit which detects and amplifies a change in sensor current flowing to the output signal line y, a current-to-voltage conversion circuit which converts the output current from the sense amplifier circuit into a voltage, a discharging circuit which is controlled by the output voltage of the current-to-voltage conversion circuit to discharge the capacitor C2, and an output circuit which outputs the terminal voltage of the capacitor C2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor device represented by an infrared sensor and the like, and more particularly to a signal detection circuit thereof.

[0002]

2. Description of the Related Art An image sensor having a two-dimensional array of infrared sensors has an advantage that it can be used even at night, but it is inferior in sensitivity and dynamic range to an image sensor using visible light. For example, when applied to a surveillance camera or the like, a NETD (Noise of about 1K)
Equivalent Temperature Di
and a dynamic range of about 30K are required. Therefore, by increasing the linearity of the sensor output,
Development of infrared sensors with higher sensitivity and wider dynamic range is required.

An infrared sensor array is constructed by arranging a plurality of infrared sensors on a silicon substrate. The infrared sensor includes an infrared absorption section and a diode (usually configured as a series connection of a plurality of diodes) as a thermoelectric conversion element that converts the heat generated in the infrared absorption section into an electric signal. In the case of a bolometer type uncooled infrared sensor device, each sensor is kept hollow to effectively provide the heat generated to the diode. Such hollow support structures are made by micromachining technology.

Infrared rays radiated from an object are condensed by an optical lens installed in front of the sensor to raise the temperature of the diode of each sensor. As the optical lens, a material having a high infrared transmission efficiency, for example, a Ge film is used. For example, when a Ge lens having a transmittance of 90% and an F value of 1.0 at a wavelength of 8-12 μm is used, the surface temperature of the object is 1
The temperature rise of the diode when K changes is about 1 × 10
^-3K . The diode is driven by a constant current source so that a constant current flows. The current density J through the diode as a function of temperature T is J = Js ( ^{eqv / kT-}
1), Js = T3 ^{+ [gamma] / 2} * exp (-Eg / kT). Here, k is a Boltzmann constant, Eg is a band gap of silicon, and γ is a predetermined constant.

As the temperature of the diode rises, the voltage drop Vf of the diode decreases. Now, the voltage drop Vf for the 1K rise of 8 diodes connected in series is about 2
It is assumed that it is 0 mV / K. At this time, for example, when the surface temperature of the object rises by 30K, the voltage drop becomes 0.618 m.
A potential difference of V occurs. An infrared image is detected by detecting this potential difference and outputting it as a sensor output.

However, in the conventional bolometer type uncooled infrared sensor, the characteristics of the sensor output with respect to the temperature change of the diode are not linear, and it is difficult to achieve both high sensitivity and wide dynamic range.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sensor device having a detection circuit capable of achieving both high sensitivity and a wide dynamic range.

[0008]

The present invention takes the following means in order to achieve the above object.

A first aspect of the present invention is to provide a sensor array in which sensors for detecting a physical change amount or a chemical change amount and outputting an electric signal are arranged, a sense amplifier circuit for amplifying the electric signal, A current transfer circuit comprising a first stage and a second stage, wherein a first current appearing in the first stage based on the amplified electric signal is supplied to the second stage by a second current.
A current transfer circuit for transferring the current as a current, a current-voltage conversion circuit for converting the second current into a first voltage, a capacitor charged with an electric charge, and a first load element connected to the capacitor. And discharging the electric charge of the capacitor or charging the capacitor via the first load element based on the first voltage.
And a discharge circuit for outputting a voltage change of the capacitor based on the discharge or charge by the first discharge / charge circuit.

The current transfer circuit transfers, transfers, as a second current to the second stage, a first current appearing in the first stage as a second current based on the amplified electric signal.
It has functions such as output and generation.

A second aspect of the present invention provides a sensor array in which sensors for detecting a physical change amount or a chemical change amount and outputting an electric signal are arranged, a capacitor, and the electric signal of the sensor array. A first discharging / charging circuit for driving a capacitor based on a driving voltage to discharge a charge of the capacitor or charging the capacitor with a charge; and a second discharge for charging the capacitor with a charge or discharging a charge from the capacitor. / Charging circuit, the capacitor and the second
Control circuit for controlling the drive voltage based on the potential of the node between the discharge / charge circuit and the output circuit for outputting the voltage change of the capacitor discharged or charged by the first discharge / charge circuit. And a sensor device.

According to such a structure, it is possible to realize a sensor device having a detection circuit capable of achieving both high sensitivity and a wide dynamic range.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, constituent elements having substantially the same functions and configurations are designated by the same reference numerals, and redundant description will be given only when necessary.

FIG. 1 is a diagram showing a main configuration of a sensor device (bolometer type uncooled infrared sensor) according to the present embodiment. The unit infrared sensor 1 of the sensor array has a diode array in which a plurality of diodes as thermoelectric conversion elements are connected in series, and this is arranged at the intersection of the matrix selection lines x and y. The anode of the diode is connected to one selection line (driving line) x, and the cathode is connected to the other selection line (output signal line) y.

FIG. 2 is a plan view showing the structure of one pixel region of the sensor array portion of the infrared sensor device according to this embodiment. FIG. 3 is a sectional view taken along the line III-III ′ of FIG. As shown in the figure, in the sensor array, an infrared sensor 1 supported in a hollow state with a void 20 is formed on a single crystal silicon substrate 10 as a semiconductor substrate. The infrared sensor 1 has a thermoelectric conversion element formed of a plurality of diodes 18 formed in a silicon layer and connected in series, and a silicon oxide film 19a and a silicon nitride film 19b formed above the thermoelectric conversion element via an interlayer insulating film. It has an infrared absorption layer 19 made of a laminated film.

The hollow infrared sensor 1 is fixed to a substrate 10 in which row and column selection lines 12 and 13 (corresponding to the drive line x and the output signal line y in FIG. 1) for selecting pixels are embedded. It is surrounded by the frame body portion 11 in the state. Then, the frame portion 11 and the infrared sensor 1 are connected to each other to connect the infrared sensor 1
In order to support the hollow part of the support beam 14,15
Are formed so as to float from the substrate 1. The support beams 14 and 15 are embedded with signal wirings 16 and 17 for connecting the terminals of the diode of the infrared sensor 1 to the matrix selection lines 12 and 13 of the frame body 11.

FIG. 1 shows a measuring circuit focusing on one infrared sensor 1 of the above cell array. This measuring circuit is also formed on the same silicon substrate as the sensor array and around the sensor array. . The driver 2 that drives the drive line x is configured by a two-stage CMOS inverter to which the “V register” that is the output of the vertical scanning register is input. The detection circuit 3 that detects a change in the sensor current flowing through the output signal line y has a storage capacitor C2 that is periodically precharged. One end of the capacitor C2 is grounded, and the other end N4 has a charging NM for selectively charging.
The OS transistor MN5 is connected. Detection circuit 3
When the sensor 1 is selected, the sensor output is detected by discharging the charge of the storage capacitor C2 according to the output of the sensor 1.

At the first stage of the detection circuit 3, a current line sensing type sense amplifier circuit 31 is provided. The sense amplifier circuit 31 includes a load NMO connected to the output signal line y.
It has an S transistor MN0, a sense NMOS transistor MN1 for detecting a voltage obtained at the terminal N1 of the output signal line y by the load NMOS transistor MN0, and the like. The source of the load NMOS transistor MN0 is grounded, a fixed bias GL1 is applied to the gate thereof, and a constant current I0 in the pentode region flows. Therefore, the voltage drop Vf of the diode of the sensor 1 is applied to the terminal N1.
A voltage that changes corresponding to is obtained. A sense NMOS transistor MN1 having a gate connected to the terminal N1 via a coupling capacitor C1 is provided.

A current source load PMOS transistor MP1 whose gate and drain are connected is provided between the drain of the NMOS transistor MN1 and the power supply terminal.
The source of the NMOS transistor MN1 is connected to the terminal HAMP to which the control voltage is selectively applied via the NMOS transistor MN2. During the sensing operation, the terminal HAMP is grounded. A terminal N is provided between the gate terminal N2 and the drain of the sense NMOS transistor MN1.
An NMOS transistor MN3 for initializing 2 to a predetermined level for pentode operation is provided.

In order to convert the output current I1 of the sense amplifier circuit 31 into a voltage, a current-voltage conversion circuit 32 including a PMOS transistor MP2 which constitutes a current mirror circuit together with the PMOS transistor MP1 is provided. Two NMOS transistors MN11 and MN are provided between the drain of the PMOS transistor MP2 and the ground terminal.
12 are connected. One NMOS transistor M
A fixed bias voltage GL3 is applied to the gate of N11, and the voltage of the terminal N4 of the storage capacitor C2 is fed back to the gate of the other NMOS transistor MN12.

The PMOS transistor MP2 has a P
A current I reflecting the current I1 of the MOS transistor MP1
2 is output. If the dimensions of the PMOS transistors MP1 and MP2 are the same, then I1 = I2. This current I2
Are shunted as I21 and I22 according to the conductances of the NMOS transistors MN11 and MN12, respectively. The output terminal N of the current-voltage conversion circuit 32 is
In 3, the voltage drawn by the current drawing capability of the NMOS transistors MN11 and MN12 and the output current I2 of the PMOS transistor MP2 can be obtained.

The output terminal N of the current-voltage conversion circuit 32
NMOS transistor MN13 whose gate is connected to 3
Is a discharge circuit 3 for discharging the charge of the storage capacitor C2.
Make up three. The source of the NMOS transistor MN13 is grounded via the resistor R, and the drain is connected to the terminal N4 of the storage capacitor C2 via the selection switch NMOS transistor MN4.

An output circuit 34 is provided to take out the voltage of the terminal N4 of the capacitor C2. Output circuit 34
Has a gate having a selection switch NMOS transistor MN6
NMOS transistor M connected to terminal N4 via
N8 and an NMOS transistor M connected in series with it
It is a voltage follower composed of N9. The reset NMOS transistor MN7 is connected to the gate of the NMOS transistor MN8.

The operation of the present sensor device can be roughly divided into two. One is a current I2 corresponding to the current I1.
The current I3 discharged by the discharge circuit 33 is linearly controlled by the voltage generated on the basis of the resistance R. The other is a feedback system control for eliminating the influence of the leak current generated in the charging circuit for charging the storage capacitor C2. Hereinafter, focusing on these two points, the operation of the sensor device will be described with reference to FIG.

FIG. 4 shows a measurement operation waveform of two-dimensional scanning when the sensor array is composed of m × n sensors. Δt0 is the output “V register” of the vertical scanning register
Is a total scanning period of m drive lines x, and each drive line x
For each scanning cycle Δt1, the horizontal scanning read is performed by the output “H register” of the horizontal scanning register to select n output signal lines.

Specifically, the operation will be described by paying attention to the drive line x and the signal line y one by one in FIG. 1. First, at time t0 at the beginning of scanning, the terminals VRST and HAMP become high level, and the NMOS. The storage capacitor C2 is charged (reset) to the voltage VRS by the transistor NM5. The reset operation of the capacitor C2 is repeated every vertical scanning cycle. After the resetting of the capacitor C2 is completed, the terminals HFB and HA are held at the high level.
SEL1 goes high (time t1). This allows
Sense NMO via NMOS transistor MN2
The source of the S transistor MN1 is boosted and the drain thereof is boosted to near the power supply voltage VDD, and at the same time, the gate terminal N2 is also charged by the NMOS transistor MN3.

Then, HAMP, VFB, HASEL1
Returns to the low level, the NMOS transistors MN2 and M
When N3 is turned off and the terminal N2 is initially set to a predetermined voltage and floats,
The source of the S transistor MN1 is also opened (time t2). That is, the sense NMOS transistor MN1
Is set to a biased state where the gate is floating and pentode operation is possible, after which the sensor 1 is driven.

First, the terminals VRST and HASEL2 become high level (time t3), and after a short delay, the "V register" becomes high level, and at the same time the terminal HASEL1 also becomes high level (time t4). As a result, the storage capacitor C2 is charged again, and at the same time, the discharging NMOS transistor M
N13 is connected to the terminal N4 of the storage capacitor C2, and the source of the sensing NMOS transistor MN1 is grounded and activated. When the NMOS transistor MN1 is activated, the charging operation of the capacitor C2 is completed.

The output current I0 of the sensor 1 is substantially constant because the NMOS transistor MN0 is biased in the pentode region. Diode voltage drop nΔ caused by temperature rise ΔTd of diode due to incident infrared rays
Vf is a sensing NMOS via a coupling capacitor C1
It is applied to the gate terminal N2 of the transistor MN1. When the initial setting voltage of the gate terminal N2 is Vref, this becomes Vref + nΔVf due to the sensor output.

Then, in the sense amplifier circuit 31, the current flowing through the sense NMOS transistor MN1 changes to I1 + ΔI1 due to the voltage change of the gate terminal N2. Unlike the conventional circuit, the drain of the sensing NMOS transistor MN1 has the current source load PMOS transistor MP1. Therefore, in this sense amplifier circuit 31, the drain of the NMOS transistor MN1 can perform class A amplification operation within the range of the power supply voltage. And voltage-current conversion with excellent linearity is performed.

In the current-voltage conversion circuit 32, the current I2 + ΔI2 reflecting the current of the PMOS transistor MP1 is supplied by the PMOS transistor MP2. Therefore, this current and the NMOS transistor MN1 are supplied to the terminal N3.
1, the voltage V2 determined by the resistance of MN12 is obtained. Then, the voltage V2 drives the NMOS transistor MN13 of the discharge circuit 33, and the charge of the storage capacitor C2 is turned on via the NMOS transistor MN4.
It is discharged through the OS transistor MN13 and the resistor R.

The discharge current I3 of the discharge circuit 33 is supplied to the terminal N3.
Voltage V (N3) and the voltage of the terminal N4 of the capacitor C2. This discharge current I3 and capacitor C2
5A and 5B show the dependence of the time change of the charge change amount (that is, the discharge charge amount) ΔQ on the resistance R. FIG. 5A shows the case where the resistance R is absent or sufficiently small, and FIG. 5B shows the case where the resistance R is sufficiently large. If there is no resistance R or it is small enough, V
The change of the discharge current I3 with (N3) as a parameter is shown in FIG.
A waveform as shown in FIG. In this case, the charge amount changes ΔQ1 and ΔQ2 of the capacitor C2 between the times t4 and t5 during which the sensor 1 is driven are obtained by integrating the discharge current I3 from the times t4 to t5, but as shown in the figure, they are not always linear. It doesn't.

On the other hand, when the resistance R is sufficiently large, the discharge current I3 changes linearly as shown in FIG. 5B, and the voltage V (N3) at the terminal N3 and the charge amount change. Δ
Q also becomes almost linear. Further, the voltage V3 at the terminal N4 is V
Since 3 = VRS−ΔQ / C, the voltage at the terminal N4 also changes linearly. This terminal voltage is "V register"
Becomes low level and then becomes high level, the signal is taken out from the output circuit 34 to the output terminal Sout via the NMOS transistor MN6.

The "H register" is the output of the horizontal scanning register, which sequentially goes high as shown in FIG.
The output of the book output signal line y is scanned and output. In the latter half of each horizontal scanning period Δt4, the horizontal scanning reset signal HRST becomes high level and the NMOS transistor M
The input terminal of the output circuit 34 is reset by N7.

The reason why the dynamic range is improved by this embodiment is as follows. NMO for sense
In the case of this embodiment, the S transistor MN1 does not directly discharge the capacitor C2, but the current source load PMOS transistor MP1 is connected to form the sense amplifier circuit 31. Therefore, in the sense amplifier circuit 31, voltage-current conversion with good linearity is performed without being affected by the terminal voltage of the capacitor C2. The output current I1 is
After being copied as I2 by the current mirror, MN
It is converted into the gate voltage Vg of the MN 13 by the current-voltage conversion circuit 32 using 11, and thereby the discharge circuit 33.
Is driven. The discharge current I3 of the discharge circuit 33 is determined by the input voltage and the resistance R, but is given by Vg = V2 (terminal voltage of N3) −R × I3. Therefore, R has a function of suppressing the current I3 that rapidly increases with the increase of the potential of V2 (proportional to I2), which also results in improving the linearity. Therefore, the output voltage changes linearly in a wide input voltage range, and the dynamic range is improved.

Further, in the sensor device according to this embodiment,
The discharge current I3 is linearly controlled by the voltage obtained by the current-voltage conversion circuit 32 using the current mirror and the resistor R. Therefore, the linearity of the sensor output can be improved without increasing the capacitance of the capacitor C2, and high sensitivity can be realized.

Further, in the sensor device according to this embodiment, the NMOS transistor M of the current-voltage conversion circuit 32 is used.
The NMOS transistor MN12 provided in parallel with N11 functions to accelerate the voltage drop at the terminal N4. That is, terminal N
When the voltage of 4 drops, the NMOS transistor MN12
Conductance decreases, increasing the voltage of the terminal N3. This increases the discharge current of the capacitor C2 by the discharge circuit 33, and acts to accelerate the voltage drop at the terminal N4. This allows the capacitor C to be used even in the high input voltage range.
The terminal N4 of No. 2 can be lowered to a sufficiently low level, and the dynamic range can be expanded.

In FIG. 1, when the voltage of the terminal N4 of the capacitor C2 drops, the leakage current of the charging NMOS transistor MN5 increases, which is the terminal N.
The voltage drop of 4 is prevented. However, in the sensor device according to the present embodiment, the capacitor C2 is operated as follows.
Can be sufficiently discharged to reduce the potential. That is, the NMOS transistor M of the current-voltage conversion circuit 32
The NMOS transistor MN12 provided in parallel with N11 functions to accelerate the voltage drop at the terminal N4. When the voltage of the terminal N4 decreases, the conductance of the NMOS transistor MN12 decreases and the voltage of the terminal N3 increases. This increases the discharge current of the capacitor C2 by the discharge circuit 33, and acts to accelerate the voltage drop at the terminal N4. As a result, the terminal N4 of the capacitor C2 can be lowered to a sufficiently low level even in a high input voltage region,
The dynamic range is expanded.

FIG. 6 shows a comparative example of the sensor device according to the present embodiment, and shows a main part configuration of a conventional typical sensor device (measurement circuit focusing on one infrared sensor 1 of the sensor array). It is the figure shown. The sensor 1 has a plurality of diodes connected in series as described above, and this is arranged at the intersection of the matrix selection lines x and y. The anode of the diode is connected to one selection line (driving line) x, and the cathode is connected to the other selection line (output signal line) y.

The driver 2 driven by the output "V register" of the vertical scanning register is connected to the drive line x, and the current is supplied to the sensor 1 by the PMOS transistor MP102 at the time of selection. Terminal N1 of output signal line y
Is grounded through the NMOS transistor MN0, and the terminal N1 is connected to the gate of the sensing NMOS transistor MN1 of the detection circuit 3 through the coupling capacitor C1. The sense NMOS transistor MN1 performs an operation of discharging the charge of the storage capacitor C2 according to the sensor output. The voltage change due to the discharge of the storage capacitor C2 is taken out as an output Sout by a voltage follower composed of NMOS transistors MN8 and MN9.

Briefly explaining the measurement operation, prior to selection of the sensor 1, the storage capacitor C2 is charged with a constant voltage VRS via the NMOS transistor MN5. Further, the NMOS transistors MN3 and MN2 are turned on, and a positive voltage is applied to the source of the sensing NMOS transistor MN1 from the terminal HAMP to sense NMO.
After charging the gate of the S transistor MN1, the gate is made floating. Specifically, NMO for sense
The S-transistor MN1 is initialized so as to be gate-biased under the condition of operating a pentode.

When the sensor 1 is selected in this state, the gate voltage Vg of the sensing NMOS transistor MN1 changes corresponding to the voltage drop Vf of the diode. NMO
When the S-transistor MN4 is turned on, the sense NMO is
The storage capacitor 2 is discharged by the S-transistor MN1, and the potential drops. Therefore, temperature can be measured by reading the voltage due to the electric charge remaining in the capacitor C2 through the selection transistor MN6 and the voltage follower.

FIG. 7 shows the input voltage Vin of the sensing NMOS transistor MN1 of the conventional sensor device shown in FIG.
And the relationship between the output voltage Vout of the storage capacitor C2 and the solid line. The slope of the voltage-current curve in the figure is the temperature sensitivity. As is clear from the figure, the sensitivity is low in the region where the temperature change is small (the region where the input voltage Vin is small). Further, when the input voltage becomes high, the output voltage Vo
Since ut is saturated, the sensitivity becomes low. Therefore, the dynamic range becomes small. Preferably, as shown by the broken line in FIG. 7, it is preferable that constant sensitivity be obtained in a wide input voltage range.

When the above-described conventional sensor device and the sensor device according to the present embodiment are compared, there are two major differences in structure.

The first point is the presence or absence of a mechanism for controlling the discharge of the storage capacitor C2 to be linear so as to achieve high sensitivity and a wide dynamic range of the sensor device.

That is, in the conventional sensor device, high sensitivity cannot be obtained in a wide voltage range as described above. The main cause is that the storage NMOS transistor MN1 directly discharges the storage capacitor C2. As described above, the sensing NMOS transistor MN1 operates as a pentode, and its discharge current I1 is determined by the square of the input gate voltage. Since the change in the voltage drop Vf of the diode is at most several 100 μV and the change in the input gate voltage is small, one sense NMOS transistor MN1 is used.
Then, a large change in the discharge current I1 cannot be obtained.

On the other hand, in the sensor device according to this embodiment, as described above, the sensing NMOS transistor MN is used.
1 does not directly discharge the capacitor C2, but the current source load PM
The OS transistor MP1 is connected to form the sense amplifier circuit 31. The output current I1 is converted into a voltage by the current-voltage conversion circuit 32 using a current mirror, and the discharge circuit 33 is driven by this. Therefore, the output voltage can be changed linearly in a wide input voltage range, and a wide dynamic range can be secured.

In order to realize high sensitivity and wide dynamic range in the conventional sensor device, it is conceivable to adjust the capacitance of the storage capacitor C2.
That is, if the capacitance of the storage capacitor C2 is reduced,
Large sensitivity can be obtained in a small input voltage range.
However, in this case, the output voltage is easily saturated when the input voltage becomes high. Further, if the capacitance of the storage capacitor C2 is increased, the output voltage can be prevented from being saturated up to the high input voltage range, but on the contrary, the sensitivity in the small input voltage range is sacrificed.

On the other hand, in the sensor device according to this embodiment, the current-voltage conversion circuit 32 using the current mirror is used.
The discharge current I depends on the voltage obtained by
3 is linearly controlled. Therefore, the linearity of the sensor output can be improved without increasing the capacity of the capacitor C2, and high sensitivity and a wide dynamic range can be realized.

The second point is the presence / absence of a feedback system for eliminating the influence of the leak current generated in the charging circuit for charging the storage capacitor C2. That is,
In the conventional measurement circuit, when the potential of the storage capacitor C2 drops due to discharge, the leak current of the NMOS transistor MN5 increases, and this leak current prevents the potential drop of the storage capacitor C2. This causes the output voltage saturation value in the high input voltage region to not become sufficiently low.

On the other hand, in the sensor device according to this embodiment, when the voltage of the terminal N4 of the capacitor C2 decreases, the leakage current of the charging NMOS transistor MN5 increases, which prevents the voltage decrease of the terminal N4. Is the same as before. However, in the sensor device according to the present embodiment, as described above, when the voltage of the terminal N4 decreases due to the influence of the leak current, the conductance of the NMOS transistor MN12 decreases and the feedback system increases the voltage of the terminal N3. ing. Due to the action of this feedback system, the discharge current of the capacitor C2 by the discharge circuit 33 is increased and the voltage drop at the terminal N4 is accelerated. As a result, the terminal N4 of the capacitor C2 can be lowered to a sufficiently low level even in a high input voltage region, and the dynamic range can be expanded.

Next, FIG. 8 shows an embodiment in which the configuration of the sense amplifier circuit 31 in FIG. 1 is modified. In this embodiment, a bipolar transistor is used for the sense amplifier circuit 31. Output the base and collector signal line y
Npn transistor Q1 connected to the
Represents the sensor current I0 obtained on the output signal line y by the voltage V0.
Act as a diode to convert to. An npn transistor Q2 forming a current mirror circuit with this transistor Q1 and a current source PMOS connected to its collector
The voltage V0 is converted into a current I1 by the transistor MP1.

The voltage-current conversion circuit 32 has an NMOS transistor MN14 whose gate is driven by the collector of the transistor Q2, a current source PMOS transistor MP2 provided on the drain side of the NMOS transistor MN14, and a source side provided as a load element. NMOS transistor MN11,
With MN12.

In this embodiment, the diode temperature rise ΔTd due to the incidence of infrared rays is eliminated without using the constant current source NMOS transistor MN0 as in the previous embodiment.
The change in the diode current I0 in the sensor 1 caused by the above is directly taken out as a change in the voltage of the transistor Q1, and thus as a change in the collector-emitter current I1 of the transistor Q2. Therefore, it is not necessary to detect the voltage drop of the diode of the sensor 1, and therefore it is not necessary to connect the diodes in series. As a result, the sensor 1
The area can be reduced, and the power supply voltage of the driver 2 can be lowered to reduce power consumption.

Sense amplifier circuit 31 of this embodiment
Also outputs the output current I1 in response to the change in the output current I0. Then, this current I1 is converted into a voltage by the current-voltage conversion circuit 32 as in the previous embodiment, and the discharge circuit 33 is controlled. Also in the circuit of this embodiment, the change in the output current I0 and the change in the charge amount of the capacitor C2 have good linearity for the same reason as in the previous embodiments.

The bipolar transistors Q1 and Q2 used in the sense amplifier circuit 31 of this embodiment are provided on the same substrate 10 as the sensor array, as shown in FIG.
It can be formed by the structure of (b). FIG. 8 includes an n-type collector layer 21, a p-type base layer 22 formed in the n-type collector layer 21, and an n + -type emitter layer 23 formed in the p-type base layer 22. 2 shows a vertical transistor that is used. FIG. 9 shows a lateral transistor in which an n + type collector layer 25 and an n + type emitter layer 26 are formed in a p type base layer 24.

In the above embodiments, the uncooled infrared sensor array has been described as the sensor array, but the circuit of the present invention can be applied to various other sensors. For example, FIG. 10 shows DN detecting nucleic acid such as DNA.
The A sensor is shown. DNA sensor (DNA chip)
Is used to detect the nucleotide sequence of a gene or the like, and its structure is described in detail in, for example, US Pat. No. 5,776,672, US Pat. No. 5,972,692 and the like.

Each cell includes a probe electrode 101 and its 3
It has a counter electrode 102 facing the side and a reference electrode 103 facing the remaining one side. The sensor arranged in the solution can fix the voltage between the probe electrode 101 and the reference electrode 103 by applying a voltage to the counter electrode 102 and the reference electrode 103 by the potentiostat 104.
On the probe electrode 101, various types of DNA probes are attached in a single-stranded state, and when the sample DNA is dropped, it forms a double strand only when it has the same base sequence as the DNA probe. Utilizing that, the sample DN
A will be determined.

Specifically, as shown in FIG. 11, the sample D is attached to the DNA probe attached on the probe electrode 101.
When NA is dropped, the sample DNA is hybridized with the DNA probe to form a double strand. Further addition of certain intercalating agent molecules here will bind them to the duplex. In this state, the vertical scanning register 105 and the horizontal scanning register 106
When a voltage is applied to the probe electrode 101 of the cell selected by, the electrons of the intercalating agent flow into the probe electrode due to an electrochemical reaction, and a current flows.

As a result, the output current flows through the signal line y selected by the horizontal scanning register 106 among the matrix signal lines x and y in FIG. This output current is converted to the data line D
By detecting with the detection circuit 107 connected to L,
The sample DNA can be determined. The output current drawn from the data line DL is the current I1 shown in FIG. 1 or 8, and the detection circuit 107 has the same configuration as the detection circuit 3 described in FIG. 1 or FIG. Will be possible.

In the above embodiment, the sensor 1
It has been described that an infrared image is generated by discharging the electric charge charged in the capacitor C2 based on the voltage drop generated in the above and reading the voltage due to the electric charge remaining in the capacitor C2. On the other hand, the initial state of the capacitor C2 is set to zero, the capacitor C2 is charged based on the voltage drop generated in the sensor 1, and the voltage due to the charges accumulated in the capacitor C2 is read out to form an infrared image. It can also be generated. in this case,
The configuration is similar to that of the sensor device according to the above embodiment, and control is performed to make the levels of the GND potential and the reset potential of the capacitor C2 negative. With this control, for example, in FIG. 1, the current I3 controlled by opening / closing the NMOS transistor 13 flows in the opposite direction to the case of the above-described embodiment, and a sensor device having a charging structure can be realized.

The present invention has been described above based on the embodiments. However, within the scope of the idea of the present invention, those skilled in the art can come up with various modifications and modifications, and the modifications and modifications. It is understood that the examples also belong to the scope of the present invention. For example, as in the following (1) and (2), various modifications can be made without changing the gist of the invention.

Further, the respective embodiments may be combined as appropriate as much as possible, in which case the combined effects can be obtained. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effect described in the section of the effect of the invention can be solved. When at least one of the above is obtained, the configuration in which this constituent element is deleted can be extracted as the invention.

[0064]

As described above, according to the present invention, it is possible to realize a sensor device having a detection circuit capable of achieving both high sensitivity and a wide dynamic range.

[Brief description of drawings]

FIG. 1 is a diagram showing a measurement circuit of an infrared sensor according to an embodiment of the present invention.

FIG. 2 is a plan view showing a unit sensor cell of the infrared sensor according to the same embodiment.

FIG. 3 is a sectional view taken along the line III-III ′ of FIG.

FIG. 4 is an operation timing chart of the measurement circuit according to the same embodiment.

5A and 5B are diagrams for explaining characteristics of the discharge circuit according to the embodiment.

FIG. 6 is a diagram showing a measurement circuit of an infrared sensor that is a comparative example with the sensor device according to the present embodiment.

7 is a diagram showing an output voltage-input voltage characteristic in the infrared sensor shown in FIG.

FIG. 8 is a diagram showing a measurement circuit according to another embodiment of the present invention.

9A is a diagram showing a structure of a bipolar transistor used in the measurement circuit shown in FIG. FIG. 9B is a diagram showing another structure of the bipolar transistor used in the measurement circuit shown in FIG.

FIG. 10 is a diagram showing a configuration of a DNA sensor to which the sensor device according to the embodiment of the present invention is applied.

11 is a diagram for explaining the operation principle of the DNA sensor shown in FIG.

[Explanation of symbols]

1 ... Infrared sensor 2 ... driver 3 ... Detection circuit 10 ... Single crystal silicon substrate 12, 13 ... Row and column selection lines 14, 15 ... Support beam 16, 17 ... Signal wiring 18 ... Diode 19a ... Silicon oxide film 19b ... Silicon nitride film 19 ... Infrared absorbing layer 20 ... void 21, 25 ... Collector layer 22, 24 ... Base layer 23, 26 ... Type emitter layer 31 ... Sense amplifier circuit 32 ... Current-voltage conversion circuit 33 ... Discharge circuit 34 ... Output circuit 90 ... Transmittance 101 ... Probe electrode 102 ... Counter electrode 103 ... Reference electrode 104 ... Potentiostat 105 ... Vertical scan register 106 ... Horizontal scan register 107 ... Detection circuit

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01N 33/483 G01N 37/00 102 37/00 102 21/35 Z // G01N 21/35 27/46 336M (72) Inventor Naoya Masao 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center (72) Inventor Ikuo Fujiwara 1 Komu-shishi-cho, Saiwai-ku, Kawasaki, Kanagawa Co., Ltd. Toshiba R & D In-center (72) Inventor Yujiro Naruse 1 Komukai-Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa F-term in Toshiba Research and Development Center (Reference) 2G045 AA40 DA12 DA13 DA14 FA25 FB05 2G059 AA05 BB04 BB12 HH01 KK04 2G060 AA15 AE20 AF01 AF07 AG14 2G065 AA04 AB02 BA12 BA34 BC03 BC12 5C024 AX06 CX41 CX43 GX03 HX17 HX35

Claims (10)

[Claims] 1. A sensor array in which a sensor that detects a physical change amount or a chemical change amount and outputs an electric signal is arranged, a sense amplifier circuit that amplifies the electric signal, a first stage and a second stage. A current transfer circuit comprising a stage,
A current transfer circuit that transfers a first current appearing in the first stage as a second current to the second stage based on the amplified electric signal; and a second current that transfers the second current to the first stage. A current-voltage conversion circuit for converting into a voltage, a capacitor charged with electric charge, and a first load element connected to the capacitor, and the first load based on the first voltage. A first discharging / charging circuit for discharging the electric charge of the capacitor or charging the electric charge of the capacitor via an element; and a voltage change of the capacitor based on the discharging or charging by the first discharging / charging circuit. A sensor device comprising: an output circuit for outputting. 2. A second discharging / charging circuit for charging or discharging a charge to the capacitor, and based on a potential of a node between the capacitor and the second discharging / charging circuit. The sensor device according to claim 1, further comprising: a control circuit that controls the current-voltage conversion circuit. 3. The sense amplifier circuit is electrically connected to the sensor array, and is a load MOS transistor biased in a pentode region for converting the electric signal into a second voltage; and the second voltage. A MOS transistor for sensing that receives at its gate, the current transfer circuit includes a first current source load transistor connected to the drain of the sense MOS transistor, and a current with the first current source load transistor. A second current source load transistor configured as a mirror circuit, the drain of which is the second stage, wherein the current-voltage conversion circuit is a second load to which the second current is supplied. It has an element, The sensor apparatus of Claim 1 or 2 characterized by these. 4. The second load element is connected in parallel with a first NMOS transistor to which a fixed gate bias is applied, and the gate is driven based on the terminal voltage of the capacitor. 4. The sensor device according to claim 3, further comprising a second NMOS transistor that is formed. 5. The sense amplifier circuit has a collector and a base electrically connected to the sensor array, respectively.
A first bipolar transistor having an emitter connected to a reference potential and converting the electric signal into a second voltage; and a current mirror circuit with the first bipolar transistor, wherein the second voltage is supplied to the base. Second
And a gate connected to a collector of the second bipolar transistor and a first current source load transistor connected to a collector of the second bipolar transistor. A first NMOS transistor, a second current source load transistor connected to the drain of the first NMOS transistor and forming the current transfer circuit with the first current source load transistor, and the current-voltage conversion circuit The sensor device according to claim 1, further comprising a second load element connected to a source of the first NMOS transistor. 6. The second load element is connected in parallel with a second NMOS transistor to which a fixed gate bias is applied and the second NMOS transistor is connected in parallel to drive the gate based on the terminal voltage of the capacitor. 6. The sensor device according to claim 5, further comprising a third NMOS transistor that is formed. 7. The first discharging / charging circuit is configured to control the current-
For discharging, whose gate is driven by the output of the voltage conversion circuit
7. A charging transistor is provided, and the first load element is a resistor connected between a source of the discharging / charging transistor and a reference potential terminal. The sensor device according to claim 1. 8. A physical change amount or a chemical change amount is detected,
A sensor array in which sensors for outputting an electric signal are arranged; a capacitor; and a first array that is driven by a drive voltage based on the electric signal of the sensor array to discharge the charge of the capacitor or charge the capacitor. A discharging / charging circuit, a second discharging / charging circuit that charges the capacitor with electric charges or discharges electric charge from the capacitor, and a potential of a node between the capacitor and the second discharging / charging circuit And a control circuit that controls the drive voltage, and an output circuit that outputs a voltage change of the capacitor discharged or charged by the first discharge / charge circuit. 9. The sensor device according to claim 1, wherein the sensor is an infrared sensor using a diode as a thermoelectric conversion element. 10. The sensor is a DNA probe and a sample D.
The sensor device according to any one of claims 1 to 8, which is a DNA sensor that outputs a current due to an electrochemical reaction with NA.