WO2018235819A1 - Electromagnetic-wave detection device - Google Patents

Electromagnetic-wave detection device Download PDF

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Publication number
WO2018235819A1
WO2018235819A1 PCT/JP2018/023313 JP2018023313W WO2018235819A1 WO 2018235819 A1 WO2018235819 A1 WO 2018235819A1 JP 2018023313 W JP2018023313 W JP 2018023313W WO 2018235819 A1 WO2018235819 A1 WO 2018235819A1
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current
detection
electromagnetic wave
reference element
voltage
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PCT/JP2018/023313
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French (fr)
Japanese (ja)
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奥田　義行
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パイオニア株式会社
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits

Definitions

  • the present invention relates to the technical field of an electromagnetic wave detection device that detects an electromagnetic wave such as terahertz wave or millimeter wave.
  • an apparatus which acquires an image of a subject by irradiating the subject with an electromagnetic wave from an electromagnetic wave generation unit and detecting the electromagnetic wave reflected by the subject by the detection unit.
  • a Schottky barrier diode is used as a detection element (see Patent Document 1).
  • a current corresponding to the intensity of the electromagnetic wave (specifically, the current decreases as the intensity of the electromagnetic wave decreases) is generated in the detection element. If the current generated in the detection element due to the incidence of the electromagnetic wave is weak, for example, the current may not be detected due to the influence of background noise and the like. In the technology described in Patent Document 1, the detection sensitivity of the detection element is not considered.
  • the present invention has been made in view of, for example, the above-mentioned problems, and an object thereof is to provide an electromagnetic wave detection device capable of improving detection sensitivity.
  • the electromagnetic wave detection device is equivalent in electric characteristics to a detection element that generates a current according to the intensity of the incident electromagnetic wave and the detection element, and the detection sensitivity to the electromagnetic wave
  • a reference element smaller than the detection element, an offset section applying an offset current to the detection element or the reference element, and an offset voltage to the detection element or the reference element, and a current flowing through the detection element as the reference element
  • a voltage application unit that applies a voltage applied to the reference element to the detection element, and a detection unit that detects a current flowing through the detection element.
  • the electromagnetic wave detection device is equivalent to a detection element that generates a current according to the intensity of the incident electromagnetic wave, and the detection element and the electrical characteristics are equivalent, and the detection sensitivity to the electromagnetic wave is a reference element smaller than the detection element.
  • An offset unit for applying an offset current to the detection element or the reference element and an offset voltage for the detection element or the reference element; a current supply section for supplying a current flowing to the detection element to the reference element; A voltage application unit that applies a voltage to a detection element, and a detection unit that detects a current flowing to the detection element.
  • the “current flowing to the detection element” means (i) a current obtained by combining the current generated in the detection element upon incidence of the electromagnetic wave with the offset current when the offset current is applied to the detection element, and (ii) the offset When no current is applied to the detection element, it means the current generated in the detection element by the incidence of the electromagnetic wave.
  • the “voltage applied to the reference element” means (i) a voltage generated by combining the offset voltage with the voltage generated according to the current flowing to the reference element when the offset voltage is applied to the reference element ( ii) means the voltage generated in response to the current flowing in the reference element when the offset voltage is not applied to the reference element.
  • the current flowing to the reference element is (i) a current obtained by combining the current supplied by the current supply unit and the offset current when the offset current is applied to the reference element, and (ii) the offset current is If not applied to the reference element, it is the current supplied by the current supply.
  • the current supply unit supplies the current flowing through the detection element to the reference element
  • the voltage applied to the reference element changes according to the supplied current
  • the voltage application unit When a voltage applied to the element is applied to the detection element, the current flowing to the detection element changes in accordance with the applied voltage.
  • each of the detection element and the reference element has, as an electrical characteristic, a voltage-current characteristic in which a flowing current increases as the applied voltage increases.
  • a voltage corresponding to the supplied current is generated in the reference element.
  • the voltage generated in the reference element is increased.
  • the voltage generated in the reference element is applied to the detection element by the voltage application unit, a current corresponding to the applied voltage flows in the detection element. As a result, the current flowing to the detection element is increased.
  • the current generated in the detection element is also relatively small.
  • the current flowing to the detection element is increased by the actions of the current supply unit and the voltage application unit. For this reason, even when the intensity of the electromagnetic wave incident on the detection element is relatively weak, a large current flows in the detection element as compared to a device without the current supply unit and the voltage application unit. As a result, in the detection unit, the current resulting from the incidence of the electromagnetic wave on the detection element can be suitably detected. Therefore, according to the said electromagnetic wave detection apparatus, detection sensitivity can be improved.
  • the current supply unit includes a current mirror circuit. According to this aspect, the current generated in the detection element can be supplied to the reference element relatively easily.
  • the electromagnetic wave is a terahertz wave or a millimeter wave
  • the detection element is a Schottky barrier diode.
  • the terahertz wave or the millimeter wave can be suitably detected by the electromagnetic wave detection device.
  • the reference element is disposed in a shield that blocks the electromagnetic wave. According to this aspect, the detection sensitivity to the electromagnetic wave of the reference element can be made relatively easy and smaller than the detection element.
  • the reference element is placed in a thermal environment close to the thermal environment in which the detection element is placed. According to this aspect, it is possible to prevent the electrical characteristics of the detection element and the electrical characteristics of the reference element from being different due to the influence of heat.
  • FIG. 1 is a circuit diagram showing the configuration of an electromagnetic wave detection device according to an embodiment.
  • D1 and D2 are Schottky barrier diodes
  • OA is an operational amplifier
  • Q0 is an operational amplifier
  • Q1 is transistors.
  • the electromagnetic wave detection device 1 is configured to include the circuit shown in FIG. Schottky barrier diodes D1 and D2 are equivalent in electrical characteristics to each other.
  • “electrical characteristics are equivalent” is a concept including not only cases in which the electrical characteristics are completely equal but also cases in which the electrical characteristics are close to each other to such an extent that the electrical characteristics are practically equal.
  • the Schottky barrier diode D1 is placed in a thermal environment close to the thermal environment in which the Schottky barrier diode D2 is placed.
  • the electrical characteristics of each of Schottky barrier diodes D1 and D2 are affected by temperature change. If the Schottky barrier diodes D1 and D2 are placed in different thermal environments, the temperature effect on the electrical characteristics must be considered. However, in the present embodiment, since the Schottky barrier diodes D1 and D2 are placed in thermal environments close to each other, it is not necessary to be aware of the influence of temperature on the electrical characteristics.
  • the Schottky barrier diode D1 is covered by a shield made of a conductor that blocks the terahertz wave.
  • the Schottky barrier diode D1 covered by the shield is hereinafter appropriately referred to as "reference element 13".
  • the cathode of the reference element 13 is grounded via the offset voltage source.
  • the anode of the reference element 13 is electrically connected to the positive input terminal of the operational amplifier OA and the collector of the transistor Q1.
  • the cathode of the Schottky barrier diode D2 is grounded.
  • the anode of the Schottky barrier diode D2 is electrically connected to the negative input terminal of the operational amplifier OA and the source of the transistor Q0.
  • the output terminal of the operational amplifier OA is electrically connected to the gate of the transistor Q0.
  • the drain of the transistor Q0 is electrically connected to the collector of the transistor Q2.
  • the emitter of the transistor Q1 is electrically connected to the detection unit 12 via a resistance (resistance value R1).
  • the emitter of the transistor Q2 is electrically connected to the detection unit 12 via a resistance (resistance value R2).
  • the base of the transistor Q1 is electrically connected to the base of the transistor Q2.
  • the base of the transistor Q1 and the base of the transistor Q2 are electrically connected to the collector of the transistor Q2.
  • the current mirror circuit 11 is configured by the transistors Q1 and Q2.
  • the offset voltage and the offset current are applied to the reference element 13.
  • the potential of the cathode of the reference element 13 becomes “ ⁇ V” due to the offset voltage source. That is, the offset voltage is “ ⁇ V”.
  • the current flowing to the reference element 13 is “Id1”, and the current flowing to the Schottky barrier diode D2 is “Id2”.
  • the current value of each of the currents Id1 and Id2 is variable.
  • the negative input terminal of the operational amplifier OA is electrically connected to the output terminal of the operational amplifier OA via the transistor Q0 (ie, virtual ground). Therefore, the potential of the negative input terminal of the operational amplifier OA and the potential of the positive input terminal become the same potential. As a result, the voltage V1 is applied to the Schottky barrier diode D2 as a bias voltage.
  • the current value of the current Id2 also changes according to the voltage-current characteristics of the Schottky barrier diode D2 (typically, the current value increases). Since the current value of the current Id2 has changed, the current value of the current Id1 flowing to the reference element 13 also changes. As a result, the potential V1 of the positive input terminal of the operational amplifier OA changes, and the voltage applied to the Schottky barrier diode D2 also changes. That is, in the electromagnetic wave detection device 1, the current mirror circuit 11 and the operational amplifier OA constitute a positive feedback circuit.
  • FIG. 2 is a diagram showing an example of voltage-current characteristics of a Schottky barrier diode for each intensity of terahertz waves incident on the Schottky barrier diode.
  • the offset voltage and the offset current will be described as being absent.
  • Schottky barrier diodes D1 and D2 have the same electrical characteristics as each other.
  • both voltage-current characteristics of the Schottky barrier diodes D1 and D2 are assumed to be voltage-current characteristics shown in FIG.
  • the Schottky barrier diode D1 is covered by a shield and can not detect the terahertz wave. That is, it can be said that the reference element 13 has no detection sensitivity to the terahertz wave. Therefore, the relationship between the applied voltage Vd1 applied to the reference element 13 and the current Id1 flowing in the reference element 13 is as shown by the solid line graph in FIG. 2 (see “non-input characteristic”). On the other hand, the Schottky barrier diode D2 can detect terahertz waves.
  • the relationship between the voltage applied to the Schottky barrier diode D2 and the current Id2 flowing to the Schottky barrier diode D2 depends on the intensity of the incident terahertz wave, as shown in FIG. It looks like a dotted line, a broken line, an alternate long and short dash line or a double dotted line graph.
  • the graph showing the voltage-current characteristics of the Schottky barrier diode D1 and the graph showing the voltage-current characteristics of the Schottky barrier diode D2 are different from each other. Therefore, even if the current mirror circuit 11 and the operational amplifier OA constitute a positive feedback circuit, for example, the current value of the current Id2 converges to a certain current value without diverging.
  • the current value of current Id2 is the intersection of the graph of the solid line and the graph of the dotted line in FIG. It converges to the current value I1 of P1.
  • the graph showing the voltage-current characteristics of the Schottky barrier diode D2 is a graph of a two-dot chain line in FIG. 2
  • the current value of the current Id2 is a graph of a solid line graph and a two-dot chain line graph in FIG. It converges to the current value I2 of the intersection point P2.
  • the detection unit 12 outputs the current value of the current Id2 converged to a certain current value to, for example, a host computer (not shown).
  • a host computer for example, characteristic information indicating voltage-current characteristics concerning each of the Schottky barrier diodes D1 and D2 as shown in FIG. 2 is stored in advance.
  • the host computer specifies (estimates) the intensity of the terahertz wave incident on the Schottky barrier diode D2 based on the current value of the current Id2 output from the detection unit 12 and the characteristic information stored in advance.
  • intersection points P1 and P2 in FIG. 3 correspond to the intersection points P1 and P2 in FIG. 2, respectively.
  • the graph showing the voltage-current characteristics of the reference element 13 when the offset voltage and the offset current are applied to the reference element 13 is lateral to the graph showing the voltage-current characteristic of the reference element 13 without the offset voltage and the offset current.
  • Parallel movement is performed by “ ⁇ V” in the axial direction and by “ ⁇ I” in the vertical direction.
  • intersection point P1 of the solid line graph indicating no-input characteristics and the dotted line graph changes to an intersection point P1 ′.
  • an intersection point P2 between a solid line graph indicating no-input characteristics and a two-dot chain line graph changes to an intersection point P2 '. That is, by applying the offset voltage and the offset current to the reference element 13, the current value at which the current Id2 converges is suppressed.
  • the intensity of the terahertz wave is detected as follows.
  • a predetermined bias voltage V0 is applied to each of reference element 13 (ie, Schottky barrier diode D1) and Schottky barrier diode D2.
  • the operating point of the reference element 13 is, for example, the point A0 in FIG.
  • the operating point of the Schottky barrier diode D2 is, for example, the point A1 or the point A2 in FIG.
  • the difference between the current value at point A0 (that is, the current value flowing to reference element 13) and the current value at point A1 or A2 (that is, the current value flowing to Schottky barrier diode D2) is detected.
  • This difference changes according to the intensity of the terahertz wave. Therefore, from the detected difference, the intensity of the terahertz wave incident on the Schottky barrier diode D2 is detected.
  • the current Id2 flowing through the Schottky barrier diode D2 is amplified by the positive feedback circuit configured by the current mirror circuit 11 and the operational amplifier OA. Therefore, even when the intensity of the terahertz wave incident on the Schottky barrier diode D2 is relatively weak, the detection unit 12 detects the current Id2 having a larger current value than the intensity of the terahertz wave. In the case of the circuit shown in FIG. 1, a current (ie, “2 ⁇ Id2”) obtained by combining the current Id2 and the current Id1 is detected.
  • the electromagnetic wave detection device 1 it is possible to improve the detection sensitivity to the weak terahertz wave while suppressing the current Id2 when the relatively strong terahertz wave is incident on the Schottky barrier diode D2.
  • the “Schottky barrier diode D2”, the “current mirror circuit 11”, and the “op amp OA” according to the embodiment are examples of the “detection element”, the “current supply unit”, and the “voltage application unit” according to the present invention. is there.
  • the electromagnetic wave detection device 1 is applicable not only to terahertz waves but also to intensity detection of millimeter waves, for example.
  • the electromagnetic wave detection device 2 is configured to include the circuit shown in FIG. In FIG. 4, the base of the transistor Q2 is electrically connected to the base of the transistor Q3. The potential of the base of the transistor Q3, the potential of the base of the transistor Q2, and the potential of the collector of the transistor Q2 are equal. That is, the transistors Q2 and Q3 constitute a current mirror circuit. The collector of the transistor Q3 is electrically connected to the detection unit 12.
  • the current value of the current I3 becomes equal to the current value of the current Id2.
  • the detection unit 12 detects the current I3 and outputs the current value to, for example, a host computer (not shown).
  • the electromagnetic wave detection device 3 is configured to include the circuit shown in FIG. In FIG. 5, the anode of the reference element 13 is electrically connected to the positive input terminal of the operational amplifier OA and electrically connected to the output terminal of the operational amplifier OA via the resistance (resistance value R1).
  • the anode of the Schottky barrier diode D2 is electrically connected to the negative input terminal of the operational amplifier OA, and also electrically connected to the output terminal of the operational amplifier OA via the resistor R2.
  • the negative input terminal and the output terminal of the operational amplifier OA are electrically connected to each other through the resistance (resistance value R2). Therefore, the potential of the negative input terminal of the operational amplifier OA is the positive input terminal of the operational amplifier OA Equal to the potential of
  • the potential V0 of the output terminal of the operational amplifier OA changes in accordance with the current Id2 flowing through the Schottky barrier diode D2. Therefore, by detecting the potential V0, it is possible to detect the current Id2 indirectly.
  • the detection unit 12 'of the electromagnetic wave detection device 3 detects the potential V0 and outputs the voltage value to, for example, a host computer (not shown).
  • the reference element 13 can not detect a terahertz wave etc. by a shield, this invention is not limited to this.
  • the reference element 13 may be in any mode as long as the detection sensitivity of the terahertz wave or the like is smaller than that of the Schottky barrier diode D2.

Abstract

This electromagnetic-wave detection device (1) comprises: a detection element (D2) that generates a current corresponding to an intensity of an incident electromagnetic wave; a reference element (13) having electric characteristics that are equivalent to those of the detection element, and having a lower detection sensitivity to the electromagnetic wave than the detection element; an offset unit that applies an offset current to the detection element or the reference element and applies an offset voltage to the detection element or the reference element; a current supply unit (11) that supplies the current passing through the detection element to the reference element; a voltage application unit (OA) that applies a voltage applied to the reference element to the detection element; and a detection unit (12) that detects the current passing through the detection element.

Description

電磁波検出装置Electromagnetic wave detector
　本発明は、例えばテラヘルツ波、ミリ波等の電磁波を検出する電磁波検出装置の技術分野に関する。 The present invention relates to the technical field of an electromagnetic wave detection device that detects an electromagnetic wave such as terahertz wave or millimeter wave.
　この種の装置として、例えば電磁波発生部からの電磁波を被検体に照射し、該被検体で反射された電磁波を検出部により検出することで被検体の画像を取得する装置が提案されている。ここでは特に、検出素子としてショットキーバリアダイオードが用いられることが記載されている（特許文献１参照）。 As an apparatus of this type, for example, an apparatus has been proposed which acquires an image of a subject by irradiating the subject with an electromagnetic wave from an electromagnetic wave generation unit and detecting the electromagnetic wave reflected by the subject by the detection unit. Here, in particular, it is described that a Schottky barrier diode is used as a detection element (see Patent Document 1).
特開２０１４－２１９２２４号公報JP 2014-219224 A
　検出素子に電磁波が入射すると、電磁波の強度に応じた電流（具体的には、電磁波の強度が弱くなるほど電流は小さくなる）が検出素子に生じる。電磁波の入射に起因して検出素子に生じる電流が微弱であると、例えばバックグラウンドノイズ等の影響により該電流が検出されない可能性がある。特許文献１に記載の技術では、検出素子の検出感度については考慮されていない。 When an electromagnetic wave enters the detection element, a current corresponding to the intensity of the electromagnetic wave (specifically, the current decreases as the intensity of the electromagnetic wave decreases) is generated in the detection element. If the current generated in the detection element due to the incidence of the electromagnetic wave is weak, for example, the current may not be detected due to the influence of background noise and the like. In the technology described in Patent Document 1, the detection sensitivity of the detection element is not considered.
　本発明は、例えば上記問題点に鑑みてなされたものであり、検出感度を向上することができる電磁波検出装置を提供することを課題とする。 The present invention has been made in view of, for example, the above-mentioned problems, and an object thereof is to provide an electromagnetic wave detection device capable of improving detection sensitivity.
　本発明の電磁波検出装置は、上記課題を解決するために、入射する電磁波の強度に応じた電流を発生する検出素子と、前記検出素子と電気的特性が等価であって、前記電磁波に対する検出感度が前記検出素子より小さい基準素子と、前記検出素子又は前記基準素子にオフセット電流を加えると共に、前記検出素子又は前記基準素子にオフセット電圧を加えるオフセット部と、前記検出素子に流れる電流を前記基準素子に供給する電流供給部と、前記基準素子に印加された電圧を前記検出素子に印加する電圧印加部と、前記検出素子に流れる電流を検出する検出部と、を備える。 In order to solve the above problems, the electromagnetic wave detection device according to the present invention is equivalent in electric characteristics to a detection element that generates a current according to the intensity of the incident electromagnetic wave and the detection element, and the detection sensitivity to the electromagnetic wave A reference element smaller than the detection element, an offset section applying an offset current to the detection element or the reference element, and an offset voltage to the detection element or the reference element, and a current flowing through the detection element as the reference element And a voltage application unit that applies a voltage applied to the reference element to the detection element, and a detection unit that detects a current flowing through the detection element.
　本発明の作用及び他の利得は次に説明する実施するための形態から明らかにされる。 The operation and other advantages of the present invention will be apparent from the embodiments to be described below.
実施例に係る電磁波検出装置の構成を示す回路図である。It is a circuit diagram showing composition of an electromagnetic wave detection device concerning an example. ショットキーバリアダイオードの電圧電流特性の一例を、ショットキーバリアダイオードに入射するテラヘルツ波の強度毎に示す図である。It is a figure which shows an example of the voltage-current characteristic of a Schottky barrier diode for every intensity | strength of the terahertz wave which injects into a Schottky barrier diode. オフセット電圧及びオフセット電流の効果を説明するための図である。It is a figure for demonstrating the effect of offset voltage and offset current. 実施例の第１変形例に係る電磁波検出装置の構成を示す回路図である。It is a circuit diagram which shows the structure of the electromagnetic wave detection apparatus which concerns on the 1st modification of an Example. 実施例の第２変形例に係る電磁波検出装置の構成を示す回路図である。It is a circuit diagram which shows the structure of the electromagnetic wave detection apparatus which concerns on the 2nd modification of an Example.
　本発明の電磁波検出装置に係る実施形態について説明する。 An embodiment according to the electromagnetic wave detection device of the present invention will be described.
　実施形態に係る電磁波検出装置は、入射する電磁波の強度に応じた電流を発生する検出素子と、該検出素子と電気的特性が等価であって、電磁波に対する検出感度が該検出素子より小さい基準素子と、検出素子又は基準素子にオフセット電流を加えると共に、検出素子又は基準素子にオフセット電圧を加えるオフセット部と、検出素子に流れる電流を基準素子に供給する電流供給部と、基準素子に印加された電圧を検出素子に印加する電圧印加部と、検出素子に流れる電流を検出する検出部と、を備える。 The electromagnetic wave detection device according to the embodiment is equivalent to a detection element that generates a current according to the intensity of the incident electromagnetic wave, and the detection element and the electrical characteristics are equivalent, and the detection sensitivity to the electromagnetic wave is a reference element smaller than the detection element. An offset unit for applying an offset current to the detection element or the reference element and an offset voltage for the detection element or the reference element; a current supply section for supplying a current flowing to the detection element to the reference element; A voltage application unit that applies a voltage to a detection element, and a detection unit that detects a current flowing to the detection element.
　「検出素子に流れる電流」とは、（ｉ）オフセット電流が検出素子に加えられる場合、電磁波の入射により検出素子に発生した電流と、オフセット電流とが合わさった電流を意味し、（ｉｉ）オフセット電流が検出素子に加えられない場合、電磁波の入射により検出素子に発生した電流を意味する。 The “current flowing to the detection element” means (i) a current obtained by combining the current generated in the detection element upon incidence of the electromagnetic wave with the offset current when the offset current is applied to the detection element, and (ii) the offset When no current is applied to the detection element, it means the current generated in the detection element by the incidence of the electromagnetic wave.
　「基準素子に印加された電圧」とは、（ｉ）オフセット電圧が基準素子に加えられる場合、基準素子に流れる電流に応じて発生する電圧と、オフセット電圧とが合わさった電圧を意味し、（ｉｉ）オフセット電圧が基準素子に加えられない場合、基準素子に流れる電流に応じて発生する電圧を意味する。ここで、「基準素子に流れる電流」は、（ｉ）オフセット電流が基準素子に加えられる場合、電流供給部により供給される電流とオフセット電流とが合わさった電流であり、（ｉｉ）オフセット電流が基準素子に加えられない場合、電流供給部により供給される電流である。 The “voltage applied to the reference element” means (i) a voltage generated by combining the offset voltage with the voltage generated according to the current flowing to the reference element when the offset voltage is applied to the reference element ( ii) means the voltage generated in response to the current flowing in the reference element when the offset voltage is not applied to the reference element. Here, “the current flowing to the reference element” is (i) a current obtained by combining the current supplied by the current supply unit and the offset current when the offset current is applied to the reference element, and (ii) the offset current is If not applied to the reference element, it is the current supplied by the current supply.
　当該電磁波検出装置の動作時に、電流供給部が、検出素子に流れる電流を基準素子に供給すると、基準素子に印加された電圧が、供給された電流に応じて変化し、電圧印加部が、基準素子に印加された電圧を検出素子に印加すると、検出素子に流れる電流が、印加された電圧に応じて変化する。 During operation of the electromagnetic wave detection device, when the current supply unit supplies the current flowing through the detection element to the reference element, the voltage applied to the reference element changes according to the supplied current, and the voltage application unit When a voltage applied to the element is applied to the detection element, the current flowing to the detection element changes in accordance with the applied voltage.
　具体的には、検出素子及び基準素子各々は、電気的特性として、印加される電圧が高くなるほど、流れる電流が大きくなる電圧電流特性を有している。電流供給部により検出素子に発生した電流が基準素子に供給されると、供給された電流に応じた電圧が基準素子に発生する。この結果、基準素子に発生する電圧が増加する。基準素子に発生した電圧が、電圧印加部により検出素子に印加されると、印加された電圧に応じた電流が検出素子に流れる。この結果、検出素子に流れる電流が増大する。 Specifically, each of the detection element and the reference element has, as an electrical characteristic, a voltage-current characteristic in which a flowing current increases as the applied voltage increases. When the current generated in the detection element by the current supply unit is supplied to the reference element, a voltage corresponding to the supplied current is generated in the reference element. As a result, the voltage generated in the reference element is increased. When the voltage generated in the reference element is applied to the detection element by the voltage application unit, a current corresponding to the applied voltage flows in the detection element. As a result, the current flowing to the detection element is increased.
　検出素子に入射する電磁波の強度が比較的弱いと、検出素子に発生する電流も比較的小さい。当該電磁波検出装置では、電流供給部及び電圧印加部各々の作用により、検出素子に流れる電流が増大される。このため、検出素子に入射する電磁波の強度が比較的弱い場合であっても、電流供給部及び電圧印加部を有しない装置に比べて大きな電流が検出素子に流れる。この結果、検出部において、検出素子に電磁波が入射したことに起因する電流を好適に検出することができる。従って、当該電磁波検出装置によれば、検出感度を向上させることができる。 When the intensity of the electromagnetic wave incident on the detection element is relatively weak, the current generated in the detection element is also relatively small. In the electromagnetic wave detection device, the current flowing to the detection element is increased by the actions of the current supply unit and the voltage application unit. For this reason, even when the intensity of the electromagnetic wave incident on the detection element is relatively weak, a large current flows in the detection element as compared to a device without the current supply unit and the voltage application unit. As a result, in the detection unit, the current resulting from the incidence of the electromagnetic wave on the detection element can be suitably detected. Therefore, according to the said electromagnetic wave detection apparatus, detection sensitivity can be improved.
　尚、オフセット電圧及びオフセット電流の作用効果については、後述の実施例において詳述する。 The effects of the offset voltage and the offset current will be described in detail in the embodiments described later.
　実施形態に係る電磁波検出装置の一態様では、電流供給部は、カレントミラー回路を含む。この態様によれば、比較的容易にして、検出素子に発生した電流を基準素子に供給することができる。 In one aspect of the electromagnetic wave detection device according to the embodiment, the current supply unit includes a current mirror circuit. According to this aspect, the current generated in the detection element can be supplied to the reference element relatively easily.
　実施形態に係る電磁波検出装置の他の態様では、電磁波は、テラヘルツ波又はミリ波であって、検出素子は、ショットキーバリアダイオードである。この態様によれば、当該電磁波検出装置により、テラヘルツ波又はミリ波を好適に検出することができる。 In another aspect of the electromagnetic wave detection device according to the embodiment, the electromagnetic wave is a terahertz wave or a millimeter wave, and the detection element is a Schottky barrier diode. According to this aspect, the terahertz wave or the millimeter wave can be suitably detected by the electromagnetic wave detection device.
　実施形態に係る電磁波検出装置の他の態様では、基準素子は、電磁波を遮断するシールド内に配置されている。この態様によれば、基準素子の電磁波に対する検出感度を、比較的容易にして、検出素子よりも小さくすることができる。 In another aspect of the electromagnetic wave detection device according to the embodiment, the reference element is disposed in a shield that blocks the electromagnetic wave. According to this aspect, the detection sensitivity to the electromagnetic wave of the reference element can be made relatively easy and smaller than the detection element.
　実施形態に係る電磁波検出装置の他の態様では、基準素子は、検出素子が置かれた熱的環境と近い熱的環境に置かれている。この態様によれば、検出素子の電気的特性と基準素子の電気的特性とが熱の影響により互いに異なったものとなることを防止することができる。 In another aspect of the electromagnetic wave detection device according to the embodiment, the reference element is placed in a thermal environment close to the thermal environment in which the detection element is placed. According to this aspect, it is possible to prevent the electrical characteristics of the detection element and the electrical characteristics of the reference element from being different due to the influence of heat.
　本発明の電磁波検出装置に係る実施例について、図１乃至図３を参照して説明する。以下の実施例では、本発明に係る「電磁波」の一例として「テラヘルツ波」を挙げる。 An embodiment according to the electromagnetic wave detection device of the present invention will be described with reference to FIGS. 1 to 3. In the following examples, “terahertz wave” is mentioned as an example of “electromagnetic wave” according to the present invention.
　（電磁波検出装置の構成）
　実施例に係る電磁波検出装置について、図１を参照して説明する。図１は、実施例に係る電磁波検出装置の構成を示す回路図である。“Ｄ１”及び“Ｄ２”はショットキーバリアダイオードであり、“ＯＡ”はオペアンプであり、“Ｑ０”、“Ｑ１”及び“Ｑ２”はトランジスタである。 (Configuration of electromagnetic wave detection device)
An electromagnetic wave detection device according to an embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram showing the configuration of an electromagnetic wave detection device according to an embodiment. "D1" and "D2" are Schottky barrier diodes, "OA" is an operational amplifier, and "Q0", "Q1" and "Q2" are transistors.
　電磁波検出装置１は、図１に示す回路を備えて構成されている。ショットキーバリアダイオードＤ１及びＤ２は、互いに電気的特性が等価である。ここで、「電気的特性が等価」とは、電気的特性が全く等しい場合に限らず、電気的特性が等しいと実践上みなせる程度に、電気的特性が互いに近い場合も含む概念である。また、ショットキーバリアダイオードＤ１は、ショットキーバリアダイオードＤ２が置かれた熱的環境と近い熱的環境に置かれている。ショットキーバリアダイオードＤ１及びＤ２各々の電気的特性は温度変化の影響を受ける。仮に、ショットキーバリアダイオードＤ１及びＤ２が互いに異なる熱的環境に置かれるとすると、電気的特性に対する温度の影響を考慮しなければならない。しかるに本実施例では、ショットキーバリアダイオードＤ１及びＤ２が、互いに近い熱的環境に置かれるので、電気的特性に対する温度の影響を意識する必要が無い。 The electromagnetic wave detection device 1 is configured to include the circuit shown in FIG. Schottky barrier diodes D1 and D2 are equivalent in electrical characteristics to each other. Here, "electrical characteristics are equivalent" is a concept including not only cases in which the electrical characteristics are completely equal but also cases in which the electrical characteristics are close to each other to such an extent that the electrical characteristics are practically equal. In addition, the Schottky barrier diode D1 is placed in a thermal environment close to the thermal environment in which the Schottky barrier diode D2 is placed. The electrical characteristics of each of Schottky barrier diodes D1 and D2 are affected by temperature change. If the Schottky barrier diodes D1 and D2 are placed in different thermal environments, the temperature effect on the electrical characteristics must be considered. However, in the present embodiment, since the Schottky barrier diodes D1 and D2 are placed in thermal environments close to each other, it is not necessary to be aware of the influence of temperature on the electrical characteristics.
　ショットキーバリアダイオードＤ１は、テラヘルツ波を遮断する導電体からなるシールドにより覆われている。シールドにより覆われたショットキーバリアダイオードＤ１を、以降適宜「基準素子１３」と称する。 The Schottky barrier diode D1 is covered by a shield made of a conductor that blocks the terahertz wave. The Schottky barrier diode D1 covered by the shield is hereinafter appropriately referred to as "reference element 13".
　図１において、基準素子１３のカソードは、オフセット電圧源を介して、接地されている。基準素子１３のアノードは、オペアンプＯＡのプラスの入力端子及びトランジスタＱ１のコレクタと電気的に接続されている。ショットキーバリアダイオードＤ２のカソードは接地されている。ショットキーバリアダイオードＤ２のアノードは、オペアンプＯＡのマイナスの入力端子及びトランジスタＱ０のソースと電気的に接続されている。オペアンプＯＡの出力端子は、トランジスタＱ０のゲートと電気的に接続されている。トランジスタＱ０のドレインは、トランジスタＱ２のコレクタと電気的に接続されている。トランジスタＱ１のエミッタは、抵抗（抵抗値Ｒ１）を介して検出部１２と電気的に接続されている。トランジスタＱ２のエミッタは、抵抗（抵抗値Ｒ２）を介して検出部１２と電気的に接続されている。トランジスタＱ１のベースは、トランジスタＱ２のベースと電気的に接続されている。トランジスタＱ１のベース及びトランジスタＱ２のベース間と、トランジスタＱ２のコレクタとが電気的に接続されている。トランジスタＱ１及びＱ２により、カレントミラー回路１１が構成されている。 In FIG. 1, the cathode of the reference element 13 is grounded via the offset voltage source. The anode of the reference element 13 is electrically connected to the positive input terminal of the operational amplifier OA and the collector of the transistor Q1. The cathode of the Schottky barrier diode D2 is grounded. The anode of the Schottky barrier diode D2 is electrically connected to the negative input terminal of the operational amplifier OA and the source of the transistor Q0. The output terminal of the operational amplifier OA is electrically connected to the gate of the transistor Q0. The drain of the transistor Q0 is electrically connected to the collector of the transistor Q2. The emitter of the transistor Q1 is electrically connected to the detection unit 12 via a resistance (resistance value R1). The emitter of the transistor Q2 is electrically connected to the detection unit 12 via a resistance (resistance value R2). The base of the transistor Q1 is electrically connected to the base of the transistor Q2. The base of the transistor Q1 and the base of the transistor Q2 are electrically connected to the collector of the transistor Q2. The current mirror circuit 11 is configured by the transistors Q1 and Q2.
　本実施例では特に、基準素子１３にオフセット電圧及びオフセット電流が加えられる。オフセット電圧源により基準素子１３のカソードの電位は“－ΔＶ”となる。即ち、オフセット電圧は“－ΔＶ”である。 In the present embodiment, particularly, the offset voltage and the offset current are applied to the reference element 13. The potential of the cathode of the reference element 13 becomes “−ΔV” due to the offset voltage source. That is, the offset voltage is “−ΔV”.
　（電磁波検出装置の動作）
　次に、電磁波検出装置１の動作について説明する。基準素子１３に流れる電流を“Ｉｄ１”、ショットキーバリアダイオードＤ２に流れる“Ｉｄ２”とする。尚、電流Ｉｄ１及びＩｄ２各々の電流値は可変である。 (Operation of electromagnetic wave detection device)
Next, the operation of the electromagnetic wave detection device 1 will be described. The current flowing to the reference element 13 is “Id1”, and the current flowing to the Schottky barrier diode D2 is “Id2”. The current value of each of the currents Id1 and Id2 is variable.
　ショットキーバリアダイオードＤ２にテラヘルツ波が入射すると、ショットキーバリアダイオードＤ２に、テラヘルツ波の強度に応じた電流Ｉｄ２が発生する。このとき、カレントミラー回路１１により、基準素子１３に流れる電流Ｉｄ１の電流値は電流Ｉｄ２の電流値とオフセット電流の電流値ΔＩとの合計となる（即ち、Ｉｄ１＝Ｉｄ２＋ΔＩ）。基準素子１３に電流Ｉｄ１が流れると、ショットキーバリアダイオードＤ１の電圧電流特性に応じた電圧が基準素子１３に印加される。オペアンプＯＡのプラスの入力端子の電位を“Ｖ１”、基準素子１３に印加される印加電圧を“Ｖｄ１”とすると、“Ｖ１＝Ｖｄ１－ΔＶ”となる。 When the terahertz wave is incident on the Schottky barrier diode D2, a current Id2 corresponding to the intensity of the terahertz wave is generated in the Schottky barrier diode D2. At this time, due to the current mirror circuit 11, the current value of the current Id1 flowing through the reference element 13 is the sum of the current value of the current Id2 and the current value ΔI of the offset current (ie, Id1 = Id2 + ΔI). When the current Id1 flows in the reference element 13, a voltage corresponding to the voltage-current characteristic of the Schottky barrier diode D1 is applied to the reference element 13. Assuming that the potential of the positive input terminal of the operational amplifier OA is “V1” and the applied voltage applied to the reference element 13 is “Vd1,” “V1 = Vd1-ΔV” is obtained.
　図１に示すように、オペアンプＯＡのマイナスの入力端子は、トランジスタＱ０を介して、オペアンプＯＡの出力端子と電気的に接続されている（即ち、仮想接地）。このため、オペアンプＯＡのマイナスの入力端子の電位及びプラスの入力端子の電位は同電位となる。この結果、ショットキーバリアダイオードＤ２に、バイアス電圧として、電圧Ｖ１が印加される。 As shown in FIG. 1, the negative input terminal of the operational amplifier OA is electrically connected to the output terminal of the operational amplifier OA via the transistor Q0 (ie, virtual ground). Therefore, the potential of the negative input terminal of the operational amplifier OA and the potential of the positive input terminal become the same potential. As a result, the voltage V1 is applied to the Schottky barrier diode D2 as a bias voltage.
　ショットキーバリアダイオードＤ２に印加される電圧が変化したので、ショットキーバリアダイオードＤ２の電圧電流特性に応じて電流Ｉｄ２の電流値も変化する（典型的には、電流値が大きくなる）。電流Ｉｄ２の電流値が変化したので、基準素子１３に流れる電流Ｉｄ１の電流値も変化する。この結果、オペアンプＯＡのプラスの入力端子の電位Ｖ１が変化し、ショットキーバリアダイオードＤ２に印加される電圧も変化する。つまり、当該電磁波検出装置１では、カレントミラー回路１１及びオペアンプＯＡにより正帰還回路が構成される。 Since the voltage applied to the Schottky barrier diode D2 has changed, the current value of the current Id2 also changes according to the voltage-current characteristics of the Schottky barrier diode D2 (typically, the current value increases). Since the current value of the current Id2 has changed, the current value of the current Id1 flowing to the reference element 13 also changes. As a result, the potential V1 of the positive input terminal of the operational amplifier OA changes, and the voltage applied to the Schottky barrier diode D2 also changes. That is, in the electromagnetic wave detection device 1, the current mirror circuit 11 and the operational amplifier OA constitute a positive feedback circuit.
　（電磁波検出原理）
　次に、電磁波検出装置１における電磁波の検出原理について、図２を参照して説明する。図２は、ショットキーバリアダイオードの電圧電流特性の一例を、ショットキーバリアダイオードに入射するテラヘルツ波の強度毎に示す図である。尚、オフセット電圧及びオフセット電流の効果については後述するので、ここではオフセット電圧及びオフセット電流は無いものとして説明する。 (Primary of electromagnetic wave detection)
Next, the detection principle of the electromagnetic wave in the electromagnetic wave detection device 1 will be described with reference to FIG. FIG. 2 is a diagram showing an example of voltage-current characteristics of a Schottky barrier diode for each intensity of terahertz waves incident on the Schottky barrier diode. In addition, since the effects of the offset voltage and the offset current will be described later, here, the offset voltage and the offset current will be described as being absent.
　上述の如く、ショットキーバリアダイオードＤ１及びＤ２は、互いに電気的特性が等価である。ここでは、ショットキーバリアダイオードＤ１及びＤ２の電圧電流特性は、共に図２に示す電圧電流特性であるとする。 As described above, Schottky barrier diodes D1 and D2 have the same electrical characteristics as each other. Here, both voltage-current characteristics of the Schottky barrier diodes D1 and D2 are assumed to be voltage-current characteristics shown in FIG.
　ショットキーバリアダイオードＤ１はシールドにより覆われておりテラヘルツ波を検出することができない。つまり、基準素子１３は、テラヘルツ波に対して検出感度がないと言える。このため、基準素子１３に印加される印加電圧Ｖｄ１と基準素子１３に流れる電流Ｉｄ１との関係は、図２の実線のグラフ（“無入力特性”参照）のようになる。他方、ショットキーバリアダイオードＤ２はテラヘルツ波を検出することができる。テラヘルツ波がショットキーバリアダイオードＤ２に入射した場合、ショットキーバリアダイオードＤ２に印加される電圧とショットキーバリアダイオードＤ２に流れる電流Ｉｄ２との関係は、入射したテラヘルツ波の強度に応じて、図２の点線、破線、一点鎖線又はニ点鎖線のグラフのようになる。 The Schottky barrier diode D1 is covered by a shield and can not detect the terahertz wave. That is, it can be said that the reference element 13 has no detection sensitivity to the terahertz wave. Therefore, the relationship between the applied voltage Vd1 applied to the reference element 13 and the current Id1 flowing in the reference element 13 is as shown by the solid line graph in FIG. 2 (see “non-input characteristic”). On the other hand, the Schottky barrier diode D2 can detect terahertz waves. When the terahertz wave is incident on the Schottky barrier diode D2, the relationship between the voltage applied to the Schottky barrier diode D2 and the current Id2 flowing to the Schottky barrier diode D2 depends on the intensity of the incident terahertz wave, as shown in FIG. It looks like a dotted line, a broken line, an alternate long and short dash line or a double dotted line graph.
　テラヘルツ波の検出時には、ショットキーバリアダイオードＤ１の電圧電流特性を示すグラフと、ショットキーバリアダイオードＤ２の電圧電流特性を示すグラフとが互いに異なる。このため、カレントミラー回路１１及びオペアンプＯＡにより正帰還回路が構成されていても、例えば電流Ｉｄ２の電流値は発散せずにある電流値に収束する。 At the time of detection of the terahertz wave, the graph showing the voltage-current characteristics of the Schottky barrier diode D1 and the graph showing the voltage-current characteristics of the Schottky barrier diode D2 are different from each other. Therefore, even if the current mirror circuit 11 and the operational amplifier OA constitute a positive feedback circuit, for example, the current value of the current Id2 converges to a certain current value without diverging.
　具体的には、ショットキーバリアダイオードＤ２の電圧電流特性を示すグラフが、図２の点線のグラフであるとすると、電流Ｉｄ２の電流値は、図２において実線のグラフと点線のグラフとの交点Ｐ１の電流値Ｉ１に収束する。或いは、ショットキーバリアダイオードＤ２の電圧電流特性を示すグラフが、図２のニ点鎖線のグラフであるとすると、電流Ｉｄ２の電流値は、図２において実線のグラフとニ点鎖線のグラフとの交点Ｐ２の電流値Ｉ２に収束する。 Specifically, assuming that the graph showing the voltage-current characteristics of Schottky barrier diode D2 is the graph of the dotted line in FIG. 2, the current value of current Id2 is the intersection of the graph of the solid line and the graph of the dotted line in FIG. It converges to the current value I1 of P1. Alternatively, assuming that the graph showing the voltage-current characteristics of the Schottky barrier diode D2 is a graph of a two-dot chain line in FIG. 2, the current value of the current Id2 is a graph of a solid line graph and a two-dot chain line graph in FIG. It converges to the current value I2 of the intersection point P2.
　検出部１２は、ある電流値に収束した電流Ｉｄ２の電流値を、例えばホストコンピュータ（図示せず）に出力する。ホストコンピュータには、例えば図２に示すようなショットキーバリアダイオードＤ１及びＤ２各々に係る電圧電流特性を示す特性情報が予め格納されている。ホストコンピュータは、検出部１２から出力された電流Ｉｄ２の電流値と、予め格納された特性情報とに基づいて、ショットキーバリアダイオードＤ２に入射したテラヘルツ波の強度を特定（推定）する。 The detection unit 12 outputs the current value of the current Id2 converged to a certain current value to, for example, a host computer (not shown). In the host computer, for example, characteristic information indicating voltage-current characteristics concerning each of the Schottky barrier diodes D1 and D2 as shown in FIG. 2 is stored in advance. The host computer specifies (estimates) the intensity of the terahertz wave incident on the Schottky barrier diode D2 based on the current value of the current Id2 output from the detection unit 12 and the characteristic information stored in advance.
　（オフセット電圧及びオフセット電流の効果）
　図２に示すような電圧電流特性が関数ｆで表されるとする。基準素子１３に係る電圧電流特性は、印加電圧Ｖｄ１、電流Ｉｄ１として、“Ｉｄ１＝ｆ（Ｖｄ１）”と表せる。オフセット電圧及びオフセット電流が無い場合、“Ｉｄ１＝Ｉｄ２”及び“Ｖｄ１＝Ｖ１”であるので、上記式は、“Ｉｄ２＝ｆ（Ｖ１）”と表される。他方、オフセット電圧及びオフセット電流が基準素子１３に加えられる場合、“Ｉｄ１＝Ｉｄ２＋ΔＩ”及び“Ｖｄ１＝Ｖ１＋ΔＶ（∵Ｖ１＝Ｖｄ１－ΔＶ）”であるので、上記式は“Ｉｄ２＋ΔＩ＝ｆ（Ｖ１＋ΔＶ）”と表される。 (Effect of offset voltage and offset current)
It is assumed that a voltage-current characteristic as shown in FIG. 2 is represented by a function f. The voltage-current characteristics of the reference element 13 can be expressed as “Id1 = f (Vd1)” as the applied voltage Vd1 and the current Id1. When there is no offset voltage and offset current, since “Id1 = Id2” and “Vd1 = V1”, the above equation is expressed as “Id2 = f (V1)”. On the other hand, when the offset voltage and the offset current are applied to the reference element 13, “Id1 = Id2 + ΔI” and “Vd1 = V1 + ΔV (∵V1 = Vd1-ΔV)”, the above equation is “Id2 + ΔI = f (V1 + ΔV) It is expressed as
　ここで、図３を参照して説明を加える。尚、図３における交点Ｐ１及びＰ２は、図２における交点Ｐ１及びＰ２に夫々対応している。 Here, the description will be added with reference to FIG. The intersection points P1 and P2 in FIG. 3 correspond to the intersection points P1 and P2 in FIG. 2, respectively.
　オフセット電圧及びオフセット電流が無い場合の基準素子１３に係る電圧電流特性が、図３の「無入力特性（シフト前）」の実線のグラフであるとすると、オフセット電圧及びオフセット電流が基準素子１３に加えられる場合の基準素子１３の電圧電流特性は、図３の「無入力特性（シフト後）」の実線のグラフとなる。 Assuming that the voltage-current characteristics of the reference element 13 when there is no offset voltage and offset current are shown by the solid line graph of “No input characteristics (before shift)” in FIG. The voltage-current characteristic of the reference element 13 in the case of being added is a solid line graph of "no-input characteristic (after shift)" in FIG.
　オフセット電圧及びオフセット電流が基準素子１３に加えられる場合の基準素子１３の電圧電流特性を示すグラフは、オフセット電圧及びオフセット電流が無い場合の基準素子１３の電圧電流特性を示すグラフに対して、横軸方向に“－ΔＶ”、縦軸方向に“－ΔＩ”だけ並行移動していることになる。 The graph showing the voltage-current characteristics of the reference element 13 when the offset voltage and the offset current are applied to the reference element 13 is lateral to the graph showing the voltage-current characteristic of the reference element 13 without the offset voltage and the offset current. Parallel movement is performed by “−ΔV” in the axial direction and by “−ΔI” in the vertical direction.
　図３に示すように、オフセット電圧及びオフセット電流が基準素子１３に加えられることにより、無入力特性を示す実線のグラフと、点線のグラフとの交点Ｐ１が交点Ｐ１´に変化する。同様に、無入力特性を示す実線のグラフと、ニ点鎖線のグラフとの交点Ｐ２が交点Ｐ２´に変化する。つまり、オフセット電圧及びオフセット電流が基準素子１３に加えられることにより、電流Ｉｄ２が収束する電流値が抑制される。 As shown in FIG. 3, when the offset voltage and the offset current are applied to the reference element 13, the intersection point P1 of the solid line graph indicating no-input characteristics and the dotted line graph changes to an intersection point P1 ′. Similarly, an intersection point P2 between a solid line graph indicating no-input characteristics and a two-dot chain line graph changes to an intersection point P2 '. That is, by applying the offset voltage and the offset current to the reference element 13, the current value at which the current Id2 converges is suppressed.
　（技術的効果）
　カレントミラー回路１１及びオペアンプＯＡを備えない構成、つまり、正帰還回路を備えない構成では、次のようにテラヘルツ波の強度が検出される。基準素子１３（即ち、ショットキーバリアダイオードＤ１）及びショットキーバリアダイオードＤ２各々に所定のバイアス電圧Ｖ０が印加される。この場合、基準素子１３の動作点は、例えば図２の点Ａ０となる。テラヘルツ波が、ショットキーバリアダイオードＤ２に入射すると、該ショットキーバリアダイオードＤ２の動作点は、例えば図２の点Ａ１や点Ａ２等となる。点Ａ０の電流値（即ち、基準素子１３に流れる電流値）と、点Ａ１又はＡ２の電流値（即ち、ショットキーバリアダイオードＤ２に流れる電流値）との差分が検出される。この差分は、テラヘルツ波の強度に応じて変化する。このため、検出された差分から、ショットキーバリアダイオードＤ２に入射したテラヘルツ波の強度が検出される。 (Technical effect)
In the configuration without the current mirror circuit 11 and the operational amplifier OA, that is, the configuration without the positive feedback circuit, the intensity of the terahertz wave is detected as follows. A predetermined bias voltage V0 is applied to each of reference element 13 (ie, Schottky barrier diode D1) and Schottky barrier diode D2. In this case, the operating point of the reference element 13 is, for example, the point A0 in FIG. When the terahertz wave enters the Schottky barrier diode D2, the operating point of the Schottky barrier diode D2 is, for example, the point A1 or the point A2 in FIG. The difference between the current value at point A0 (that is, the current value flowing to reference element 13) and the current value at point A1 or A2 (that is, the current value flowing to Schottky barrier diode D2) is detected. This difference changes according to the intensity of the terahertz wave. Therefore, from the detected difference, the intensity of the terahertz wave incident on the Schottky barrier diode D2 is detected.
　このような構成では、テラヘルツ波の強度が比較的弱い場合、上記差分が比較的小さくなる。つまり、このような構成では、微弱なテラヘルツ波を適切に検出することが極めて困難である。 In such a configuration, when the intensity of the terahertz wave is relatively weak, the difference is relatively small. That is, in such a configuration, it is extremely difficult to appropriately detect weak terahertz waves.
　当該電磁波検出装置１では、上述の如く、カレントミラー回路１１及びオペアンプＯＡにより構成される正帰還回路により、ショットキーバリアダイオードＤ２に流れる電流Ｉｄ２が増幅される。このため、ショットキーバリアダイオードＤ２に入射するテラヘルツ波の強度が比較的弱い場合であっても、テラヘルツ波の強度に比べて大きな電流値の電流Ｉｄ２が検出部１２により検出される。図１に示す回路の場合、電流Ｉｄ２と電流Ｉｄ１とが合わさった電流（即ち、“２×Ｉｄ２”）が検出される。 In the electromagnetic wave detection device 1, as described above, the current Id2 flowing through the Schottky barrier diode D2 is amplified by the positive feedback circuit configured by the current mirror circuit 11 and the operational amplifier OA. Therefore, even when the intensity of the terahertz wave incident on the Schottky barrier diode D2 is relatively weak, the detection unit 12 detects the current Id2 having a larger current value than the intensity of the terahertz wave. In the case of the circuit shown in FIG. 1, a current (ie, “2 × Id2”) obtained by combining the current Id2 and the current Id1 is detected.
　他方で、ショットキーバリアダイオードＤ２に入射するテラヘルツ波の強度が比較的強い場合、何らの対策も採らなければ、上記正帰還回路の作用により比較的大きな電流が、当該電磁波検出素子１が備える回路に流れる可能性がある。しかるに本実施例では、オフセット電圧及びオフセット電流が基準素子１３に加えられるので、上述の如く電流Ｉｄ２が収束する電流値を抑制することができる。このため、ショットキーバリアダイオードＤ２に入射するテラヘルツ波の強度が比較的強い場合であっても、電流Ｉｄ２を抑制することができる。 On the other hand, when the intensity of the terahertz wave incident on the Schottky barrier diode D2 is relatively strong, a circuit having a relatively large current due to the action of the positive feedback circuit is provided if no measures are taken. May flow to However, in the present embodiment, since the offset voltage and the offset current are applied to the reference element 13, the current value at which the current Id2 converges can be suppressed as described above. Therefore, even when the intensity of the terahertz wave incident on the Schottky barrier diode D2 is relatively strong, the current Id2 can be suppressed.
　従って、当該電磁波検出装置１によれば、比較的強いテラヘルツ波がショットキーバリアダイオードＤ２に入射する場合の電流Ｉｄ２を抑制しつつ、微弱なテラヘルツ波に対する検出感度を向上させることができる。 Therefore, according to the electromagnetic wave detection device 1, it is possible to improve the detection sensitivity to the weak terahertz wave while suppressing the current Id2 when the relatively strong terahertz wave is incident on the Schottky barrier diode D2.
　実施例に係る「ショットキーバリアダイオードＤ２」、「カレントミラー回路１１」及び「オペアンプＯＡ」は、夫々、本発明に係る「検出素子」、「電流供給部」及び「電圧印加部」の一例である。 The “Schottky barrier diode D2”, the “current mirror circuit 11”, and the “op amp OA” according to the embodiment are examples of the “detection element”, the “current supply unit”, and the “voltage application unit” according to the present invention. is there.
　尚、電磁波検出装置１は、テラヘルツ波に限らず、例えばミリ波の強度検出にも適用可能である。 The electromagnetic wave detection device 1 is applicable not only to terahertz waves but also to intensity detection of millimeter waves, for example.
　＜第１変形例＞
　第１変形例に係る電磁波検出装置２は、図４に示す回路を備えて構成されている。図４において、トランジスタＱ２のベースは、トランジスタＱ３のベースと電気的に接続されている。トランジスタＱ３のベースの電位とトランジスタＱ２のベースの電位とトランジスタＱ２のコレクタの電位とは等しい。つまり、トランジスタＱ２及びＱ３によりカレントミラー回路が構成されている。トランジスタＱ３のコレクタは、検出部１２と電気的に接続されている。 First Modified Example
The electromagnetic wave detection device 2 according to the first modification is configured to include the circuit shown in FIG. In FIG. 4, the base of the transistor Q2 is electrically connected to the base of the transistor Q3. The potential of the base of the transistor Q3, the potential of the base of the transistor Q2, and the potential of the collector of the transistor Q2 are equal. That is, the transistors Q2 and Q3 constitute a current mirror circuit. The collector of the transistor Q3 is electrically connected to the detection unit 12.
　トランジスタＱ２及びＱ３により構成されるカレントミラー回路の作用により、電流Ｉ３の電流値は、電流Ｉｄ２の電流値と等しくなる。検出部１２は、電流Ｉ３を検出して、その電流値を、例えばホストコンピュータ（図示せず）に出力する。 By the action of the current mirror circuit constituted by the transistors Q2 and Q3, the current value of the current I3 becomes equal to the current value of the current Id2. The detection unit 12 detects the current I3 and outputs the current value to, for example, a host computer (not shown).
　＜第２変形例＞
　第２変形例に係る電磁波検出装置３は、図５に示す回路を備えて構成されている。図５において、基準素子１３のアノードは、オペアンプＯＡのプラスの入力端子と電気的に接続されると共に、抵抗（抵抗値Ｒ１）を介してオペアンプＯＡの出力端子と電気的に接続されている。ショットキーバリアダイオードＤ２のアノードは、オペアンプＯＡのマイナスの入力端子と電気的に接続されると共に、抵抗Ｒ２を介してオペアンプＯＡの出力端子と電気的に接続されている。 Second Modified Example
The electromagnetic wave detection device 3 according to the second modification is configured to include the circuit shown in FIG. In FIG. 5, the anode of the reference element 13 is electrically connected to the positive input terminal of the operational amplifier OA and electrically connected to the output terminal of the operational amplifier OA via the resistance (resistance value R1). The anode of the Schottky barrier diode D2 is electrically connected to the negative input terminal of the operational amplifier OA, and also electrically connected to the output terminal of the operational amplifier OA via the resistor R2.
　オペアンプＯＡのマイナスの入力端子及び出力端子とは、抵抗（抵抗値Ｒ２）を介して、電気的に接続されているので、オペアンプＯＡのマイナスの入力端子の電位は、オペアンプＯＡのプラスの入力端子の電位と等しくなる。 The negative input terminal and the output terminal of the operational amplifier OA are electrically connected to each other through the resistance (resistance value R2). Therefore, the potential of the negative input terminal of the operational amplifier OA is the positive input terminal of the operational amplifier OA Equal to the potential of
　オペアンプＯＡのプラスの入力端子の電位を“Ｖ１”とすると、オペアンプＯＡのマイナスの入力端子の電位も“Ｖ１”となる。また、オペアンプＯＡの出力端子の電位を“Ｖ０”とすると、“Ｖ０＝Ｖ１＋Ｉｄ２×Ｒ２”となる。抵抗値Ｒ１及びＲ２が等しければ、電流Ｉｄ１は、“Ｉｄ１＝Ｉｄ２＋ΔＩ”となる。 Assuming that the potential at the positive input terminal of the operational amplifier OA is "V1", the potential at the negative input terminal of the operational amplifier OA also becomes "V1". Further, when the potential of the output terminal of the operational amplifier OA is “V0”, “V0 = V1 + Id2 × R2” is obtained. If the resistance values R1 and R2 are equal, the current Id1 is “Id1 = Id2 + ΔI”.
　オペアンプＯＡの出力端子の電位Ｖ０は、ショットキーバリアダイオードＤ２に流れる電流Ｉｄ２に応じて変化する。このため、電位Ｖ０を検出することで、間接的に電流Ｉｄ２を検出することができる。電磁波検出装置３の検出部１２´は、電位Ｖ０を検出して、その電圧値を、例えばホストコンピュータ（図示せず）に出力する。 The potential V0 of the output terminal of the operational amplifier OA changes in accordance with the current Id2 flowing through the Schottky barrier diode D2. Therefore, by detecting the potential V0, it is possible to detect the current Id2 indirectly. The detection unit 12 'of the electromagnetic wave detection device 3 detects the potential V0 and outputs the voltage value to, for example, a host computer (not shown).
　また、上述の実施例では、基準素子１３がシールドによってテラヘルツ波等を検出できないとあるが、本発明はこれに限定されない。基準素子１３は、ショットキーバリアダイオードＤ２と比較して、テラヘルツ波等の検出感度が小さくなっている態様であればよい。 Moreover, in the above-mentioned Example, although the reference element 13 can not detect a terahertz wave etc. by a shield, this invention is not limited to this. The reference element 13 may be in any mode as long as the detection sensitivity of the terahertz wave or the like is smaller than that of the Schottky barrier diode D2.
　本発明は、上述した実施形態に限られるものではなく、請求の範囲及び明細書全体から読み取れる発明の要旨或いは思想に反しない範囲で適宜変更可能であり、そのような変更を伴う電磁波検出装置もまた本発明の技術的範囲に含まれるものである。 The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the scope or spirit of the invention as can be read from the claims and the specification as a whole. Moreover, it is contained in the technical scope of this invention.
　１…電磁波検出装置、１１…カレントミラー回路、１２…検出部、１３…基準素子、Ｄ１、Ｄ２…ショットキーバリアダイオード、ＯＡ…オペアンプ DESCRIPTION OF SYMBOLS 1 ... Electromagnetic wave detection apparatus, 11 ... Current mirror circuit, 12 ... Detection part, 13 ... Reference element, D1, D2 ... Schottky barrier diode, OA ... Operational amplifier

Claims (6)

  1. 　入射する電磁波の強度に応じた電流を発生する検出素子と、
    　前記検出素子と電気的特性が等価であって、前記電磁波に対する検出感度が前記検出素子より小さい基準素子と、
    　前記検出素子又は前記基準素子にオフセット電流を加えると共に、前記検出素子又は前記基準素子にオフセット電圧を加えるオフセット部と、
    　前記検出素子に流れる電流を前記基準素子に供給する電流供給部と、
    　前記基準素子に印加された電圧を前記検出素子に印加する電圧印加部と、
    　前記検出素子に流れる電流を検出する検出部と、
    　を備える電磁波検出装置。     A detection element that generates a current according to the intensity of the incident electromagnetic wave;
    A reference element that is equivalent in electrical characteristics to the detection element and has a detection sensitivity to the electromagnetic wave that is smaller than the detection element;
    An offset unit that applies an offset current to the detection element or the reference element and applies an offset voltage to the detection element or the reference element;
    A current supply unit for supplying a current flowing through the detection element to the reference element;
    A voltage application unit that applies a voltage applied to the reference element to the detection element;
    A detection unit that detects a current flowing to the detection element;
    An electromagnetic wave detection device comprising
  2. 　当該電磁波検出装置の動作時に、
    　前記電流供給部が、前記検出素子に流れる電流を前記基準素子に供給すると、前記基準素子に印加された電圧が、前記供給された電流に応じて変化し、
    　前記電圧印加部が、前記基準素子に印加された電圧を前記検出素子に印加すると、前記検出素子に流れる電流が、前記印加された電圧に応じて変化する
    　ことを特徴とする請求項１に記載の電磁波検出装置。     During operation of the electromagnetic wave detection device
    When the current supply unit supplies a current flowing to the detection element to the reference element, a voltage applied to the reference element is changed according to the supplied current.
    When the voltage application unit applies a voltage applied to the reference element to the detection element, a current flowing through the detection element changes in accordance with the applied voltage. Electromagnetic wave detection device.
  3. 　前記電流供給部は、カレントミラー回路を含むことを特徴とする請求項１に記載の電磁波検出装置。 The electromagnetic wave detection device according to claim 1, wherein the current supply unit includes a current mirror circuit.
  4. 　前記電磁波は、テラヘルツ波又はミリ波であって、
    　前記検出素子は、ショットキーバリアダイオードである
    　ことを特徴とする請求項１に記載の電磁波検出装置。     The electromagnetic waves are terahertz waves or millimeter waves, and
    The electromagnetic wave detection device according to claim 1, wherein the detection element is a Schottky barrier diode.
  5. 　前記基準素子は、前記電磁波を遮断するシールド内に配置されていることを特徴とする請求項１に記載の電磁波検出装置。 The electromagnetic wave detection device according to claim 1, wherein the reference element is disposed in a shield that blocks the electromagnetic wave.
  6. 　前記基準素子は、前記検出素子が置かれた熱的環境と近い熱的環境に置かれていることを特徴とする請求項１に記載の電磁波検出装置。 The electromagnetic wave detection device according to claim 1, wherein the reference element is placed in a thermal environment close to a thermal environment in which the detection element is placed.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005525708A (en) * 2002-01-17 2005-08-25 カペラ マイクロシステムズ，インコーポレイテッド Photodetection system and amplifier circuit
JP2009047688A (en) * 2007-07-25 2009-03-05 Semiconductor Energy Lab Co Ltd Photoelectric conversion device and electronic device with same
JP2009186457A (en) * 2008-01-08 2009-08-20 Mitsubishi Electric Corp Thermal infrared detection element
JP2010085396A (en) * 2008-09-04 2010-04-15 Semiconductor Energy Lab Co Ltd Photodetector
US20150338269A1 (en) * 2014-05-22 2015-11-26 International Business Machines Corporation Offset current compensation for photodiodes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005525708A (en) * 2002-01-17 2005-08-25 カペラ マイクロシステムズ，インコーポレイテッド Photodetection system and amplifier circuit
JP2009047688A (en) * 2007-07-25 2009-03-05 Semiconductor Energy Lab Co Ltd Photoelectric conversion device and electronic device with same
JP2009186457A (en) * 2008-01-08 2009-08-20 Mitsubishi Electric Corp Thermal infrared detection element
JP2010085396A (en) * 2008-09-04 2010-04-15 Semiconductor Energy Lab Co Ltd Photodetector
US20150338269A1 (en) * 2014-05-22 2015-11-26 International Business Machines Corporation Offset current compensation for photodiodes

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