WO2021070903A1

WO2021070903A1 - Electromagnetic wave generating device

Info

Publication number: WO2021070903A1
Application number: PCT/JP2020/038119
Authority: WO
Inventors: 田中　博之; 小林　秀樹
Original assignee: パイオニア株式会社
Priority date: 2019-10-09
Filing date: 2020-10-08
Publication date: 2021-04-15
Also published as: JPWO2021070903A1; JP7346584B2

Abstract

The present invention comprises: a plurality of electromagnetic wave generating elements to which drive voltage is supplied, each of which elements generates electromagnetic waves in response to the drive voltage; a DC voltage source that generates with variable voltage a plurality of DC voltages corresponding to each of the plurality of electromagnetic wave generating elements; a modulated voltage source that generates a modulated voltage in which the voltage value changes periodically between prescribed binary voltage values in the plurality of electromagnetic wave generating elements; a supply unit that adds each of the plurality of DC voltages and the modulated voltage and supplies these to the plurality of electromagnetic wave generating elements; and a control unit that controls the DC voltage source to change the voltage value of each of the plurality of DC voltages independently of each other.

Description

Electromagnetic wave generator

The present invention relates to an electromagnetic wave generator, and more particularly to an electromagnetic wave generator that drives a plurality of electromagnetic wave generators in parallel.

For example, a resonant tunneling diode (hereinafter referred to as RTD) is known as an electromagnetic wave generating element of a measuring device using electromagnetic waves in the terahertz band distributed over a frequency band of 0.1 THz to 10 THz. The RTD is an element having a differential negative resistance (Negative Differential Resistance: hereinafter referred to as NDR) region in the voltage-current characteristic, and generates an electromagnetic wave in the terahertz band by applying a bias voltage in the differential negative resistance region.

For example, in Patent Document 1, terahertz is obtained by repeatedly applying a DC offset voltage and a pulsed voltage to an RTD oscillating element as a terahertz wave oscillating element to repeatedly generate an electromagnetic wave generation state and a non-generation state. It is disclosed that an amplitude shift keying method (Amplitude Shift Keying: hereinafter referred to as ASK) is realized by an electromagnetic wave in a band.

Japanese Patent No. 60999914

As a method of applying the above-mentioned offset pulsed bias voltage to the RTD oscillating element, control of the output voltage by a digital-to-analog conversion circuit (hereinafter referred to as DAC) can be mentioned.

Further, when a plurality of RTD oscillating elements are used as a generation source in an electromagnetic wave measuring device, interference occurs between terahertz waves generated from each of the RTD oscillating elements. When a dark portion of interference fringes is generated at the position of the terahertz wave detection element in the detection unit of the electromagnetic wave measuring device, there arises a problem that the detection value of the terahertz wave detection element becomes small.

When the interference of terahertz waves becomes a problem, it is effective to set a time difference between the generation of terahertz waves of the RTD oscillating elements that cause interference with each other so as not to cause interference fringes.

In a system such as the one described above in which a desired RTD oscillating element is selectively driven by using a plurality of RTD oscillating elements, a multi-channel DAC is used in order to generate a bias voltage according to the number of elements. Is desirable.

However, in the case of alternately changing the output voltage at a high modulation frequency like ASK, a high-speed DAC is required, and if the high-speed DAC is multi-elemented on the IC chip according to the number of a plurality of RTD oscillating elements, The circuit on the IC chip becomes large in scale, leading to high cost. In addition, a large number of control signals for controlling the high-speed DAC are required.

The present invention has been made in view of the above points, and parallel control of a plurality of RTD oscillating elements driven at a high modulation frequency can be performed without increasing the scale and cost of the circuit while using the DAC. One of the purposes is to provide a possible electromagnetic wave generator.

According to the first aspect of the present invention, a driving voltage is supplied, and a plurality of electromagnetic wave generating elements, each of which generates an electromagnetic wave in response to the drive voltage, and a plurality of DC voltages corresponding to each of the plurality of electromagnetic wave generating elements are voltageed. A variably generated DC voltage source, a modulated voltage source that generates a modulated voltage in which the voltage value periodically changes between a predetermined binary voltage value in the plurality of electromagnetic wave generating elements, and the plurality of DC voltages. A supply unit that adds each of the modulation voltages and supplies them to the plurality of electromagnetic wave generating elements, and a control that controls the DC voltage source to change the voltage values of the plurality of DC voltages independently of each other. It is characterized by having a part and.

It is a functional block diagram which shows the structure of the electromagnetic wave generator 1 by this invention. It is a graph which shows an example of the voltage-current characteristic of an RTD oscillator. _{It is a time chart which shows the change of the drive voltage V Dr} applied to the RTD oscillating element to operate, and the change of the terahertz wave generated from the RTD oscillating element correspondingly. _{It is a time chart which shows the change of the drive voltage V Dr} applied to the RTD oscillator which is not the operation target, and the change of the terahertz wave generated from the RTD oscillator correspondingly.

Hereinafter, examples of the present invention will be described in detail.

FIG. 1 is a functional block diagram showing the configuration of the electromagnetic wave generator 1 according to the present invention.

The electromagnetic wave generator 1 includes a control unit 10 that supplies a control signal for instructing the generation of a terahertz wave. Further, the electromagnetic wave generator 1 has a multi-channel DAC20 which is a DC voltage source that outputs a DC voltage from a plurality of output terminals and an ASK modulation frequency, and outputs a binary voltage value by periodically changing the voltage value. It has a high-speed DAC 30 to be used, m adder 40s for adding the output of the multi-channel DAC 20 and the output of the high-speed DAC 30, and m RTD oscillating elements 50 which are terahertz wave generation sources.

The control unit 10 is connected to the multi-channel DAC 20 and supplies an offset voltage control signal for controlling each voltage value of the _{DC offset voltage V Offset} 1 to V _{Offset m output from the output end of the multi-channel DAC 20.} Further, the control unit 10 is connected to the high-speed DAC 30 and supplies a modulation voltage control signal for controlling the voltage amplitude and frequency of _{the modulation voltage V AC output by the high-speed DAC 30.}

The multi-channel DAC 20 is a DC voltage source having m output ends. Each of the m output ends is connected to each of the m adders 40. The multi-channel DAC 20 variably controls each voltage value of _{the DC offset voltage V Offset} 1 to V _Offset m output from each output end based on the offset voltage control signal supplied from the control unit 10. It operates to output from each output end.

The high-speed DAC 30 is a voltage source having one output end that outputs a _{modulated voltage V AC} whose voltage value changes periodically like a square wave, for example. The output end is connected to each of m adders 40. The high-speed DAC 30 operates so as to variably output the maximum voltage value, the minimum voltage value, and the frequency of _{the modulation voltage V AC} based on the modulation voltage control signal supplied from the control unit 10. Specifically, for example, the high-speed DAC 30 changes the maximum voltage value, the minimum voltage value, and the pulse generation cycle of _{the output modulation voltage V AC based on the modulation voltage control signal.}

The m adders 40 are connected to the respective output ends of the m multi-channel DAC 20s and the output ends of the high-speed DAC 30. _{The m adders 40 have a DC offset voltage V Offset} 1 to V _Offset m output from each of the m output ends of the multi-channel DAC 20 _{and a modulation voltage V AC} output from the high-speed DAC 30. And are added by each adder and output. That is, the m adders 40 generate drive voltages V _Dr 1 to V _Dr _{m in which the modulation voltage V AC} is offset by the offset voltages V _Offset 1 to V _Offset m, respectively, and adder of each of the adders 40. Operates to output from the device.

The m RTD oscillators 50 are connected to each of the output ends of the m adders 40, and the drive voltages V _Dr 1 to V _Dr m generated by the m adders 40 are m RTD oscillations. It is supplied to each of the elements 50. The m RTD oscillators 50 generate terahertz waves from their respective RTD oscillators based on _{the supplied drive voltages V Dr} 1 to V _{Dr m.}

FIG. 2 is a schematic view showing the voltage-current characteristics of the RTD oscillator.

As shown in FIG. 2, it is known that when a positive bias voltage is applied to the RTD oscillating element, the current changes linearly as the applied voltage rises (between points a and b). .. However, it is known that a strong non-linear region appears in a predetermined voltage region (between points bc). It is known that when the applied voltage is further increased, an NDR region in which the current decreases with the applied voltage appears (between points cd).

It is known that an electromagnetic wave in the terahertz band is generated from the RTD oscillating element by applying a bias voltage corresponding to the NDR region of the RTD oscillating element.

That is, by applying a bias voltage in the range of the terahertz wave oscillation region of the bias voltage values V _NDR 1 to V _NDR 2, it is possible to generate a terahertz wave from the RTD oscillating element. In other words, the maximum operating voltage of this RTD oscillator is _VNDR 2, and the minimum operating voltage is _VNDR 1.

Further, by applying a voltage having an ASK modulation frequency to the bias voltage in the range of the terahertz wave oscillation region of the bias voltages V _NDR 1 to V _{NDR 2, a terahertz wave can be generated intermittently according to the modulation frequency.} It will be possible.

_{The control unit 10 has a DC offset voltage V Offset} 1 to V _Offset m output by the multi-channel DAC 20 among the _{drive voltages V Dr} 1 to V _Dr m supplied to the m RTD oscillators 50. By controlling the above, the terahertz wave is controlled to be generated only in the desired RTD oscillating element out of the m RTD oscillating elements 50.

_{At this time, from the high-speed DAC 30, a modulation voltage V AC} of the same frequency and voltage is applied to both the RTD oscillator element that generates the terahertz wave and the RTD oscillator element that does not generate the terahertz wave. _{That is, the control unit 10 has a high potential drive voltage V Dr} that oscillates the RTD oscillating element from the output end corresponding to the RTD oscillating element that generates the terahertz wave among the m output ends of the multi-channel DAC 20. _Is to output the offset voltage V Offset that offsets the modulation voltage V _AC. _{Specifically, for example, the offset voltage V Offset} is output so that the drive voltage V _Dr having the above-mentioned bias voltage values V _NDR 1 to V _NDR 2 is output from the adder 40. On the other hand, a low offset voltage V _Offset is supplied or an offset voltage is supplied _{so that a drive voltage V Dr that} is less than the potential oscillated by the RTD oscillating element is output from the output end corresponding to the RTD oscillating element that does not generate a terahertz wave. Stop the supply of V _Offset. Specifically, for example, the _{offset voltage V Offset} is output so that the drive voltage V _Dr _{having a bias voltage value V NDR} 1 to V _NDR 2 or less described above is output from the adder 40.

The control unit 10 controls so as to generate a terahertz wave only in a desired RTD oscillating element _{by selectively supplying a high offset voltage V Offset to each adder 40 in this way.}

With the above configuration, the electromagnetic wave generator 1 of the present invention can control one multi-channel DAC 20 and one high-speed DAC 30 to selectively operate m RTD oscillators 50, and can control the DAC. It is possible to control multiple elements of the RTD oscillator element corresponding to a high modulation frequency without inviting an increase in scale and cost of the circuit of the IC chip including the IC chip.

_{FIG. 3 is a schematic time chart of the drive voltage V Dr} applied to the RTD oscillator that emits the terahertz wave and the terahertz wave output of the RTD oscillator. _{Further, FIG. 4 is a schematic time chart of the drive voltage V Dr} applied to the RTD oscillator that does not emit the terahertz wave and the terahertz wave output of the RTD oscillator.

The operation of the electromagnetic wave generator 1 of this embodiment will be described with reference to FIGS. 3 and 4.

The upper figure of FIG. 3 shows a time chart of the _{drive voltage V Dr} supplied to the RTD oscillating element that periodically generates the terahertz wave to be operated among the m RTD oscillating elements 50.

_{The drive voltage V Dr} applied to the RTD oscillator has a voltage value obtained by adding the _{V Offset} output from the multi-channel DAC 20 and the rectangular wave voltage V _{AC output from the high-speed DAC 30 as described above.}

Therefore, the driving voltage V _Dr, according to the voltage value of the binary minimum value maximum value is an offset voltage V _Offset is the maximum voltage of the offset voltage V _Offset + modulation voltage V _AC to the frequency of the modulation voltage V _AC cycle Has a voltage profile that repeats.

_{The control unit 10 has a bias voltage V NDR} 1 to V _NDR 2 at which _{the maximum voltage value of the drive voltage V Dr is} a voltage value within the terahertz wave oscillation region with respect to the multi-channel DAC 20, and the minimum voltage of the _{drive voltage V Dr.} _{The voltage value of the DC voltage V Offset} to be output from the output end of the multi-channel DAC 20 corresponding to the RTD oscillating element 50 to be operated is set so that the _{value is the bias voltage V NDR} 1 or less, which is the voltage value outside the terahertz wave oscillation region. Control.

The lower figure of FIG. 3 is a time chart showing the behavior of the terahertz wave generated from the RTD oscillator when the _{drive voltage V Dr is applied to the RTD oscillator.}

As shown in the upper part of FIG. 3, the RTD oscillator generates a terahertz wave only when _{the drive voltage V Dr} _{becomes a voltage value within the range of the bias voltage V NDR} 1 to V _NDR 2 which is the maximum value. Works on.

As a result, the terahertz wave of the RTD oscillating element to be operated can intermittently generate the terahertz wave in the period of the _{modulation voltage V AC.}

_{Next, a schematic time chart of the drive voltage V Dr} in the RTD oscillating element that does not generate the terahertz wave that is not the target of operation among the m RTD oscillating elements 50 and the terahertz wave output from the RTD oscillating element at that time is shown. Shown in 4.

The upper figure of FIG. 4 shows a time chart of the _{drive voltage V Dr} supplied to the RTD oscillator 50 that is not generated in the terahertz wave that is not the target of operation among the m RTD oscillators 50.

The control unit 10 corresponds to the RTD oscillating element to be operated with respect to the multi-channel DAC 20 so that the maximum value of the driving voltage V _Dr _{becomes the bias voltage VNDR} 1 or less which is the voltage value on the low voltage side of the terahertz wave oscillation region. Offset voltage at the output terminal V _Offset voltage value is set to 0V.

That is, as shown in the upper figure of FIG. 4, _{the maximum value of the drive voltage V Dr} does not reach the range of the _{bias voltage V NDR} 1 to V _NDR 2, which is the voltage value in the terahertz wave oscillation region.

The lower figure of FIG. 4 is a time chart showing the behavior of the terahertz wave generated from the RTD oscillator when the _{drive voltage V Dr is applied to the RTD oscillator.}

As shown in the upper figure of FIG. 4, since the _{bias voltage V NDR} 1 to V _NDR _{2 where the drive voltage V Dr} is the maximum value is not reached, the RTD oscillator does not generate a terahertz wave.

That is, according to the electromagnetic wave generator 1 of the present embodiment _{, among the drive voltage V Dr} applied to each of the RTD oscillators, m RTDs are controlled by controlling only the multi-channel DAC 20 that supplies the DC voltage component. It is possible to selectively generate a terahertz wave from an oscillating element.

According to this embodiment, it is possible to control one multi-channel DAC 20 and one high-speed DAC 30 to selectively operate m RTD oscillators 50, and it is possible to control the circuit of the IC chip including the DAC. Multi-element control of RTD oscillators corresponding to high modulation frequencies is possible without incurring large scale and high cost.

Further, according to this embodiment, by controlling only each voltage value of the _{DC offset voltage V Offset} 1 to V _Offset m output from the output end of the multi-channel DAC 20, the m RTD oscillators 50 Among them, it is possible to generate a terahertz wave only in a desired RTD oscillating element.

_{In the RTD oscillating element, V NDR} 1 and V _NDR 2, which are voltage values in the terahertz wave oscillation region, fluctuate depending on the composition type and individual differences. Therefore, the voltage value on the high-voltage side of the binary voltage value of the _{modulation voltage V AC} output from the high-speed DAC 30 is the highest of each of _{the low-voltage side voltage V NDR 1 in the terahertz wave generation region of the m RTD oscillators 50.} It is desirable to set the voltage value smaller than the small _{VNDR 1.}

_{In the description and drawings of this embodiment, the DC voltage V Offset} supplied by the multi-channel DAC 20 to the RTD oscillator that is not the target of operation is set to 0V, but the present invention is not limited to this. As the maximum value of the drive voltage V _Dr is less bias voltage V _NDR 1 on the low pressure side of the bias voltage V _{_NDR} 1 ~ V _NDR 2 as the voltage value of the terahertz wave oscillation region, multi-channel DAC20 operation outside the scope of It suffices if the voltage value of _{the DC offset voltage V Offset} output from the output end corresponding to the RTD oscillating element can be controlled.

Further, in the description and drawings of this embodiment, _{the low voltage side of the binary voltage value of the modulation voltage V AC} output by the high-speed DAC 30 is set to 0 V, but the present invention is not limited to this.

Further, in the description and drawings of this embodiment, the DC voltage V _Offset supplied to the RTD oscillating element is set to be less than the voltage V _NDR _{1, and the bias voltage V NDR} 1 _{in which V Offset} + V _AC is the voltage value in the terahertz wave oscillation region. Although _{it was set to be within the range of ~ VNDR} _{2, the DC voltage V Offset} supplied to the RTD oscillating element was set to the region where the RTD oscillating element with a bias voltage of V _NDR 2 or more did not oscillate, and _{the high voltage side of V AC} was 0 V, low voltage. The side may be −V _AC and V _Offset −V _AC may be controlled within the range of V _NDR 1 to V _{NDR 2.}

Further, in the description and drawings of this embodiment, the modulation voltage V _AC output by the high-speed DAC 30 has been described as a square wave, but the present invention is not limited to this.

The voltage value settings of the multi-channel DAC 20 and the high-speed DAC 30 may be set according to the time responsiveness of the voltage value change of each DAC.

Further, in this embodiment, the electromagnetic wave generator used in the terahertz wave measuring device has been described as an example. However, it is not limited to the generation of terahertz waves by the RTD oscillating element, and it can also be used for an element that operates according to a driving voltage whose voltage value changes at high speed.

10 Control unit 20 Multi-channel DAC
30 high-speed DAC
40 adder 50 m RTD oscillators

Claims

A plurality of electromagnetic wave generating elements, each of which generates an electromagnetic wave in response to the supply of a driving voltage,
A DC voltage source that variably generates a plurality of DC voltages corresponding to each of the plurality of electromagnetic wave generating elements,
A modulation voltage source that generates a modulation voltage in which the voltage value changes periodically between a predetermined binary voltage value in the plurality of electromagnetic wave generating elements,
A supply unit that adds each of the plurality of DC voltages and the modulation voltage and supplies them to each of the plurality of electromagnetic wave generating elements.
A control unit that controls the DC voltage source to change the voltage values of the plurality of DC voltages independently of each other.
An electromagnetic wave generator characterized by being equipped with.
The control unit controls each voltage value of the DC voltage supplied to the plurality of electromagnetic wave generating elements to generate the electromagnetic wave only in a desired electromagnetic wave generating element among the plurality of electromagnetic wave generating elements. The electromagnetic wave generator according to claim 1.
Claim 1 or 2 characterized in that the maximum voltage of the modulation voltage output by the modulation voltage source is smaller than the minimum operating voltage value of the electromagnetic wave generating element having the lowest operating voltage among the plurality of electromagnetic wave generating elements. The electromagnetic wave generator described in.
The control unit determines the drive voltage supplied to each of the electromagnetic wave generating elements among the plurality of electromagnetic wave generating elements, and the maximum voltage value is the maximum operating voltage and the minimum operating voltage of each electromagnetic wave generating element. Any of claims 1 to 3, wherein the DC voltage value is controlled so that the voltage value is between the two and the minimum voltage is lower than the minimum operating voltage of each electromagnetic wave generating element. The electromagnetic wave generator according to 1.
The control unit sets the drive voltage supplied to each of the electromagnetic wave generating elements that do not generate the electromagnetic waves among the plurality of electromagnetic wave generating elements to a voltage whose maximum voltage value is lower than the minimum operating voltage of each electromagnetic wave generating element. The electromagnetic wave generator according to any one of claims 1 to 4, wherein the DC voltage value is controlled so as to be a value.
The electromagnetic wave generator according to claim 1, wherein the electromagnetic wave is a terahertz wave.
The electromagnetic wave generator according to any one of claims 1 to 6, wherein the electromagnetic wave generating element is a resonance tunnel diode.