JP2014045565A - Switching type diode and high-frequency rectifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: A conventional high-frequency rectifier is composed of one schottky diode; therefore occurs a restriction on decreasing an on-resistance of the schottky diode and increasing a breakdown voltage and hence the efficiency of conversion from high frequency to direct current lowers.SOLUTION: The present invention is configured so that a high breakdown voltage diode with a high breakdown voltage and a low resistance diode with low on-resistance which has switching means for switching between conduction and non-conduction according to an applied voltage to the high breakdown voltage diode are used together, thus achieving a high breakdown voltage and a low on-resistance and high efficiency of conversion from high frequency into direct current.

Description

The present invention relates to high efficiency of a high frequency rectifier that converts alternating current or high frequency power into direct current power.

As a conventional high-frequency rectifier, there is a single shunt rectifier.

A single shunt rectifier has a Schottky diode having one end (for example, an anode) grounded (or connected to a reference potential), and the other end (for example, the cathode) of the Schottky diode and a signal source (or a receiving antenna). An input filter and an output filter between the other end and the load resistor are included.

  A radio frequency (RF) input from a signal source to a single shunt rectifier is input to a Schottky diode, which is a rectifier element, through an input filter, and becomes a direct current (DC: Direct Current) due to nonlinearity of the Schottky diode. Converted. Specifically, when a forward voltage is applied to the Schottky diode, the current enters a conducting state and a current flows.When a reverse voltage is applied, a non-conducting state in which the current does not easily flow is obtained. Harmonics are generated. The DC component and harmonics generated by the non-linearity of the Schottky diode are smoothed by the capacitor in the output filter, and the DC component is output.

  As described above, the radio frequency (RF) of the signal source is converted to direct current (DC). Such prior art is described in Non-Patent Document 1 below, for example.

J. O. McSpadden, L. Fan, and K. Chang, “Design and experiments of a high-conversion-efficiency 5.8-GHz rectenna”, IEEE Trans. MTT, vol.46 No.12 pp.2053-2060, Dec. 1998.

In order to obtain high-efficiency characteristics in a high-frequency rectifier, the resistance is small when the forward voltage is applied to the Schottky diode, which is the rectifying element, and the resistance is low when the reverse voltage is applied. It is important that is large.
However, the conventional high-frequency rectifier is composed of a single Schottky diode, which reduces the resistance (ON resistance) when one Schottky diode is conducting and improves the breakdown voltage related to the resistance when non-conducting. There was a limit to doing it. As a result, the conventional high-frequency rectifier has a problem that the conversion efficiency for converting from AC power to DC power, that is, the RF-DC conversion efficiency is lowered.
In addition, there is a similar problem in the configuration of a rectifier other than a single shunt rectifier (for example, a bridge rectifier).

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a rectifying element applicable to a high-frequency rectifier capable of obtaining high RF-DC conversion efficiency and a rectifier using the rectifying element. To do.

  The rectifying element of the present invention is a switching diode, wherein the switching diode includes a first circuit including a first diode, a second diode and a switching means including a switching means. A first circuit and a second circuit are connected in parallel, the first diode and the second diode are diodes having different characteristics, and a voltage applied to the first diode is forward. The switching means is switched between a conducting state and a non-conducting state depending on whether it is in the reverse direction. The high-frequency rectifier according to the present invention is characterized in that the switching diode is provided as a rectifying element.

  According to the switching type diode of the present invention, the characteristics of the first diode and the second diode can be adaptively switched according to the applied voltage, the on-resistance or the voltage threshold when conducting can be reduced, and when non-conducting The breakdown voltage can be increased. As a result, there is an effect that high RF-DC conversion efficiency can be achieved in the high-frequency rectifier including the switching diode.

The block diagram which shows the high frequency rectifier which concerns on Embodiment 1 of this invention. The basic operation | movement of the diode which concerns on Embodiment 1 of this invention. Basic operation of a diode when a bias of a DC voltage _VL is generated in the first embodiment of the present invention. Basic operation of a diode using switching means between the high voltage diode 2 and the low resistance diode 4 in the first embodiment of the present invention. The block diagram which shows the other high frequency rectifier which concerns on Embodiment 1 of this invention. The block diagram which shows the other high frequency rectifier which concerns on Embodiment 1 of this invention. The block diagram which shows the other high frequency rectifier which concerns on Embodiment 1 of this invention. The block diagram which shows the high frequency rectifier which concerns on Embodiment 2 of this invention. The block diagram which shows the other high frequency rectifier which concerns on Embodiment 2 of this invention. The block diagram which shows the other high frequency rectifier which concerns on Embodiment 2 of this invention. The block diagram which shows the high frequency rectifier which concerns on Embodiment 3 of this invention. The block diagram which shows the high frequency rectifier which concerns on Embodiment 4 of this invention. The figure which shows operation | movement of the diode which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a high-frequency rectifier according to Embodiment 1 of the present invention.

  In the figure, a high frequency rectifier 1 includes a first circuit 3 including a high voltage diode (first diode) 2, and a second circuit 6 (first diode) including a low resistance diode (second diode) 4 and switching means 5. The circuit 3 and the second circuit 6 are collectively referred to as a switching diode 7), an input filter 8 well known in the rectifier, and an output filter 9 well known in the rectifier. The first circuit 3 and the second circuit 6 constitute a switching diode and function as a rectifying element. Here, the high breakdown voltage diode 2 is a diode having a higher breakdown voltage in the non-conductive state than the low resistance diode 4, and the low resistance diode 4 is a diode having a lower resistance (ON resistance) when conducting than the high breakdown voltage diode 2. . One end (cathode) of the high breakdown voltage diode 2 and one end (cathode) of the low resistance diode 4 are grounded, and the other end (anode) of the low resistance diode 4 is connected to the other end (anode) of the high breakdown voltage diode 2 via the switching means 5. ), A common connection point 10 with the output terminal of the input filter 8 and the input terminal of the output filter 9. The input filter 8 is connected between the common connection point 10 and the signal source 11, and the output filter 9 is connected between the common connection point 10 and the load 12.

  Next, the operation will be described. The alternating current or high frequency (RF) supplied from the signal source 10 passes through the input filter 8, and the second circuit including the first circuit 3 including the high voltage diode 2, the low resistance diode 4 and the switching means 5. The connection point 10 of the circuit 6 is reached. The high frequency rectified by these diodes is smoothed by the output filter 9, and a DC component is taken out by the load 12.

FIG. 2 shows the basic operation of the diode. Here, the diode 20 may be either the high voltage diode 2 or the low resistance diode 4. In FIG. 2, Vd is a voltage applied to the diode 20, Id is a current flowing through the diode 20, Bv is a breakdown voltage, Vt is a threshold voltage, Rs is a resistance (ON resistance) during conduction, and Vin is an input voltage. The input voltage waveform 21 from the signal source 10 is a sine wave. When the applied voltage Vd to the diode 20 is positive, the diode 20 becomes conductive (ON), and when the applied voltage Vd is negative, the diode 20 becomes nonconductive (OFF). The characteristic of the diode at the time of conduction is represented by the on-resistance Rs and the threshold voltage Vt. As the applied voltage Vd increases, it approaches a current-voltage characteristic having a constant on-resistance Rs starting from the threshold voltage Vt. On the other hand, when the applied voltage Vd is negative, current hardly flows when the applied voltage Vd is between 0 and -Bv, but when the voltage is lower than the breakdown voltage -Bv, current flows rapidly through the diode 20. Due to the non-linearity of the diode, DC components and harmonics are generated. In an actual rectifier circuit, in addition to the input voltage from the signal source, a voltage including these DC components and harmonic components is applied to the diode. Is done.

In the present embodiment, the input voltage from the signal source 11 and the voltage of the DC component and the harmonic component generated by the nonlinearity of the diode are applied to the high voltage diode 2 or the connection point 10, and switching is performed when the applied voltage is positive. The means 5 is designed to be in an ON state, and when negative, the switching means 5 is designed to be in an OFF state. High RF-DC conversion efficiency is achieved by selectively using the high voltage diode 2 of the first circuit 3 and the low resistance diode 4 of the second circuit 6 according to the ON / OFF change of the switching means 5. Details will be described later.

FIG. 3 shows the basic operation of the high-frequency rectifier 1. In FIG. 3, Vd is an applied voltage at the connection point 9, Id is a current flowing through the diode, Bv is a breakdown voltage, Vt is a threshold voltage, Rs is a resistance during conduction (on-resistance), Vin is an input voltage, and V _L is Represents DC voltage. An input voltage waveform 22 and a rectified voltage waveform 23 indicate an input voltage waveform from a signal source applied to the connection point 9 and a voltage waveform after rectification, respectively. Here, the input voltage waveform 22 and the rectified voltage waveform 23 include the DC voltage _VL generated at the load 12.

In the high frequency rectifier 1, the impedance of the input filter 8 viewed from the connection point 10 is matched to the input wave (fundamental wave) from the signal source, opened to the odd harmonics except the fundamental wave, and even harmonics. It is designed to be a short circuit. The impedance of the output filter 9 viewed from the connection point 10 is open to the odd harmonics including the fundamental wave and shorted to the even harmonics. As a result, the rectified voltage waveform at the connection point 10 is only an odd-order harmonic due to the impedance condition described above, and thus becomes a rectangular wave. At this time, only even-order harmonic current flows to the output filter 9, and full-wave rectification occurs. By smoothing this full-wave rectified waveform by the output filter 9, direct current can be supplied to the load 12. The load 12 obtains a DC voltage _VL based on the DC smoothed by the output filter 9. Since the DC voltage V _L is a DC component at the connection point 10, the DC voltage V _L is applied to the first circuit 3 and the second circuit 6.
However, due to the influence of the DC voltage V _L, the time during which the input voltage and the rectified voltage are negative becomes more than a half cycle, and the OFF state of the diode is longer than the half cycle of the input frequency. Along with this, the input voltage and the rectified voltage reach the breakdown voltage −Bv, and a current starts to flow suddenly at the time of non-conduction where high resistance is desired, so that the RF-DC conversion efficiency is lowered.

FIG. 4 shows an operating state of a diode (switching diode) composed of the high voltage diode 2 and the low resistance diode 4 to which the switching means 5 is connected in the first embodiment. FIG. 4A shows current-voltage characteristics when the high voltage diode 2 is used alone, where Vd is a voltage applied to the diode, Ida is a current flowing through the diode, Bva is a breakdown voltage, and Vta is a threshold value. Voltage, Rsa is a resistance (ON resistance) when conducting, and Vin is an input voltage. FIG. 4B shows current-voltage characteristics when the low-resistance diode 4 is used alone, where Vd is a voltage applied to the diode, Idb is a current flowing through the diode, Bvb is a breakdown voltage, and Vtb is a threshold value. Voltage, Rsb is a resistance during conduction (on-resistance), and Vin is an input voltage. Here, Bva> Bvb and Rsa> Rsb. FIG. 4C shows the current-voltage characteristics of a diode (switching diode) composed of the high voltage diode 2 and the low resistance diode 4 to which the switching means 5 is connected. Vd is the voltage applied to the diode. , Id is the current through the diode, BVA the breakdown voltage, Vtb is the threshold voltage, Rsb resistance during conduction (oN resistance), the V _L represents a DC voltage obtained by rectifying.

In the switching diode 7 using the switching means, when the voltage applied to the high voltage diode 2 is negative, the switching means 5 is turned off. As a result, the rectifier circuit can increase the breakdown voltage Bv according to the characteristics of the high voltage diode 2. On the other hand, when the voltage applied to the high voltage diode 2 is positive, the switching means 5 is turned on, and a parallel circuit of the high voltage diode 2 and the low resistance diode 4 is formed. At this time, since the impedance of the low-resistance diode 4 is lower than that of the high-voltage diode 2, the total impedance in the ON state mainly depends on the impedance of the low-resistance diode 4. Based on such a principle, in the switching type diode using the switching means shown in FIG. 4C, the breakdown voltage becomes the breakdown voltage Bva of the high breakdown voltage diode 2, and the threshold voltage and the resistance at the time of conduction (ON resistance). Are the values Vtb and Rsb of the low resistance diode 4, respectively.

FIG. 4C shows a waveform 24 when only a high voltage diode is used and a waveform 25 when a switching means is used for a sine wave signal from a signal source. In the waveform 25 when the switching means is used, the voltage when the applied voltage is positive is smaller than the waveform 24 when only the high voltage diode is used due to the influence of the current flowing through the low resistance diode 4. That is, the waveform when in the non-conductive state depends on the characteristics of the high-voltage diode 2, and the waveform when in the conductive state depends on the characteristics of the low-resistance diode 4. As a result, the breakdown voltage Bv is large and the on-resistance Rs is small. From this, the resistance is small in the conductive state, and the resistance is large in the non-conductive state, so that high RF-DC conversion efficiency can be obtained.

  As described above, the high-frequency rectifier according to the first embodiment is switched between the input filter, the output filter, the first circuit including the high-voltage diode that is the first diode, and the low-resistance diode that is the second diode. And a second circuit including means, wherein one terminal of each of the first circuit and the second circuit is grounded, the other terminal of each of the first circuit and the second circuit, and an output terminal of the input filter And the input terminal of the output filter have a common connection point, and the switching means switches between a conducting state and a non-conducting state depending on whether the voltage applied to the first diode is in the forward direction or in the reverse direction. Therefore, high RF-DC conversion efficiency can be obtained.

  Further, although the low resistance diode 4 is a diode having a low resistance during conduction (on-resistance), a diode having a low threshold voltage Vt may be used. When the threshold voltage Vt is low, the low-resistance diode 4 becomes conductive at a low voltage, so that current easily flows during conduction. Therefore, since the combined on-resistance of the high-breakdown-voltage diode 2 and the low-resistance diode 4 is low, high RF-DC conversion efficiency can be obtained similarly. Further, it is obvious that the low resistance diode 4 may be a diode having a low resistance (ON resistance) when conducting and a low threshold voltage Vt.

  Further, the high voltage diode 2 may be a wide bandgap diode such as GaN (gallium nitride).

  The switching means 5 may be configured by a circuit that automatically switches on and off according to the voltage at the connection point 10 (voltage applied to the high voltage diode 2), and is controlled by a control signal to turn on and off. May be configured by a circuit that switches between. The control signal may be given in advance as data, or may be generated by monitoring the voltage applied to the diode. Details of this operation are disclosed in the second and third embodiments.

Further, as shown in FIGS. 5 and 6, the switching means 5 may be configured symmetrically with respect to the short-circuit point or the ground point so as to correspond to the differential input. Further, as shown in FIG. 7, in the bridge type rectifier, the same effect can be obtained by connecting the diodes using the switching means 5a, 5b, 5c, and 5d. Therefore, the rectifier other than the single-shunt rectifier may be a switching diode, and the configuration of this embodiment can be applied.

Embodiment 2. FIG.
FIG. 8 is a block diagram showing a high-frequency rectifier according to Embodiment 2 of the present invention.

  In the figure, the switching means 5 is constituted by a transistor 30, and a configuration using a p-channel MESFET (Metal-Semiconductor Field Effect Transistor) is disclosed as an example of the transistor 30. The gate terminal of the transistor 30 is grounded, the source terminal is the input terminal of the switching means 5 and is connected to the other end (anode) of the high voltage diode 2, and the drain terminal is the output terminal of the switching means 5 and the low resistance diode 4 Connected to the other end (anode). Other configurations are the same as those in FIG.

  Next, the operation will be described. The basic operation is the same as in the first embodiment. In addition to the first embodiment, the switching means 5 applies the same voltage as the voltage Vd applied to the high voltage diode 2 between the gate and the source. When a reverse voltage (Vd <0) is applied to the node 10 or the high voltage diode 2, the gate-source voltage Vgs is positive and the transistor 30 is non-conductive. On the other hand, when a forward voltage (Vd> 0) is applied to the node 10 or the high voltage diode 2, Vgs is negative and the transistor 30 becomes conductive.

  As described above, according to the second embodiment, by using a transistor as the switching unit 5, the switching state of the switching unit 5 can be smoothly switched between the conductive state and the non-conductive state according to the voltage Vd applied to the connection point 10. Is possible. As a result, high RF-DC conversion efficiency can be obtained.

  The transistor 30 may be a p-channel MOS type FET, HEMT, or junction type FET. As shown in FIG. 9, when the directions of the high voltage diode 2 and the low resistance diode 4 are reversed (the anode is grounded and the cathode is RF input), the transistor 30 may be an n-channel MESFET.

  8 and 9, the source terminal of the transistor 30 is connected to the high breakdown voltage diode as the input terminal of the switching means 5, and the drain terminal is connected to the low resistance diode 4. However, the source and drain are structurally Therefore, the connection between the source terminal and the drain terminal may be reversed as shown in FIG.

Embodiment 3 FIG.
FIG. 11 is a block diagram showing a high-frequency rectifier according to Embodiment 3 of the present invention.

  In the figure, the gate terminal of the transistor 30 is connected to the control circuit 31, and the transistor 30 is turned on / off by a signal from the control circuit 31. The other configuration is the same as that shown in FIG.

  Although the basic operation of the present embodiment is the same as that of the second embodiment, the gate terminal of the transistor 30 is connected to the control circuit 31, and the difference between the signal from the control circuit 31 and the voltage applied to the source is the difference. The transistor 30 is turned on / off according to a certain gate-source voltage Vgs. Therefore, the conduction / non-conduction state of the transistor 30 can be controlled by a signal from the control circuit 31. Specifically, when the gate-source voltage Vgs, which is the difference between the voltage Vd applied to the high voltage diode 2 and the control voltage from the control circuit 31, becomes positive, the transistor 30 becomes non-conductive. On the other hand, when a control voltage is applied from the control circuit 31 so that Vgs becomes negative, the transistor 30 becomes conductive.

  Next, the operation in this embodiment will be described. The basic operation is the same as in the first embodiment. In addition to the first embodiment, in the switching means 5, when a reverse voltage (Vd <0) is applied to the high breakdown voltage diode 2, the control voltage is supplied from the control circuit 31 so that the gate-source voltage Vgs becomes positive. give. As a result, the transistor 30 becomes non-conductive. On the other hand, when a forward voltage (Vd> 0) is applied to the high breakdown voltage diode 2, the transistor 30 becomes conductive by applying a control voltage from the control circuit 31 so that Vgs becomes negative.

  As described above, according to the third embodiment, the switching unit 5 is turned on / off by using a switching unit configured by a transistor whose conduction / non-conduction state is switched by applying a control voltage from the control circuit 31. The conduction state can be controlled by a control signal. As a result, high RF-DC conversion efficiency can be obtained. The control signal may be given in advance as data, or may be generated by monitoring an input wave.

  The low resistance diode 4 is a diode having a low resistance (ON resistance) when conducting, but may be a diode having a low threshold voltage Vt. The low resistance diode 4 may be a diode having a low resistance (ON resistance) when conducting and a low threshold voltage Vt.

Embodiment 4 FIG.
FIG. 12 is a block diagram showing a high-frequency rectifier according to Embodiment 4 of the present invention.

  In the figure, the high breakdown voltage diode 2 is composed of a series connection diode 40 in which N (integer) diodes are connected in series, and the low resistance diode 4 is composed of a parallel connection diode 41 in which M (integer) diodes are connected in parallel. The Other configurations are the same as those in FIG.

  Next, the operation will be described. The basic operation is the same as in the first embodiment. In addition to the first embodiment, since the series-connected diode 40 includes N diodes connected in series, the ON resistance Rs, the threshold voltage Vt, and the breakdown voltage Bv are each N times. On the other hand, since the parallel-connected diode 41 has M diodes connected in parallel, the on-resistance Rs of the diode is 1 / M times.

FIG. 13 shows an operating state of a diode (switching diode 7) composed of the high voltage diode 2 and the low resistance diode 4 to which the switching means 5 is connected in the present embodiment. As shown in FIG. 13A, since N high-voltage diodes are connected in series, the ON resistance Rs, the threshold voltage Vt, and the breakdown voltage Bv are each N times. On the other hand, as shown in FIG. 13B, M low-resistance diodes are connected in parallel, and the on-resistance Rs is 1 / M times. However, the threshold voltage Vt and the breakdown voltage Bv do not change.

Based on this configuration, the breakdown voltage N · Bv of the series-connected diode 40, the on-resistance Rs / M of the parallel-connected diode 41, and the threshold voltage Vt can be obtained as shown in FIG. As a result, the resistance is small when in a conducting state and the resistance is large when in a non-conducting state, so that high RF-DC conversion efficiency can be obtained.

  Further, in the present embodiment, the configuration in which the diode is changed to the series-connected diode and the parallel-connected diode is disclosed with respect to the first embodiment, but the diode is also connected to the series-connected diode and the parallel-connected to the second and third embodiments. You may change to a diode.

1: high frequency rectifier 2, 2a, 2b: high voltage diode 3: circuit 4, 4a, 4b: low resistance diode 5, 5a, 5b: switching means 6: circuit 7: switching diode 8: input filter 9: output filter 10 10a, 10b: Connection point 11: Signal source 12: Load 20: Transistor 21: Input voltage waveform 22: Input voltage waveform 23: Rectified voltage waveform 24: Waveform 25 using only a high voltage diode 25: Using switching means Waveform 26: When using only a series connection diode 27: Waveform when using switching means 30: Transistor 31: Control circuit 40: Series connection diode 41: Parallel connection diode

Claims (11)

A first circuit including a first diode;
A second diode having a second diode having different electrical characteristics from the first diode and a second circuit including switching means,
The first circuit and the second circuit are connected in parallel;
The switching unit switches whether to apply a voltage to the second diode according to whether a voltage applied to the first diode is in a forward direction or a reverse direction. Switchable diode. The first diode is a diode having a higher withstand voltage against a voltage applied in a reverse direction than the second diode,
2. The switchable diode according to claim 1, wherein the second diode has a lower resistance when conducting than the first diode, or is a diode through which current easily flows when conducting. A first circuit including a first diode;
A second circuit including a second diode and switching means connected in series with the second diode;
The first diode is a diode having a high withstand voltage with respect to a voltage applied in a reverse direction compared to the second diode;
The second diode is a diode having a low resistance when conducting compared to the first diode or a current easily flowing when conducting.
The switching means applies a voltage to the second diode when a forward voltage is applied to the first diode, and does not apply a voltage to the second diode when a reverse voltage is applied. A switchable diode. 4. The switching according to claim 1, wherein when the switching unit applies a voltage to the second diode, a forward voltage is applied to the second diode. 5. Diode.   5. The switchable diode according to claim 1, wherein the first diode includes one diode or a plurality of diodes connected in series. 6.   The switchable diode according to any one of claims 1 to 5, wherein the first diode is formed of a GaN diode.   The switchable diode according to any one of claims 1 to 6, wherein the second diode is configured by one or a plurality of diodes connected in parallel. The switching means is composed of a transistor,
The gate terminal of the transistor is grounded, one of the drain terminal and the source terminal of the transistor is an input terminal of the switching means, and the other is an output terminal of the switching means. 8. The switchable diode according to any one of 7 above. The switching means includes a transistor and a control circuit that outputs a switching voltage.
One of the drain terminal and the source terminal of the transistor is an input terminal of the switching means, and the other is an output terminal of the switching means,
The gate terminal of the transistor is connected to the output of the control circuit;
8. The switchable diode according to claim 1, wherein the transistor is switched between a conducting state and a non-conducting state according to a voltage output from the control circuit to the gate terminal. 9.   A high-frequency rectifier comprising the switching diode according to any one of claims 1 to 9 as a rectifying element.   The high-frequency rectifier according to claim 10, wherein the high-frequency rectifier is a single shunt rectifier or a bridge rectifier.

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