AC device

Abstract

Provided is an AC device in which the reflectance is reduced in a larger power range and frequency range. The AC device comprises: a transmission line having an output impedance of ZC, one endpoint of which is connected to an AC power supply; a plurality of phase shift circuits connected to the other end point of the transmission line; and an AC circuit connected to each phase shift circuit, the phase shift circuit being provided prior to the AC circuit serving as a load in each branch line, and each phase shift circuit having a phase shift angle and a characteristic impedance such that impedance matching is obtained for signals of a plurality of frequencies or a plurality of powers. The phase shift angle and the characteristic impedance are such that the real part of the composite admittance is 1 / ZC and the imaginary part of the composite admittance is zero when viewed from the other end point with respect to a plurality of conditions of the input signal.

Description

Technical Field

[0001] The present disclosure relates to AC devices. Background Art

[0002] Microwave antennas perform impedance matching by adjusting the size of the antenna or the power supply position so that reflection becomes zero at the desired frequency and the characteristic impedance of the signal source or transmission line, thereby efficiently sending signals into the air.

[0003] In addition, as electric vehicles and portable devices become more popular, the demand for contactless power supply that transmits power contactlessly is increasing. In contactless power supply using microwaves, a rectenna circuit is used, that is, a circuit that converts (rectifies) AC microwaves into DC.

[0004] In the rectifying antenna circuit that converts AC signals into DC signals, electric power is reflected between the signal source and the rectifying circuit. For antennas that emit radio waves into the air, reflection occurs at the interface between the signal cable and the antenna. Not only is the reflected power not used effectively, but if the reflected power returns to the power transmission device (power supply), it may also damage the power transmission device.

[0005] Generally, in order to prevent reflection, a matching circuit is arranged between devices where reflection occurs. It is known that by inserting a matching circuit, as long as the output impedance of the power transmission side device and the input impedance at the entrance of the matching circuit are in a complex conjugate relationship, reflection can be prevented and the maximum power can be supplied to the load (for example, Patent Document 1). In other words, in order to supply the maximum power to the load, the real value of the output impedance of the power supply and the input impedance of the load needs to be the same.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 5953603 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In a rectifier antenna circuit that rectifies high frequencies, the rectifier diode used for rectification has nonlinear characteristics with respect to input power. As a result, even if the rectifier antenna circuit is matched for a certain input power value, if the input power value changes, the input impedance changes, so reflection loss will still occur. Therefore, even if a matching circuit is used, the power range in which the rectifier antenna circuit can achieve high efficiency is still narrow. An AC circuit is required that can reduce reflectivity within a wider power range and perform efficient AC-DC conversion in an environment where transmission conditions are unstable, such as wireless power transmission.

[0011] In addition, since the antenna utilizes resonance within the antenna member, the frequency band in which transmission can be performed efficiently is narrow and limited to one frequency. Therefore, an antenna that can support a wider band or multiple frequencies is required.

[0012] An object of the present invention is to provide an AC circuit which prevents reflections over a wider power range.

[0013] Solutions to the problem

[0014] In one embodiment of the present disclosure, an AC device includes: an output impedance of Z C A transmission line, one end of which is connected to an AC power source; a plurality of phase shifting circuits connected to the other end of the transmission line; and an AC circuit connected to each phase shifting circuit, each phase shifting circuit having a plurality of conditions for the input signal so that the real part of the synthetic admittance viewed from the other end is 1 / Z C The phase shift angle and characteristic impedance with zero imaginary part.

[0015] Effects of the Invention

[0016] According to the present disclosure, the rectenna circuit can reduce reflectivity in a wider power range. In addition, the antenna can efficiently emit radio waves at multiple frequencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram showing a circuit for transmitting power from a power supply to a load using a rectifier circuit.

[0018] Figure 2 This is a diagram showing a circuit in which a matching circuit and a rectifying antenna using a harmonic cut filter are connected to transmit power from a power supply to a load.

[0019] Figure 3 This is a diagram showing a circuit in which an input transmission path is branched at a branch point and AC circuits are connected in parallel.

[0020] Figure 4 This is a diagram showing an example of an AC circuit serving as a load.

[0021] Figure 5 It is a Smith chart notation-based graphic representation of reflected waves from an AC circuit.

[0022] Figure 6 This is a diagram showing an example in which a matching circuit is connected between an input and a branch point.

[0023] Figure 7 This is a diagram showing a circuit in which an input transmission path is branched into a first line and a second line at a branch point, and a phase shifting circuit is connected to the input of an AC circuit of each line.

[0024] Figure 8 FIG. 1 is a diagram showing a rectifier circuit which is a basic part of a rectenna circuit.

[0025] Fig. 9 This is a diagram showing a rectifying antenna circuit in which an LPF is added to the basic part.

[0026] Fig.10 This is a diagram showing a rectifying antenna circuit in which an LPF and a matching circuit are added to the basic part.

[0027] Fig.11 It is a graph showing the RF / DC conversion efficiency and reflectivity of the rectenna circuit with respect to input power.

[0028] Fig.12 This is a diagram showing a circuit for suppressing reflection in a rectifying antenna circuit by utilizing a phase difference of reflected waves between lines.

[0029] Fig.13 It is a Smith chart representation of the reflected wave corresponding to the input signal.

[0030] Fig.14 This is a diagram showing an example in which a plurality of antennas are connected in parallel.

[0031] Fig.15 It is a diagram showing the reflection characteristics of the antenna with respect to the input signal.

[0032] Fig.16 is a Smith chart illustrating impedance matching.

[0033] Fig.17 This is a diagram showing an example in which input branches are superimposed in multiple stages.

[0034] Fig.18 This is a diagram showing an example in which a plurality of antennas are connected in parallel and a phase shifting circuit is provided at the input of each line.

[0035] Fig.19 This is the reflectivity when impedance matching is performed at four frequencies.

[0036] Fig. 20 This is a diagram showing an example in which a plurality of rectifier circuits are connected in parallel and a phase shift circuit is provided at the input of each rectifier circuit.

[0037] Fig.21 This is a diagram showing the RF / DC conversion efficiency and reflectivity when branching into a plurality of lines.

[0038] Fig. 22 This is a diagram showing the admittance at the branch point using complex notation when the power of the input signal of each line is changed within a range of 0.1 to 50 W.

[0039] Fig.23 FIG. 1 is a diagram showing a rectifying antenna circuit using a matching circuit formed of an LC circuit.

[0040] Fig.24 1 is a diagram showing a circuit using an LC circuit as a phase shifting circuit of a parallel-connected rectifying antenna circuit.

[0041] Fig.25 It is a graph showing the RF / DC conversion efficiency and reflectivity when the input power changes.

[0042] Description of Reference Numerals

[0043] 111, 1211, 1411, 1711, 1811, 2011, 2311 power supply

[0044] 112 Oscillator

[0045] 113 Power supply resistor

[0046] 120, 820, 2320 rectifier circuit

[0047] 122, 2322DC cut-off capacitor

[0048] 612, 2326c capacitors for matching circuits

[0049] 2410b, 2420b capacitors for phase shift circuits

[0050] 611, 2326a, 2326b matching circuit inductors

[0051] 2410a, 2420a Inductors for Phase Shift Circuits

[0052] 123, 124, 823, 824, 2323, 2324 diodes

[0053] 130 load

[0054] 220, 1020, 2340 rectifier antenna circuit

[0055] 226, 610, 1026, 2326 matching circuits

[0056] 227, 927 harmonic cutoff filter (LPF)

[0057] 310 input terminal

[0058] 320, 1730, 1820, 2020 branch points

[0059] 330, 1740, 1830, 2030 input transmission path

[0060] 340, 350 AC circuit

[0061] 710, 720, 1210, 1220, 1410, 1420, 1710, 1720, 2410, 2420 phase shift circuit

[0062] Lines 730, 740, 1230, 1240, 2430, 2440

[0063] 1430, 1440 antenna DETAILED DESCRIPTION

[0064] As described below, in the AC circuit of the present disclosure, reflection can be suppressed for a plurality of conditions, which are conditions of an input signal, simply by adjusting the phase shift angle of the phase shift circuit.

[0065] The rectenna circuit can suppress reflections over a wide range of input power or frequency by combining it with a matching circuit, maintaining high RF / DC (Radio Frequency / Direct Current) conversion efficiency. In addition, when used as an antenna, it can radiate signals in multiple bands.

[0066] Alternatively, by arranging multiple bands in close proximity, the radiation band can be made wider.

[0067] (Rectenna)

[0068] Before describing the present invention in detail, problems in the rectifier circuit will be described first.

[0069] Figure 1 This is a diagram showing a circuit for transmitting power from a power supply to a load using a rectifier circuit.

[0070] Figure 1 The circuit shown has a power supply 111, a capacitor 122, a rectifier circuit 120 and a load 130. The load may be a constant voltage load, a constant resistance load or other types of loads.

[0071] The power source 111 can be understood as an equivalent circuit including an oscillator 112 and a power source resistor 113 .

[0072] The power source 111 generates microwaves for power transmission. The frequency of the microwaves generated by the power source 111 is, for example, 5.8 GHz. In wireless power transmission, the power source serves as a power receiving antenna.

[0073] The rectifier circuit 120 includes a diode 123 and a diode 124. The anode of the diode 123 is grounded. The cathode of the diode 124 is connected to one end of a load 130. The other end of the load 130 is grounded. The load 130 is a constant resistance load or a constant voltage load. In either case, a constant voltage is required between the cathode of the diode 124 and the ground. Therefore, in the case other than the constant voltage load, a smoothing circuit using a capacitor or a stub is connected here.

[0074] One end of the capacitor 122 is connected to the power supply 111, and the other end of the capacitor 122 is connected to the connection point of the cathode of the diode 123 and the anode of the diode 124 of the rectifier circuit 120. In the rectifier circuit, although a DC voltage is generated due to signal conversion, the capacitor 122 is inserted to separate the DC voltage on the signal source side and in the rectifying antenna circuit, and has a sufficiently large value that does not affect the AC characteristics.

[0075] Figure 1 The rectifier circuit 120 is called a "voltage doubler circuit".

[0076] It is also possible to use a single shunt circuit using one diode and a λ / 4 line as the rectifying circuit 120 .

[0077] If a microwave signal is input to the rectifier circuit 120, it will be reflected at the connection point of the cathode of the diode 123 and the anode of the diode 124. From the perspective of the power transmission device, the rectifier circuit using the diode appears to be a parallel connection of the capacitance when the diode 123 is disconnected, the capacitance when the diode 124 is disconnected, and the effective resistance of the load 130. The effective resistance value when the load is a constant voltage power supply is determined by the voltage of the power supply and the current flowing in. Due to the complex impedance caused by the parallel connection of the capacitor and the resistor, there is a mismatch with the impedance of the input transmission path, resulting in reflection. For the rectenna circuit, reflection is a loss.

[0078] Figure 2 The diagram shows a circuit in which a rectifying antenna circuit 220 using a matching circuit 226 and a harmonic cutoff or low-pass filter 227 (LPF: Low-pass Filter) is connected to transmit power from a power supply 111 to a load 130 .

[0079] One end of the matching circuit 226 is connected to the other end of the capacitor 122 , and the other end of the matching circuit 226 is connected to one end of the LPF 227 .

[0080] The other end of the LPF 227 is connected to the cathode of the diode 123 and the anode of the diode 124 .

[0081] In order to prevent reflection, a matching circuit is generally used in a high-frequency circuit to suppress reflection and prevent a decrease in efficiency. Therefore, a matching circuit 226 is connected.

[0082] In addition, the diode has a nonlinear characteristic with respect to the input voltage, so even if a sinusoidal AC signal is input, the reflected wave will still contain the harmonics of the input signal. The reflection of the harmonics is also a loss, so LPF227 is connected to trap the harmonics generated inside and prevent the harmonics from being emitted as reflected waves. Therefore, from the perspective of the matching circuit 226, the reflected wave is only the fundamental wave, so Figure 2 The circuit can achieve impedance matching.

[0083] When the load 130 is a constant voltage load, the current flowing to the load changes due to the input power, so if the load is regarded as a resistor, the effective resistance value changes due to the power. When the load 130 is a constant resistance load, although the resistance value does not change, the output DC voltage changes due to the input power. As a result, when the diode is turned off, the average voltage applied to the diode changes, and the depletion layer capacitance changes.

[0084] That is, when the input power changes, the input impedance of the rectenna circuit changes regardless of whether it is a constant voltage load or a constant resistance load. This means that even if matching is performed under a certain input condition to make reflection zero, reflection will still occur if the input power changes. As a result, a high efficiency state with low reflectivity can be achieved only within a narrow range of input conditions after impedance matching.

[0085] (First Embodiment: Branching of Lines in RC Circuit)

[0086] Here, a method of suppressing reflections in an AC circuit by using line branching and a phase shifting circuit, which is the subject of the present invention, is described using an example of a simple circuit.

[0087] If a sine wave is input to an AC circuit, the AC circuit will reflect the input signal due to its characteristics.

[0088] In the case where the reflected wave is only the fundamental wave, the reflection can be suppressed by controlling the amplitude and phase of the reflected wave of the capacitor and inductor, or the impedance line of finite length and the short stub, etc. However, in the case where an AC circuit can be formed by connecting two circuits in parallel, the reflection can be suppressed by inserting a phase shifting circuit in each of the two circuits to control the phase shift delay (phase shift angle) without using a matching circuit.

[0089] Hereinafter, a circuit will be described which branches input power to two lines at a branch point and suppresses reflection by utilizing a phase difference of reflected waves between the lines without using a matching circuit.

[0090] Figure 31 is a diagram showing a circuit in which an input transmission path 330 connected to an input terminal 310 is branched at a branch point 320 so that an AC circuit A 340 and an AC circuit B 350 are connected in parallel.

[0091] Figure 4 It means in Figure 3 1 is a diagram showing an example of an AC circuit that serves as a load in FIG. The AC circuit is composed of, for example, a circuit in which a resistor and a capacitor are connected in parallel.

[0092] Figure 5 For the direction Figure 3 and Figure 4 A Smith chart diagram of the reflected wave of a signal in a circuit. The normalized impedance is 50Ω.

[0093] Assumptions Figure 3 The AC circuit A340 is composed of, for example, a 240Ω resistor and a 100pF capacitor connected in parallel. When a signal with a frequency of 10 MHz is applied to the circuit from a signal source with a characteristic impedance of 50Ω, the reflection coefficient is given by Figure 5 The reflection coefficient 510 is represented by the white circle in the Smith chart.

[0094] Assumptions Figure 3 The AC circuit B 350 is composed of, for example, a 40Ω resistor and a 200pF capacitor connected in parallel. When a signal with a frequency of 10 MHz is applied to the circuit from a signal source with a characteristic impedance of 50Ω, the reflection coefficient is given by Figure 5 The reflection coefficient of the white square in the Smith chart is 520.

[0095] In addition, a signal with a frequency of 10 MHz is applied from a signal source with a characteristic impedance of 50 Ω to the Figure 3 In the case of a circuit in which AC circuit A 340 and AC circuit B 350 are connected in parallel, the reflection coefficient is given by Figure 5 The reflection coefficient 530 of the black triangle in the Smith chart is represented.

[0096] like Figure 5 As shown, neither of the above circuits matches the signal source with a characteristic impedance of 50Ω.

[0097] In the past, for example Figure 3 A matching circuit is connected between the input terminal 310 and the branch point 320 to perform impedance matching. Figure 6 1 is a diagram showing an example in which a matching circuit 610 is connected between the input terminal 310 and the branch point 320 .

[0098] The matching circuit 610 is composed of an inductor 611 and a capacitor 612. Figure 6In the case of impedance matching of the input terminal 310 with an impedance of 50Ω at a frequency of 10 MHz, by using an inductor 611 of 647 nH (L=647 nH) and a capacitor 612 of 329 pF (C=329 pF), the coordinates of the reflected wave viewed from the input terminal 310 can be made the origin 560, thereby eliminating reflection.

[0099] In such Figure 3 When two AC circuits are connected in parallel as described, reflection will not occur as long as the inverse of the composite admittance viewed from the branch point 320 is in a complex conjugate relationship with the signal source impedance. In other words, the real part of the composite admittance can be set to the inverse of the signal source impedance, i.e., 20 mS, and the imaginary part can be set to zero.

[0100] This can also be achieved by connecting a phase shift circuit to the input of each AC circuit. Each "series of circuits" branched from the branch point 320 and connected in parallel is referred to as a "line".

[0101] Figure 7 3 is a diagram showing a circuit in which an input transmission path 330 branches into a first line 730 and a second line 740 at a branch point 320, in which a phase shift circuit A 710 is connected to the input of an AC circuit A 340 in the first line 730, and in which a phase shift circuit B 720 is connected to the input of an AC circuit B 350 in the second line 740.

[0102] The reflected wave returning to the branch point 320 from the first line 730 and the second line 740 is a synthesis of the reflected waves from each line. The signal frequency of the reflected wave is the same as that of the incident wave, so the synthesized reflected wave can be uniquely represented by two parameters: amplitude and phase difference relative to the input signal. In other words, in order to perform impedance matching, it is only necessary to optimize the two parameters of amplitude and phase difference relative to the input signal.

[0103] Each phase shift circuit has two parameters, characteristic impedance and phase shift angle, so there are four parameters for the two phase shift circuits as a whole. Here, it is assumed that the characteristic impedance is fixed to 50Ω, and matching is performed by adjusting the phase shift angle of each phase shift circuit.

[0104] exist Figure 5 In the Smith chart, the change in the coordinates (reflection coefficient) of the reflected wave caused by the phase shift circuit with a characteristic impedance of 50Ω becomes a movement on a circle centered on the origin.

[0105] When the phase shift angle of the phase shift circuit A710 is set to 135.5 degrees, the reflected wave moves from the reflection coefficient 510 to the reflection coefficient 540. The reflection coefficient 540 is a reflection corresponding to a load having an admittance of (0.00467-j0.0095)S.

[0106] If the phase shift angle of the phase shift circuit B 720 is set to 155.8 degrees, the reflected wave moves from the reflection coefficient 520 to the reflection coefficient 550. The reflection coefficient 550 is a reflection corresponding to a load having an admittance of (0.01533+j0.0095)S.

[0107] The synthetic admittance viewed from the branch point 320 is the sum of the two admittances, that is, (0.02+j0)S, and therefore can be matched with a signal source having a characteristic impedance of 50Ω.

[0108] The adjustment range of admittance is limited by the original impedance value, so it may not always be possible to adjust, but it can be accurately adjusted within the adjustable range. When matching is performed in this way, although reflections are caused in the first line 730 and the second line 740 connected to the branch point 320, the reflections stay in each line and do not go out of the branch point 320 (to the input transmission path 330 side).

[0109] (Second Embodiment: Rectenna Circuit)

[0110] An example is described below, which is an example of applying the principle of the present invention to the reflection suppression of the rectifying antenna circuit described above.

[0111] Hereinafter, reflection suppression of a rectenna circuit using a Schottky barrier diode (SBD: Schottky Barrier Diode) using gallium nitride (GaN) as a diode will be described.

[0112] Figure 8 to Figure 10 This is a diagram showing a rectifying antenna circuit used in the calculation. Figure 8 FIG. 1 is a diagram showing a rectifier circuit which is a basic part of a rectenna circuit. Fig. 9 This is a diagram showing a rectifying antenna circuit in which LPF927 is added in addition to the basic part. Fig.10 This is a diagram showing a rectifying antenna circuit to which LPF 927 and matching circuit 1026 are newly added in addition to the basic parts.

[0113] The output of the power supply 111 is connected to one end of the capacitor 122. The other end of the capacitor 122 is connected to the cathode of the SBD 823 and the anode of the SBD 824. The signal source and the DC voltage of the rectifying antenna circuit can be separated by the capacitor 122. The anode of the SBD 823 is grounded. The cathode of the SBD 824 is connected to the load 130.

[0114] SBD823 and SBD824 constitute a rectifier circuit 820 .

[0115] Both SBD823 and SBD824 use 16 4μm diameter dot (small circle) diodes connected in parallel. The capacitance of one dot when disconnected is 0.03pF, and the resistance when connected is 26Ω. Due to the limitation of withstand voltage, the constant voltage load is 60V.

[0116] Fig. 9 The rectifier circuit 920 is formed by connecting the LPF 927 to the rectifier circuit 820. The SBD 823 and the SBD 824 are connected to the Figure 8 same.

[0117] LPF927 is made of a 50Ω microstrip line on a substrate with a relative dielectric constant of 4.2. The frequency of microwaves is 5.8 GHz, and the wavelength of the signal in the microstrip line on the substrate is about 28 mm. LPF927 is composed of a third harmonic cutoff filter (BEF: Band Elimination Filter) 927a and a fifth harmonic BEF927b.

[0118] BEF927a is an open stub of a microstrip line with L=2.1 mm (0.083λ=1 / 12λ). BEF927b is an open stub of a microstrip line with 1.26 mm (0.05λ=1 / 20λ). BEF927a and BEF927b are both connected to the other end of capacitor 122, the cathode of SBD823, and the anode of SBD824.

[0119] In addition, LPF927 can be a filter that removes only the third harmonic, or a filter that removes harmonics exceeding the fifth order. In addition, LPF927 can also be made using other structures. In the case of low frequency, LPF using an LC circuit can also be used instead of BEF927a and BEF927b.

[0120] Fig.10 The rectenna circuit 1020 is formed by connecting the matching circuit 1026 to the rectifier circuit 920. SBD823, SBD824 and LPF927 are connected to Fig. 9 same.

[0121] The matching circuit 1026 is composed of a microstrip line 1026a and a microstrip line 1026b connected in series. The matching circuit 1026 may also be made using other structures.

[0122] One end of the microstrip line 1026 a is connected to the other end of the capacitor 122 and the microstrip line 1026 b , and the other end of the microstrip line 1026 a is connected to the cathode of the SBD 823 , the anode of the SBD 824 , the BEF 927 a , and the BEF 927 b .

[0123] Here, a line with L=0.153λ is used as the microstrip line 1026a, and a short stub line with L=0.195λ is used as the microstrip line 1026b, so that the input power Pin is matched to 3W. Fig.11 Yes means Fig.10 A graph showing the circuit's RF / DC conversion (conversion from microwave power to DC power) efficiency for input power and the reflectivity toward the input side. Fig.11 Line 1110 represents the RF / DC conversion efficiency, and line 1120 represents the reflectivity (power reflectivity). When Pin = 3W, the reflectivity is 0, and the RF / DC conversion efficiency reaches the maximum. However, the RF / DC conversion efficiency is high (for example, more than 90%) only when the power of the input signal is in the range of 2.5 to 4W.

[0124] Fig.12 This is a diagram showing a circuit that divides the input into two lines and uses the phase difference of the reflected wave between the lines to suppress reflection. Fig.12 In the example, each line includes a matching circuit, and when Pin=3W, reflection is suppressed by the effect of the matching circuit.

[0125] The input transmission path 330 has a characteristic impedance of 25Ω, and the first line 1230 and the second line 1240 have a characteristic impedance of 50Ω.

[0126] The input transmission path 330 includes a power source 1211 and a capacitor 122 . One end of the capacitor 122 is connected to the output of the power source 1211 , and the other end of the capacitor 122 is connected to the branch point 320 .

[0127] The first circuit 1230 includes a phase shift circuit 1210 and a rectifying antenna circuit 1020a. Fig.10 The rectenna circuit 1020 is the same.

[0128] The second circuit 1240 has a phase shift circuit 1220 and a rectifying antenna circuit 1020b. The rectifying antenna circuit 1020b is the same as the rectifying antenna circuit 1020a.

[0129] The branch point 320 , the phase shift circuit 1210 , the rectenna circuit 1020 a , the phase shift circuit 1220 , and the rectenna circuit 1020 b constitute a rectenna circuit 1250 .

[0130] The output impedance of the power supply 1211 is 25Ω.

[0131] When 6W of power is output from the power source 1211, 3W of power is input to the first line 1230 and the second line 1240, respectively. Fig.10As described above, for an input power of 3 W, the rectifying antenna circuit 1020 a and the rectifying antenna circuit 1020 b are matched, and no reflection occurs regardless of the phase shift amount of the phase shift circuit.

[0132] On the other hand, consider the case where 20 W of power is output from the power supply 1211. In this case, if there is no reflection in the transmission path, 10 W of power is input to each of the first line 1230 and the second line 1240, but since the matching circuit 1026 is matched for 3 W, reflection occurs. Therefore, when 10 W of power is input, the phase shift amounts of the phase shift circuit 1210 of the first line 1230 and the phase shift circuit 1220 of the second line 1240 are adjusted so that the combined impedance of the first line 1230 and the second line 1240 becomes an impedance of only the real part 25Ω.

[0133] The adjustment of the phase shift circuit 1210 and the phase shift circuit 1220 is described using a Smith chart.

[0134] Fig.13 is with Fig.12 Illustration of the reflected wave corresponding to the input signal of the circuit based on the Smith chart notation.

[0135] Fig.12 The circuit of is matched when the input power is 3W, so the coordinates when the input power is 3W become the origin 1310. Next, consider that a power of 10W is input to the rectenna circuit 1020a and the rectenna circuit 1020b. Fig.12 The two rectifier circuits are matched for Pin = 3W, so reflection occurs in the case of 10W. If the reflectivity at this time is considered, the reflection coefficient when 10W is input into the rectifier circuit is equivalent to the case when 13.55W is input from the outside. The reflection coefficient in this case is 1320.

[0136] If the phase shift circuits 1210 and 1220 are used to move the reflection coefficient 1320 to the reflection coefficient 1330 and the reflection coefficient 1340 on the isoelectric conductivity circle of 50Ω, the imaginary parts of the impedance cancel each other, and the composite impedance becomes 25Ω with only the real part. As a result, it is equal to the impedance 25Ω of the input transmission path 330, so that reflection can be suppressed. If the phase shift angle in the phase shift circuit 1210 is set to 55.44 degrees, the reflection coefficient 1320 will move to the reflection coefficient 1330, and if the phase shift angle in the phase shift circuit 1220 is set to 175.58 degrees, the reflection coefficient 1320 will move to the reflection coefficient 1340.

[0137] about Fig.12 The circuit, Fig.11Line 1130 represents the RF / DC conversion efficiency for the input power, and line 1140 represents the reflectivity for the input power. Here, the horizontal axis represents the input power to the unit line, and the output power of the power supply with two lines is twice the power. Fig.21 , Fig.25 The same is true in . Between Pin=3W and 10W, the reflectivity shown by line 1140 is close to zero, and the RF / DC conversion efficiency shown by line 1130 is maintained at a value of more than 90% between 1.7W and 13W.

[0138] express Fig.12 Line 1130 of the RF / DC conversion efficiency of the circuit maintains high efficiency over a wider range of input power compared to line 1110 in the case of a single line. This means that even if the power of the input signal changes greatly, high-efficiency RF / DC conversion is performed, which is particularly beneficial for wireless power transmission, etc., where transmission power fluctuations are prone to occur.

[0139] (Third Embodiment: Antenna)

[0140] Next, a case where the principle of the present invention is applied to an antenna circuit will be described.

[0141] Fig.14 1 is a diagram showing an example of connecting a plurality of antennas in parallel. The following describes matching when the frequency of an input signal changes.

[0142] The power source 1411 is connected to the input terminal 310, and the antenna A 1430 and the antenna B 1440 are connected in parallel to the branch point 320 via the phase shift circuit A 1410 and the phase shift circuit B 1420, respectively. It is assumed that the antenna A 1430 and the antenna B 1440 have the same characteristics.

[0143] For example, the antenna is a patch antenna having a characteristic impedance of 50Ω, and is an antenna that does not reflect when an input signal frequency is 2.45 GHz, that is, sufficiently radiates radio waves.

[0144] Fig.15 15 is a graph showing the reflection characteristics of an antenna with respect to the frequency of an input signal. Line 1510 shows the reflectivity of an individual antenna with respect to an input signal. Line 1510 shows the case where the reflectivity is 0 for 2.45 GHz, at which frequency the input signal is completely emitted from the antenna.

[0145] like Fig.14As shown in FIG. 1 , if a phase shift circuit is connected to the input of each antenna and the characteristic impedance of each phase shift circuit is set to 50Ω, which is the same as the characteristic impedance of the antenna, the combined impedance at the branch point 320 becomes 25Ω. Furthermore, by setting the characteristic impedance of the input transmission path 330 from the input terminal 310 to the branch point 320 to 25Ω, impedance matching is achieved at the branch point 320, so that no reflection occurs at the branch point 320. When the input signal is 2.45 GHz, no reflection occurs at the antenna part, so no reflection occurs as a whole.

[0146] Although impedance matching is performed for the antenna when the input signal is 2.45 GHz, matching for other frequency conditions can be performed using the phase shift angle in each phase shift circuit. For example, matching for an input signal of 2.40 GHz can also be achieved.

[0147] use Fig.16 The Smith chart shows the impedance matching achieved at 2.40 GHz using a phase shifting circuit.

[0148] The two antennas do not reflect at 2.45 GHz, so the reflection coefficient of each antenna when the input signal is 2.45 GHz is the origin 1610. On the other hand, when the input signal is 2.40 GHz, the reflection coefficient of the two antennas moves to 1620 due to the change in input frequency.

[0149] If a phase shift circuit with a characteristic impedance of 50Ω is connected to the antenna, the reflection coefficient will move on a circle centered at the origin. For example, if the phase shift angle of phase shift circuit A 1410 is set to 36.4 degrees, the reflection coefficient 1620 will move to 1630. If the phase shift angle of phase shift circuit B 1420 is set to 64.65 degrees, the reflection coefficient 1620 will move to 1640.

[0150] Because the reflected wave passes through the phase shift circuit twice, the shift on the Smith chart corresponds to twice the phase shift angle brought by the phase shift circuit. Both the reflection coefficient 1630 and the reflection coefficient 1640 exist on the isoelectric conductivity circle with an admittance of 20 mS. Moreover, the absolute values ​​of the imaginary parts of the reflection coefficient 1630 and the reflection coefficient 1640 are the same, but the positive and negative signs are opposite.

[0151] Thus, the real part of the synthetic admittance viewed from the branch point 320 is 40 mS, and the imaginary part is 0. This indicates impedance matching when the input signal line is 25Ω.

[0152] Since matching is achieved at 2.45 GHz regardless of the phase shift circuit, it is possible to form a circuit that does not cause reflection at both frequencies of 2.40 GHz and 2.45 GHz. Fig.15 Line 1520 represents this reflection characteristic.

[0153] As the second matching condition, Fig.15 Line 1530 shows the reflection characteristics when the input signal is set to 2.449 GHz which is substantially equal to 2.45 GHz. Referring to line 1530, it can be seen that although the center frequency is substantially the same as line 1510 in the case of a single antenna, which is 2.45 GHz, the bandwidth is expanded.

[0154] It should be noted that due to the phase shift circuit, the phases of the signals radiated from the two antennas are different, which may cause interference, and the antennas may have complex directivity depending on the distance and direction between the antennas. Depending on the application, the directivity of the antenna may be an advantage or a disadvantage.

[0155] (Fourth Embodiment: Multi-stage Superposition)

[0156] The reflection suppression circuit branched into two lines can be superimposed in multiple stages. Here, the rectenna circuit is used as an example for explanation again.

[0157] exist Fig.12 In the rectenna circuits 1020a and 1020b that suppress reflection for an input power of 3 W, by using the phase shift circuits 1210 and 1220, reflection can be suppressed even for an input power of 10 W.

[0158] Fig.17 It means to further combine the two Fig.12 The circuit of is combined with the circuit diagram of .

[0159] The input transmission path 1740 has a characteristic impedance of 12.5Ω, and the first line 330a and the second line 330b have a characteristic impedance of 25Ω.

[0160] The input transmission path 1740 includes a power source 1711 and a capacitor 122 . One end of the capacitor 122 is connected to the output of the power source 1711 , and the other end of the capacitor 122 is connected to the branch point 1730 .

[0161] The first line 330a includes a phase shift circuit 1710 and a rectifying antenna circuit 1250a. One end of the phase shift circuit 1710 is connected to the branch point 1730, and the other end of the phase shift circuit 1710 is connected to the rectifying antenna circuit 1250a. Fig.12 The rectenna circuit 1250 is the same.

[0162] The second line 330b has a phase shift circuit 1720 and a rectifying antenna circuit 1250b. One end of the phase shift circuit 1720 is connected to the branch point 1730, and the other end of the phase shift circuit 1420 is connected to the rectifying antenna circuit 1250b. The rectifying antenna circuit 1250b is the same as the rectifying antenna circuit 1250a.

[0163] The branch point 1730 branches the input transmission path 1740 into a first line 330a and a second line 330b.

[0164] If through Fig.12 As described above, for an input power of 6 W or 20 W, the rectifying antenna circuit 1250 a and the rectifying antenna circuit 1250 b are matched, and therefore, no reflection occurs regardless of the phase shift amounts of the phase shifting circuits 1710 and 1720 .

[0165] On the other hand, when the power supply 1711 outputs 4W of power, 2W of power is input to the first line 330a and the second line 330b, respectively, and reflections from the rectifying antenna circuit 1250a and the rectifying antenna circuit 1250b occur. Therefore, when the power supply 1711 outputs 4W of power, that is, when 1W of power is input to the unit rectifying circuit, the phase shift angles of the phase shift circuit 1710 of the first line 330a and the phase shift circuit 1720 of the second line 330b are adjusted so that the combined impedance of the first line 330a and the second line 330b observed at the branch point 1730 becomes 12.5Ω with only the real part.

[0166] When the input power of the unit rectifier circuit is 1 W, in order to make the real part of the impedance equal and the absolute value of the imaginary part of the impedance the same, the phase shift angle in the phase shift circuit 1710 is set to 57.6 degrees, and the phase shift angle in the phase shift circuit 1720 is set to 119.5 degrees.

[0167] By setting the phase shift angle in each phase shift circuit to the above angle, the combined impedance of the first line 330a and the second line 330b becomes 12.5Ω, which is only the real part, and is the same as the impedance 12.5Ω of the input transmission path 1740, so reflection is suppressed.

[0168] Fig.11 Line 1150 and line 1160 represent Fig.17 The absolute values ​​of the RF / DC conversion efficiency and reflectivity for input power in the circuit.

[0169] exist Fig.11, line 1110 represents the RF / DC conversion efficiency when only the reflection at 3 W is suppressed, line 1120 represents the reflectivity when only the reflection at 3 W is suppressed, line 1130 represents the RF / DC conversion efficiency when the reflection at 3 W and 10 W is suppressed, line 1140 represents the reflectivity when the reflection at 3 W and 10 W is suppressed, line 1150 represents the RF / DC conversion efficiency when the reflection at 1 W, 3 W and 10 W is suppressed, and line 1160 represents the reflectivity when the reflection at 1 W, 3 W and 10 W is suppressed.

[0170] According to line 1150 , the input power range with high efficiency is expanded to 0.8 to 20W.

[0171] (Fifth Embodiment: Branching into Three or More Lines; Antenna)

[0172] So far, the method of dividing the line into two has been described, but it is also possible to form an AC circuit with three or more circuits connected in parallel, and to perform impedance matching by connecting a phase shifting circuit to the input of each circuit. In this case, the number of adjustable parameters increases, so it is possible to respond to more changes in input conditions.

[0173] Again, the transmission of the antenna at multiple frequencies is used as an example for explanation. Fig.18 An example is shown in which a plurality of lines are connected in parallel to a branch point 1820, phase shift circuits 1210a to 1210n are provided at the input of each line, and an antenna is connected.

[0174] Impedance matching requires controlling two parameters: the phase and amplitude of the reflected wave. Therefore, in order to perform impedance matching, two control parameters are required for one input condition (input power or frequency).

[0175] For example, six control parameters are required to perform impedance matching for three frequencies. In this case, six phase shifting circuits with the same characteristic impedance can be used to control six phase shifting angles, or three characteristic impedances and three phase shifting angles of three phase shifting circuits can be used. In order to use six phase shifting circuits, it is sufficient to branch the line into six at the branch point 1820, and in order to use three phase shifting circuits, it is sufficient to branch the line into three at the branch point 1820.

[0176] by Fig.19 Line 1920 shows the reflectivity when six Fig.14 The antenna used in the embodiment uses six phase shift circuits each having a characteristic impedance of 50Ω. In addition to impedance matching for 2.45 GHz, impedance matching is also performed for three frequencies (eg, 2.43 GHz, 2.44 GHz, and 2.46 GHz).

[0177] Fig.19 Line 1510 represents the reflectivity of the input signal of a single antenna. By setting the characteristic impedance of the input transmission path 330 to 8.33Ω, which is 1 / 6 of 50Ω, impedance matching is achieved at the branch point 1820. At 2.45 GHz, each antenna is matched, so the overall matching is achieved even from the power supply 1811.

[0178] However, if this is the case, no matching is achieved for frequencies other than 2.45 GHz. Therefore, the phase shift angles of the six phase shift circuits are adjusted so that the reflections at 2.43 GHz, 2.44 GHz, and 2.46 GHz are zero. The optimization function of the simulator is used to randomly change the six parameters to find the optimal solution. Although the reflections cannot be completely zero at the three frequencies, the reflections can be reduced to a sufficiently low value of -50 dB. The phase shift angles of the six phase shift circuits in this case and the input admittance of each line from the branch point 1820 are shown in Table 1. In Table 1, Yre represents the real part of the admittance, and Yim represents the imaginary part of the admittance.

[0179] [Table 1]

[0180]

[0181] (Unit: mS)

[0182] For all four frequencies, the total real part of the admittance of the parallel-connected phase shift circuit is approximately 120 mS, and the total imaginary part is approximately 0 mS. This indicates that impedance matching has been established. It can be seen that because the phase shift angle changes both the real and imaginary parts of the admittance, the three real and three imaginary parts of the admittance cannot be set independently, so perfect matching is not achieved, but impedance matching sufficient for practical use is achieved over a wide frequency range.

[0183] Next, Fig.19 Line 1930 shows the reflectivity when Fig.18 Four antennas are used, and four phase shift circuits whose characteristic impedance is also variable are used to perform impedance matching for four frequencies (for example, 2.43 GHz, 2.45 GHz, 2.47 GHz, and 2.49 GHz).

[0184] In this case, the characteristic impedance of the input transmission path 330 is set to 1 / 4 of 50Ω, that is, 12.5Ω. Here, the phase shift circuit also controls the characteristic impedance together with the phase shift angle. Impedance lines with various characteristic impedances can be produced by changing the line width of the microstrip line, etc.

[0185] In this case, the characteristic impedance of the phase shift circuit is not necessarily 50Ω, so there is reflection at the antenna entrance, and it may not match even at 2.45GHz. In other words, even for 2.45GHz, it is necessary to adjust for matching. Using the optimization function of the simulator, the characteristic impedance and phase shift angle of the four phase shift circuits were adjusted and the optimal solution was obtained. The results are as follows Fig.19 As shown in 1930, it can be seen that at four frequencies, the reflection is below -80dB, and the matching is fully achieved. The input admittance of each line from the branch point 1820 in this case is shown in Table 2. In Table 2, Yre represents the real part of the admittance, and Yim represents the imaginary part of the admittance.

[0186] [Table 2]

[0187]

[0188] (Unit: mS)

[0189] For the four frequencies, although the admittance of each line is uneven, the total real part of the admittance connected in parallel is approximately 80mS, and the total imaginary part is approximately 0mS. This means that the characteristic impedance of 12.5Ω is matched and there is no reflection.

[0190] (Sixth Embodiment: Branching into Three or More Lines; Rectenna Circuit)

[0191] The matching method divided into three or more lines can also be applied to the rectenna circuit. Fig. 20 The example shown is that a plurality of rectifier circuits 820a to 820n are connected in parallel at a branch point 2020, and phase shift circuits 1210a to 1210n are provided at the input of each rectifier circuit.

[0192] Fig. 20 The rectifier circuit 820a~820n of the circuit is Figure 8 The same as 820, no matching circuit or LPF is connected. Although it can also be set as a rectifying antenna circuit connected to a matching circuit or LPF, through the optimization of multiple lines, it can have the functions of a matching circuit and an LPF, so the matching circuit or LPF part can be omitted, thereby reducing components and reducing the circuit scale.

[0193] The phase shift angle in the phase shift circuit is determined using the optimization function of the circuit simulator. The optimization function of the circuit simulator may not always make the reflectivity strictly zero, but it can make the reflectivity below the necessary conditions. On the one hand, the power value of the target for reflection suppression is specified not as a point but as a range, so the more the number of branches increases, the more uniformly the reflectivity can be reduced. On the other hand, if the number of branches increases, the number of components increases, so the two are weighed and the number of branches is determined according to the usage conditions.

[0194] Table 3 shows the optimal power ranges when two lines, four lines, and eight lines are connected, and the phase shift angle of the phase shift circuit connected to the input of each line.

[0195] [Table 3]

[0196]

[0197] Fig.21 Line 2110 shows the RF / DC conversion efficiency when the line is branched into two lines, and line 2120 shows the reflectivity. Here, optimization is performed to make the reflection at 3W zero. If the phase shift angles in each phase shift circuit when the line is branched into two lines are set to 41.3 degrees and 87.3 degrees, the reflection at 3W is suppressed, and even without a matching circuit and LPF, the same performance as that using an LPF and a matching circuit can be obtained. Fig.10 The 1110 case has roughly the same efficiency.

[0198] Fig.21 Line 2130 shows the RF / DC conversion efficiency when the line is branched into four lines, and line 2140 shows the reflectivity. Here, optimization is performed to make the reflection in the range of 0.8 to 6 W zero. The phase shift angles in each phase shift circuit are 15.0 degrees, 37.8 degrees, 56.7 degrees, and 85.4 degrees.

[0199] Fig.21 Line 2150 shows the RF / DC conversion efficiency when the branch is eight lines, and line 2160 shows the reflectivity. Here, the optimization is performed to make the reflectivity zero at 0.2 to 12 W. When the branch is eight lines, the phase shift angles in each phase shift circuit are 0.0 degrees, 15.8 degrees, 29.5 degrees, 39.4 degrees, 53.2 degrees, 64.3 degrees, 77.6 degrees, and 89.7 degrees.

[0200] In a rectifying antenna circuit, the reflectivity changes according to the power of the input signal, so the power received in each line is not uniform, and the ratio of power distributed to each line also changes according to the power of the input signal. Therefore, it is difficult to calculate the admittance of each line as is done for an antenna.

[0201] However, the combined value of the admittance can be obtained. Fig. 22 It represents the average admittance of each line. Fig. 22 The dotted line in FIG. 1 is a diagram showing the admittance using complex notation when the power of the input signal of each line is changed within a range of 0.1 to 50 W.

[0202] exist Fig.21 In the figure, the white circles, diamonds, triangles, and squares indicate the cases where the reflectance is 2% or less. Fig. 22Line 2210 shows the synthetic admittance in the case of one line using a matching circuit, line 2220 shows the synthetic admittance in the case of two lines in the present invention without connecting a matching circuit, and line 2230 shows the synthetic admittance in the case of four lines in the present invention. In the case of eight lines, since the reflectivity is mostly below 2% in this power range, it is blocked by the marks of other lines and is not shown.

[0203] In either case, the average admittance of each line is approximately 20mS in real part and zero in imaginary part. C , the real part of the resultant admittance from the branch point is exactly 1 / Z C , and the imaginary part is not exactly 0, and the reflectivity is low enough that it will not be a problem in most practical applications.

[0204] In order to suppress reflection, two parameters need to be adjusted for one input condition. Therefore, although more accurate adjustment can be made by increasing the number of lines, the cost will increase. Therefore, the number of divisions is determined based on the balance between the strictness of the conditions within the control range and the cost increase caused by the number of divisions.

[0205] (Seventh Embodiment: Phase Shift Circuit in Low Frequency Region)

[0206] In the second to sixth embodiments, the input signal is a microwave with a frequency of 2.45 GHz or 5.8 GHz. In addition to the LPF and matching circuit, an impedance line is used as a phase shift circuit. When the frequency of the input signal is low, an LC circuit is used as the phase shift circuit.

[0207] Fig.23 23 is a diagram showing a rectifying antenna circuit that uses a phase shift circuit composed of an LC circuit for an input signal of 13.56 MHz. The diode is a commercially available silicon Schottky barrier diode. Power supply 2311 is connected to one end of capacitor 2322. The other end of capacitor 2322 is connected to one end of inductor 2326a. The other end of inductor 2326a is connected to one end of inductor 2326b, the cathode of SBD2323, and the anode of SBD2324. The other end of inductor 2326b is connected to one end of capacitor 2326c. The other end of capacitor 2326c is grounded.

[0208] The anode of SBD2323 is grounded, and the cathode of SBD2324 is connected to the load 130 .

[0209] The inductor 2326a, the inductor 2326b, and the capacitor 2326c constitute an LPF and a matching circuit 2326. The SBD 2323, the SBD 2324, and the capacitor 2325 constitute a rectifier circuit 2320. The rectifier circuit 2320, the LPF, and the matching circuit 2326 constitute a rectifying antenna circuit 2340.

[0210] Here, if the load 130 is a constant voltage load of 100V, the inductance of the inductor 2326a is 828nH, the inductance of the inductor 2326b is 177nH, and the capacitance of the capacitor 2326c is 86.6pF, then the rectifying antenna circuit 2340 is matched to the input power of 10W and no reflection occurs.

[0211] Fig.24 It means two Fig.23 A diagram of a circuit connected in parallel.

[0212] The input transmission path 330 connected to the power source 2311 is branched into a first line 2430 and a second line 2440 through the branch point 320 .

[0213] The first line 2430 has a phase shift circuit 2410, and the second line 2440 has a phase shift circuit 2420. These phase shift circuits are used to match the input power of 10W in a single line and the input power of 30W. The output power of the power supply 2311 is twice the power input to each line. According to the simulation using the transmission line, in order to match the input power of 30W, the phase shift angle of the phase shift circuit 2410 is set to 97.7 degrees, and the phase shift angle of the phase shift circuit 2420 is set to 155.1 degrees. Therefore, the inductance of the inductor 2410a is set to 582nH, the capacitance of the capacitor 2410b and the capacitor 2410c is set to 269pF, the inductance of the inductor 2420a is set to 247nH, and the capacitance of the capacitor 2420b and the capacitor 2420c is set to 1063pF. In this way, the phase shift circuits 2410 and 2420 can achieve their respective desired phase shift angles when the input and output impedances are 50Ω.

[0214] Fig.25 It is for Fig.23 The circuit and Fig.24 A graph showing the RF / DC conversion efficiency and reflectivity of a circuit when input power varies.

[0215] Line 2510 indicates Fig.23 The RF / DC conversion efficiency of the single line circuit is shown in line 2520. Fig.23 Line 2530 represents the reflectivity of a single line circuit. Fig.24 The RF / DC conversion efficiency of the circuit is shown in line 2540. Fig.24 The reflectivity of the circuit.

[0216] according to Fig.25 It can be seen that: Fig.23 Compared with the single line circuit, Fig.24 The multiple line circuit maintains high efficiency over a wider range of input power.

[0217] Although circuits with the same characteristics are used as rectifier circuits (AC circuits) connected to the lines in the second to seventh embodiments, they do not necessarily need to be the same circuits. Even if they are circuits with different characteristics, reflection can be suppressed by setting the phase shift amount of each line to a phase shift amount that makes the absolute value of the imaginary part of the impedance of each line the same but opposite in sign and the real part of the combined impedance equal to the real part of the impedance before branching. This has been shown in the first embodiment.

[0218] [Effect]

[0219] As described above, according to the present disclosure, by setting a phase shift circuit in each line after branching into multiple lines, it is possible to prevent the reflection of high-frequency signals in AC equipment for multiple different input signals. The antenna can radiate radio waves of different frequencies and can radiate radio waves in a wider band. The input impedance of the rectenna changes according to the input power, so according to the present disclosure, it is possible to prevent reflection for a wide range of input powers, thereby achieving high efficiency. In addition, it can also be combined with an existing matching circuit, in which case, reflection can be suppressed over a larger range.

[0220] The phase shift circuit can be an impedance line or an LC circuit. In addition, the input signal frequency can also be handled in a wide frequency range from kHz to GHz.

[0221] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-mentioned specific embodiments, and various modifications and changes can be made within the scope of the spirit of the present disclosure described in the claims.

[0222] The disclosure contents of the specification, drawings and abstract contained in Japanese patent application No. 2023-181151 filed on October 20, 2023 are incorporated herein by reference in their entirety.

[0223] Industrial Applicability

[0224] By applying the present disclosure to a rectifying antenna circuit, even when input power varies greatly during contactless power supply, high conversion efficiency can be achieved, thereby preventing waste of power.

Claims

1. An AC device, characterized in that: include: The output impedance is Z C A transmission line, one end of which is connected to an AC power source; a plurality of phase shifting circuits connected to the other end of the transmission line; as well as The AC circuit connected to each phase shifting circuit, Each phase shift circuit has a plurality of conditions for the input signal so that the real part of the synthetic admittance seen from the other end point is 1 / Z C The phase shift angle and characteristic impedance with zero imaginary part.

2. The AC device according to claim 1, wherein: The AC circuits connected to the phase shifting circuits are all antennas.

3. The AC device according to claim 1, wherein: The AC circuits connected to the phase-shifting circuits are all rectifier circuits.

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