A terahertz frequency doubler with parallel multi-variable anodes

Abstract

The present invention belongs to the technical field of terahertz devices, specifically a terahertz frequency doubler with parallel multi-variable anodes. The present invention adopts the form of multiple rows of parallel connection for the single-row diodes in the conventional frequency doubler, and then copies the single-row diode pairs and moves them up and down along the wide side of the substrate for parallel connection; the energy not fully absorbed and utilized by the single-row diode pairs is recovered by the other rows of diode pairs, and the correlation between the increase in the number of overall tube cores and the width of the substrate is greatly reduced, thereby improving the signal utilization conversion rate; and the distance from each row of diodes to the short-circuit surface is different, and the effect on low-frequency and high-frequency signals is different. Then, by adjusting the anode diameter of each row of diodes and the spacing between the diodes, the low-frequency and high-frequency output efficiency is maximized, thereby maximizing the overall output and achieving overall flat and efficient output across the entire frequency band. The present invention solves the problem that the output efficiency of existing terahertz frequency doublers decreases as the number of diodes increases.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz devices and relates to a high-power single-input and single-output terahertz frequency doubler, in particular to a terahertz frequency doubler with parallel multi-variable anodes. Background Art

[0002] Electromagnetic waves with a frequency range of 0.1-10THz are usually defined as terahertz waves (THz waves). They are between millimeter waves and infrared light, and are in the transition zone from electronics to optics. Terahertz technology has significant advantages over traditional technologies in terms of penetration, safety, spectral resolution characteristics, and high-speed transmission. These advantages make terahertz technology have broad application prospects in many fields such as communications, medical treatment, security inspection, and radar. Stable terahertz sources are extremely important in the field of terahertz communications. At present, solid-state frequency doubling sources based on semiconductor technology that have developed from the microwave frequency band to the terahertz frequency band occupy the main position of terahertz sources, with obvious advantages such as high reliability, low cost, small size and easy integration.

[0003] Traditional terahertz solid-state frequency multipliers utilize rectangular waveguides for input. The input signal is fed into diodes arranged in a row. After generating the second harmonic, it is transferred to the output probe through a multi-section microstrip matching circuit and then output through a standard rectangular waveguide. In this structure, the substrate width increases with the number of diodes, which leads to increased signal transmission loss. Furthermore, as the number of anodes increases, the frequency multiplication efficiency of each diode decreases, resulting in a decrease in the overall output of the frequency multiplier. Summary of the Invention

[0004] In response to the above-mentioned problems or shortcomings, and to address the problem that the output efficiency of existing terahertz frequency multipliers decreases as the number of diodes increases, the present invention provides a terahertz frequency doubler with parallel multi-variable anodes. The frequency doubler is input to the diodes by multi-stage waveguide matching. The diodes are in the form of multiple rows in parallel, which increases the number of tube cores while keeping the substrate width unchanged, thereby improving the power capacity of the device. That is, the substrate width is shortened while increasing the number of tube cores, thereby reducing the parasitic resistance of the diodes. Energy not fully absorbed and utilized by a single row of diodes is recovered by other rows of diodes, thereby improving energy utilization. The distance from each row of diodes to the short-circuit board is different, and the effect on low-frequency and high-frequency signals is different. By adjusting the number of parallel diodes and the anode diameter of each row of diodes, the low-frequency and high-frequency output efficiency is maximized, thereby maximizing the overall output and achieving overall flat and efficient output across the entire frequency band.

[0005] A terahertz frequency doubler with parallel variable anodes comprises an input matching waveguide, an input / output matching microstrip, a parallel diode pair, an output microstrip probe, an output matching waveguide and a CMRC filter.

[0006] The input matching waveguide has a first section that is a standard WR-12 waveguide, several other sections that are branch matching waveguides, and a final stage that is a short-circuit surface. By continuously reducing the waveguide height, the width of the final stage reduced waveguide is made consistent with the width of the substrate and matched with the diode parameters, thereby achieving uniform feeding of terahertz energy into the parallel diode pair.

[0007] The input / output matching microstrip enables the input electromagnetic wave to be better coupled to the diode to generate the second harmonic, and the output matching microstrip transmits the second harmonic generated by the diode to the output matching waveguide end and reflects other useless harmonics.

[0008] The parallel diode pairs are formed by replicating a single row of diode pairs and then shifting them up and down along the wide side of the substrate before being connected in parallel. After the shift, the length and width of the microstrips between diodes on different sides of the same row and the length and width of the microstrips between diode pairs in different rows are adjusted. At the same time, the anode diameters of diodes in different rows are adjusted to achieve the best output effect.

[0009] Furthermore, to increase output power, the number of diodes needs to be increased. Using a traditional linear structure with diodes placed in a straight line results in increased substrate width and decreased efficiency. Connecting multiple rows of diodes in parallel solves this problem, reducing the substrate width while using a larger number of diodes, thereby increasing the power capacity and output power of the frequency multiplier.

[0010] The output microstrip probe converts the second harmonic generated by the parallel diode pair into a quasi-TEM mode in the output matching microstrip and outputs it from the output matching waveguide.

[0011] The output matching waveguide is a multi-section height-reducing waveguide that eventually transitions to a standard WR-6 waveguide output; the last stage of the output matching (height-reducing) waveguide is a short-circuit board.

[0012] The main purpose of the CMRC filter is to perform DC feeding while preventing the generated second harmonic energy from leaking through the DC terminal, so that the energy passes through the output microstrip probe and then to the output matching waveguide for output.

[0013] Furthermore, the parallel diode pairs can achieve maximum output efficiency across all frequency bands by adjusting the distance between each column of diode pairs and the short-circuit board.

[0014] Furthermore, when the number of parallel diode pairs exceeds two, the total length of a single row of diode pairs (adjusting the spacing between diodes in a single row) across the width of the substrate is gradient. By introducing a gradient linear structure, reflections and losses caused by step discontinuities are reduced. The gradient microstrip line also provides more matching levels, making field transmission more natural and efficient.

[0015] In summary, the present invention cleverly connects multiple rows of linear doubler structures in parallel, thereby increasing the number of diodes while controlling the substrate width. The anode diameters of diodes in different columns are adjusted to achieve the best output effect, thus achieving higher output and higher efficiency across the entire frequency band. This structure may be of great significance to future terahertz communication devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an overall structural diagram of an embodiment device;

[0017] Figure 2 A detailed diagram of a double row of parallel diode pairs in an embodiment device;

[0018] Figure 3 is an input efficiency curve diagram of the embodiment device;

[0019] Figure 4 Graph showing the output power and efficiency of the device in the embodiment. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] In this embodiment, terahertz fundamental waves are input into a standard rectangular waveguide using HFSS simulation software. Input matching is performed by optimizing the length and width of the waveguide at each level, as well as the distance from the end short-circuit surface to the diode, so that energy can be better fed into the parallel diode pair. In this embodiment, the parallel diode pair is connected in double rows in parallel to achieve efficient energy utilization.

[0022] like Figure 1 As shown in the figure, the overall structure of the device of this embodiment is shown. The energy is fed into the double-row parallel diode pair through the input matching waveguide. The details of the double-row parallel diode pair are shown in Figure 2 As shown, a single row of six diodes is used, for a total of 12 Schottky diodes. The two parallel rows of diode pairs have a larger anode diameter in one row and a smaller anode diameter in the other, achieving efficient utilization of both low- and high-frequency input signals. This is then achieved through a microstrip circuit and an output matching transition to achieve optimal second harmonic output.

[0023] For the frequency multiplier, the nonlinear effect of the current and voltage across the diode is used to achieve the frequency multiplication of the input signal. The nonlinear IV characteristic curve is expanded into a Taylor series at a fixed bias point V, and the output current i o for

[0024] i o =f(V+v)=a0+a1v+a2v 2 +a3v 3 +...+an v n

[0025] Among them, a0 represents the DC component of the output; a1 represents the fundamental component of the output; a n Represents the nth harmonic component.

[0026] For the frequency multiplier, the input is generally a single-tone signal. Assume that the input signal is a sinusoidal signal v in =V0 cosω0t, where V0 represents the signal amplitude, ω0 represents the signal frequency, and t represents time. Output current i out for:

[0027]

[0028] As can be seen from the above formula, due to the nonlinear effect of the diode, a large number of harmonic components will be generated after a sinusoidal signal is input. The power of each component is different. Through multi-section microstrip matched filtering with different impedances, the required second harmonic signal is selected and the output is extracted as much as possible to obtain the double frequency of the input signal.

[0029] The frequency doubler is input to the diodes by multi-stage waveguide matching. The diodes are in the form of multiple rows in parallel. The increase in the number of tube cores improves the power capacity of the device, shortens the substrate width, and reduces the parasitic resistance of the diodes. The energy not fully absorbed and utilized by one row of diodes is recovered by other rows of diodes, and the efficiency remains unchanged while the number of tube cores increases. The distance from each row of diodes to the short-circuit board is different, and the effect on low-frequency and high-frequency signals is different. The anode diameter of each row of diodes is adjusted to maximize the low-frequency and high-frequency output efficiency, thereby maximizing the overall output and achieving overall flat and efficient output across the entire frequency band.

[0030] like Figure 3 As shown in FIG, this figure is an input efficiency diagram of the device of this embodiment. The structure has good input matching, and the energy of the terahertz fundamental wave can be utilized by the diode as much as possible to generate the second harmonic.

[0031] like Figure 4 As shown in the figure, this figure is the output power and efficiency diagram of the device of this embodiment. It can be found that the structure has high power output in the entire frequency band, and the output efficiency is mostly above 8%, achieving a high conversion efficiency while achieving a large working bandwidth.

[0032] As can be seen from the above embodiments, the present invention adopts the form of multiple rows of parallel connection of single-row diodes in conventional frequency multipliers, and then replicates the single-row diode pairs and moves them up and down along the wide side of the substrate for parallel connection; the energy not fully absorbed and utilized by the single-row diode pairs is recovered by other rows of diode pairs, and the correlation between the increase in the number of overall tube cores and the width of the substrate is greatly reduced, thereby improving the utilization conversion rate of the signal; and each row of diode pairs has a different distance to the short-circuit surface, and has different effects on low-frequency and high-frequency signals. Then, by adjusting the anode diameter of each row of diodes and the spacing between the diodes, the low-frequency and high-frequency output efficiency is maximized, thereby maximizing the overall output and achieving overall flat and efficient output across the entire frequency band. The present invention solves the problem that the output efficiency of existing terahertz frequency multipliers decreases as the number of diodes increases, and is of great significance to future terahertz communication devices.

Claims

1. A terahertz frequency doubler with a parallel multi-variable anode, characterized by: Includes input matching waveguide, input / output matching microstrip, parallel diode pair, output microstrip probe, output matching waveguide and CMRC filter; The input matching waveguide has a standard WR-12 waveguide in the first section, branch matching waveguides in the other sections, and a short-circuit surface at the final stage. By continuously reducing the height of the waveguide, the width of the final stage reduced waveguide is made consistent with the width of the substrate and matched with the diode parameters, so that the terahertz energy is evenly fed into the parallel diode pair. The input / output matching microstrip couples the input electromagnetic wave to the parallel diode pair to generate the second harmonic, and the output matching microstrip transmits the second harmonic generated by the parallel diode pair to the output matching waveguide end and reflects other useless harmonics; The parallel diode pairs are constructed by replicating a single row of diode pairs and then shifting them up and down along the wide side of the substrate before connecting them in parallel. After the shifting, the length and width of the microstrips between diodes on different sides of the same row and between diode pairs in different rows are adjusted. At the same time, the anode diameters of the diodes in different rows are adjusted, with one row of diodes having a larger anode diameter and another row having a smaller anode diameter, so that the output efficiency of each row of diode pairs in the corresponding frequency band is maximized. The output microstrip probe converts the second harmonic generated by the parallel diode pair into a quasi-TEM mode in the output matching microstrip and outputs it from the output matching waveguide; The output matching waveguide is a multi-section height-reducing waveguide that eventually transitions to a standard WR-6 waveguide output, with the final stage being a short-circuit waveguide. The CMRC filter performs DC feeding and simultaneously prevents the generated second harmonic energy from leaking through the DC terminal, so that the energy passes through the output microstrip probe and then outputs to the output matching waveguide.

2. The terahertz frequency doubler with parallel multi-variable anodes as claimed in claim 1, characterized in that: The parallel diode pairs increase the number of parallel-connected single-row diodes without changing the width of the substrate, thereby increasing the number of overall dies and improving the power capacity of the overall device.

3. The terahertz frequency doubler with parallel multi-variable anodes as claimed in claim 1, characterized in that: The parallel diode pairs can achieve maximum output efficiency across all frequency bands by adjusting the distance between each column of diode pairs and the short-circuit board.

4. The terahertz frequency doubler with parallel multi-variable anodes as claimed in claim 1, characterized in that: The number of parallel diode pairs connected in parallel is equal to 2.

5. The terahertz frequency doubler with parallel multi-variable anodes as claimed in claim 1, characterized in that: When the number of parallel diode pairs is greater than 2, the total length of a single row of diode pairs in the width direction of the substrate changes gradually.

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