Extensible silicon-based terahertz radiation array source based on on-chip micro-convex antenna and terahertz radiation source

Abstract

The invention discloses an extensible silicon-based terahertz radiation array source based on an on-chip micro-convex antenna and a terahertz radiation source. The extensible silicon-based terahertz radiation array source based on the on-chip micro-convex antenna comprises a plurality of array units formed by cross-coupled harmonic oscillators based on the on-chip micro-convex antenna, and the array units are connected to form the extensible silicon-based terahertz radiation array source of an n * n array structure. According to the extensible silicon-based terahertz radiation array source, the on-chip micro-convex antenna radiation structure meets the terahertz frequency and broadband requirements, the extensible silicon-based terahertz radiation array source can be applied to a terahertz radiation source system, and the terahertz radiation source array system which is high in working frequency, high in radiation power and tunable in broadband can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz radiation array sources, and in particular to an expandable silicon-based terahertz radiation array source and a terahertz radiation source based on an on-chip micro-convex antenna. Background Art

[0002] Terahertz radiation sources have great potential in a variety of applications such as high-speed communications, imaging, high-resolution radar and non-destructive testing. Silicon-based processes have become a research hotspot for future terahertz radiation sources due to their high integration, low cost and miniaturization. Due to the characteristics of silicon materials, frequency limitation has become one of the main challenges facing silicon-based terahertz sources.

[0003] In the disclosed technology, the design is higher than the transistor f max The silicon-based terahertz source mainly includes the following two schemes. One is to use a frequency multiplier or a frequency multiplication chain for the millimeter wave frequency source; the other is to use a harmonic oscillator, through impedance matching optimization design, to extract harmonics in the output and suppress other harmonics. Compared with the frequency multiplication scheme, the harmonic oscillator has higher efficiency and lower power consumption. However, for the use of the harmonic method to generate terahertz signals, the following two situations still need to be considered. One is to design an oscillator with a low fundamental frequency, but it is necessary to extract higher harmonics, resulting in a rapid decrease in output power; the other is to reduce the harmonic order of the harmonic oscillator, but it is necessary to design a high fundamental frequency oscillator, close to f max The oscillator core design is difficult. In summary, the selection of silicon-based terahertz source system architecture requires a trade-off between frequency, output power, power consumption and design difficulty.

[0004] In addition, silicon-based terahertz sources also face the challenge of power radiation. The transmission distance of terahertz waves is relatively short compared to millimeter waves, and considering the non-contact and high-resolution diversified applications of terahertz in special fields such as communications, radar, imaging, and non-destructive testing, terahertz sources output power in the form of radiation. The terahertz source radiation technology that has been disclosed mainly includes the following two solutions: one is to use an on-chip antenna to radiate power from the front of the chip. Since the on-chip antenna has low radiation efficiency and most of the transmission power is radiated in the silicon substrate, a metal reflector is usually attached to the back of the chip to increase the radiation power; the other is to use an on-chip antenna but attach a high-resistivity super-hemispherical silicon lens to the back of the chip to radiate power from the back of the chip and refocus the power lost in the substrate, which can significantly improve the radiation efficiency and directivity, but requires a more complex packaging process, and the silicon lens is expensive, which will offset the cost-effectiveness of using silicon-based processes.

[0005] In addition, the radiation power of a single radiation source is limited, so the existing terahertz radiation sources tend to develop in the form of arrays. Terahertz radiation array sources can combine multiple radiation units to emit, thereby enhancing the radiation power of the entire system, improving the radiation directivity, and achieving beamforming, thereby improving system performance and application flexibility. Summary of the invention

[0006] The purpose of the present invention is to overcome one or more problems of current silicon-based terahertz radiation sources, such as low operating frequency, low output power, low radiation efficiency and inability to perform broadband frequency tuning, and to provide an expandable silicon-based terahertz radiation array source and terahertz radiation source based on on-chip micro-convex antennas. The terahertz radiation array source and terahertz radiation source are high operating frequency, high radiation power and broadband tunable expandable silicon-based terahertz radiation source.

[0007] A first aspect of the present invention provides an expandable silicon-based terahertz radiation array source based on on-chip micro-convex antennas, including an expandable silicon-based terahertz radiation array source based on on-chip micro-convex antennas, characterized in that it includes multiple array units composed of cross-coupled harmonic oscillators based on on-chip micro-convex antennas, and multiple of the array units are connected to form an expandable silicon-based terahertz radiation array source with an n×n array structure.

[0008] Each of the array units is composed of a pair of cross-coupling pairs, two source inductors, two drain inductors and an on-chip micro-convex antenna, and the cross-coupling pair is composed of a pair of cross-coupled transistors, and the source inductor and drain inductor of each transistor are coupled with a predetermined coupling coefficient.

[0009] Among them, the source of each transistor is connected to one end of a source inductor, the drain of each transistor is connected to one end of a drain inductor, the other ends of the two source inductors are grounded, and the other ends of the two drain inductors are connected to the differential feed end of the on-chip micro-convex antenna. The on-chip micro-convex antenna radiates a high-power Nth harmonic signal, that is, a radiation signal with a frequency of Nf0.

[0010] The on-chip micro-convex antenna radiates a high-power Nth harmonic signal, where N represents the order of extracted harmonics, which is determined by the impedance parameters of the output matching network formed by the on-chip micro-convex antenna.

[0011] Among them, multiple array units are interconnected and expanded between the gates of the cross-coupled pairs of adjacent harmonic oscillators through transmission lines, and the core circuit of each unit is locked at the fundamental frequency f0 to form an expandable silicon-based terahertz radiation array source with an n×n array structure.

[0012] The second aspect of the present invention provides another scalable silicon-based terahertz radiation source based on an on-chip micro-convex antenna, which is a quad-core coupled oscillator with a dual injection locking structure based on an on-chip micro-convex antenna, including an on-chip micro-convex antenna and four cross-coupling pairs, each cross-coupling pair including two transistors, the source of each transistor is connected to one end of a source inductor, the drain of each transistor is connected to one end of a drain inductor, the gate of each transistor is connected to one end of a gate inductor, the other end of the two source inductors of each cross-coupling pair is grounded, and the other end of the two drain inductors is connected to the differential feed end of the on-chip micro-convex antenna;

[0013] The drain inductance of each cross-coupling pair is coupled with the source inductance of an adjacent cross-coupling pair at a first coupling coefficient, and the gate inductances between adjacent cross-coupling pairs are coupled at a second coupling coefficient. Mutual injection locking between the cross-coupling pairs is achieved through the two coupling structures, thereby enhancing the locking between the core circuits of the cross-coupling pairs at the fundamental frequency f0.

[0014] Among them, in each cross-coupling pair, the drain terminals of the two transistors generate a differential Nth harmonic signal, and the adjacent cross-coupling pairs are connected according to the phase to form four-way connected Nth harmonic signals with a phase of 0° and four-way connected Nth harmonic signals with a phase of 180°, and then a pair of differential signals synthesized by the four-way connected Nth harmonic signals with a phase of 0° / 180° are used to drive the on-chip micro-convex antenna of the differential structure, and the on-chip micro-convex antenna radiates high-power Nth harmonics, that is, the radiation signal with a frequency of Nf0.

[0015] Among them, the structures of the four cross-coupling pairs are the same, and the on-chip micro-convex antenna radiates high-power Nth harmonic signals, where N represents the extracted harmonic order, which is determined by the impedance parameters of the output matching network formed by the on-chip micro-convex antenna.

[0016] The power of the Nth harmonic signal is maximized by optimizing the first coupling coefficient and the second coupling coefficient.

[0017] The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antenna proposed in the present invention has an on-chip micro-convex antenna radiation structure that meets the terahertz frequency and broadband requirements, can be applied to a terahertz radiation source system, and can realize a high operating frequency, high radiation power, and broadband tunable terahertz radiation source array system.

[0018] The scalable silicon-based terahertz radiation source array based on on-chip micro-convex antennas proposed in the present invention has the characteristics of low cost, high integration, and miniaturization, and can be flexibly expanded according to the requirements of application scenarios to generate radiation power of different intensities.

[0019] The quad-core coupled oscillator with a dual injection locking structure based on an on-chip micro-convex antenna proposed in the present invention utilizes a dual injection locking structure to achieve locking between cores at the fundamental frequency f0, and can also provide additional voltage clearance for the drain output by coupling the drain inductance of a unit with an adjacent inductor through a cross-coupling pair, thereby effectively increasing the maximum amplitude of the oscillator oscillation and improving efficiency.

[0020] The quad-core coupled oscillator with a dual injection locking structure based on an on-chip micro-convex antenna proposed in the present invention can also be expanded as an array unit in an array expansion manner and applied to a terahertz radiation source system. By expanding the array, a high operating frequency, high radiation power, and broadband tunable terahertz radiation source array system can be realized. At the same time, it has the characteristics of low cost, high integration, and miniaturization, and can be flexibly expanded according to the requirements of application scenarios to generate radiation powers of different intensities. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a circuit diagram of a cross-coupled harmonic oscillator based on an on-chip micro-convex antenna of the present invention.

[0022] Figure 2 This is a circuit diagram of the expandable silicon-based terahertz radiation array source of the 2×2 array structure of the present invention.

[0023] Figure 3 This is a circuit diagram of the expandable silicon-based terahertz radiation array source of the 3×3 array structure of the present invention.

[0024] Figure 4 This is a circuit diagram of an expandable silicon-based terahertz radiation array source with an n×n array structure of the present invention.

[0025] Figure 5 This is a circuit diagram of the scalable silicon-based terahertz radiation source based on the on-chip micro-convex antenna of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Starting from the bottom of the cutoff frequency of the silicon-based process, the present invention designs an oscillator unit that is different from the traditional architecture to achieve high-frequency and high-power output. It uses an on-chip micro-convex antenna as a broadband radiation structure with high radiation efficiency, high radiation intensity, and directional radiation to maximize energy radiation.

[0028] The present invention fully utilizes the advantages of silicon technology and adopts an expandable array layout to ultimately achieve a high-frequency, wide-spectrum and high-energy-efficiency silicon-based terahertz radiation array source.

[0029] like Figures 1 to 4As shown, the scalable silicon-based terahertz radiation array source based on on-chip micro-convex antennas of an embodiment of the present invention is an array unit composed of a cross-coupled transistor with drain inductance and source inductance coupled, and an on-chip micro-convex antenna as an oscillator. The gates of adjacent array units are interconnected through transmission lines to form an array structure, including a scalable silicon-based terahertz radiation array source based on on-chip micro-convex antennas, including multiple array units composed of cross-coupled harmonic oscillators based on on-chip micro-convex antennas, and multiple array units are connected to form an scalable silicon-based terahertz radiation array source with an n×n array structure.

[0030] Each of the array units is composed of a pair of cross-coupling pairs, two source inductors, two drain inductors and an on-chip micro-convex antenna, and the cross-coupling pair is composed of a pair of transistors, and the source inductor and drain inductor of each transistor are coupled with a predetermined coupling coefficient.

[0031] In this application, the cross-coupling pair described herein is referred to as Figure 1 As shown, M1 and M2 are two transistors in a cross-coupled pair, which provide sufficient negative resistance for the oscillator structure to maintain oscillation and generate differential oscillation signals at their drains; A1 is an on-chip micro-convex antenna, and the drains of the two transistors M1 and M2 are respectively connected to the differential feed ends of the on-chip micro-convex antenna A1. In the present application, the on-chip micro-convex antenna A1 with a differential structure has two functions: on the one hand, it provides the best load impedance to facilitate the extraction of Nth harmonics, and on the other hand, it radiates the signal.

[0032] The gate of transistor M1 is coupled to the drain of M2, and the gate of transistor M2 is coupled to the drain of M1, thereby forming a cross-coupled pair. Figure 2 , 3 as well as Figure 4 The structure of the cross-coupling pairs in Figure 1 same.

[0033] The source of each transistor is connected to a source inductor L s The drain of each transistor is connected to a drain inductor L d One end, the other end of the two source inductors is grounded, and the other end of the two drain inductors is connected to the differential feeding end of the on-chip micro-convex antenna. The source inductor and the drain inductor are coupled with a coupling coefficient k1.

[0034] For details, see Figure 4 As shown, transistor M 11 With transistor M 12 , transistor M 21 With transistor M 22 ,......, transistor M n1 With transistor M n2are the cross-coupled transistors of the 1st, 2nd, ..., nth array units, L d1 , L d2 ,......,L dn is the leakage inductance of each unit, L s1 , L s2 ,......,L sn is the source inductance of each unit, L of each array unit dn and L gn The coupling coefficient k n Coupling, where k1 = k2 = ... = k n Since the waveforms of the drain and source are in phase, the voltage swing of the drain will be enhanced accordingly through transformer coupling. This phase synchronization provides additional voltage headroom for the drain voltage of the oscillator, enhances the driving capability of the oscillator of this structure, and effectively increases the maximum amplitude of the oscillator.

[0035] Among them, multiple array units are interconnected and extended through transmission lines to the gates of the cross-coupled pairs of adjacent harmonic oscillators, and the core circuit of each unit is locked at the fundamental frequency f0 to form an expandable silicon-based terahertz radiation array source with an n×n array structure, see Figure 2 , Figure 3 as well as Figure 4 shown.

[0036] in, Figure 2 , Figure 3 , Figure 4 The circuit diagrams of the scalable silicon-based terahertz radiation array sources with 2×2 array structure, 3×3 array structure and n×n array structure respectively include 4 array units, 9 array units, n 2 array units; each array unit includes an on-chip micro-convex antenna A n ,n=1,2,......,n. The on-chip micro-convex antenna is connected to the power supply V DD .

[0037] The circuit design of the scalable silicon-based terahertz radiation array source based on the on-chip micro-convex antenna described above includes the following steps:

[0038] (1) Determine the operating frequency, radiation power, frequency modulation range, power consumption and other index requirements of the silicon-based terahertz source, conduct active device modeling based on the adopted process, introduce passive embedded structures to improve the transistor structure and control its interconnection layout, and improve the circuit f max and DC-THz conversion efficiency.

[0039] (2) After determining the transistor size, debug the single array unit. According to the actual requirements of the extracted harmonic order, use the on-chip micro-convex antenna as a load for impedance matching, determine the optimal load size, achieve harmonic extraction, and have a certain harmonic suppression function. In addition, adjust the on-chip micro-convex antenna to have the best radiation efficiency and radiation directivity, and iterate the active part and passive radiation structure until the optimal radiation state is achieved.

[0040] (3) Combine multiple array units and lock the frequency between units through the transmission line TL to enhance the radiation power of the entire system. Verify different array sizes and achieve precise control of the radiation beam direction and shape by adjusting the phase and amplitude of a single radiating unit, so that the radiation beam shape and direction can be flexibly adjusted, improving system flexibility and performance.

[0041] See also Figure 5 As shown, in the second aspect of the present invention, another scalable silicon-based terahertz radiation source based on an on-chip micro-convex antenna is provided, which is a quad-core coupled oscillator with a dual injection locking structure based on an on-chip micro-convex antenna, including an on-chip micro-convex antenna and four cross-coupling pairs, each cross-coupling pair including two transistors M1 and M2, and the source of each transistor is connected to a source inductor L s The drain of each transistor is connected to a drain inductor L d The gate of each transistor is connected to a gate inductor L g one end of the two source inductors of each cross-coupling pair is connected to the ground, and the other end of the two drain inductors is connected to the differential feeding end of the on-chip micro-convex antenna;

[0042] The drain inductance of each cross-coupling pair is coupled with the source inductance of an adjacent cross-coupling pair at a first coupling coefficient, and the gate inductances between adjacent cross-coupling pairs are coupled at a second coupling coefficient. Mutual injection locking between the cross-coupling pairs is achieved through the two coupling structures, thereby enhancing the fundamental frequency locking between the cross-coupling pairs.

[0043] The cross-coupling method of the cross-coupling pair is shown in Figure 1 and related descriptions.

[0044] Specific as Figure 5 As shown, transistors M1 and M2 are cross-coupled pairs of each unit, and their source, gate, and drain are respectively connected to the source inductor L s , gate inductance L g and the drain inductance L d A1 is the on-chip micro-convex antenna, through the leakage inductor L d The drain inductance L of each cross-coupled pair is dThe first coupling coefficient k1 and the adjacent core source inductance L s coupling, and the gate inductance L between adjacent cross-coupled pairs g They are also coupled with a second coupling coefficient k2.

[0045] Among them, the drain terminals of the two transistors in each cross-coupling pair generate a differential Nth harmonic signal, and the adjacent cross-coupling pairs are connected according to the phase to form four-way connected Nth harmonic signals with a phase of 0° and four-way connected Nth harmonic signals with a phase of 180°, and then a pair of differential signals synthesized by the four-way connected Nth harmonic signals with a phase of 0° / 180° are used to drive the on-chip micro-convex antenna of the differential structure, and the on-chip micro-convex antenna radiates high-power Nth harmonics.

[0046] The size and / or shape of the micro-convex antenna can be adjusted according to the optimal impedance matching so as to generate Nth harmonics that radiate high power.

[0047] The four cross-coupling pairs have the same structure, and the power of the Nth harmonic signal is maximized by optimizing the first coupling coefficient and the second coupling coefficient.

[0048] The circuit design of the quad-core coupled oscillator based on the dual injection structure of the on-chip micro-convex antenna as described above mainly includes the following steps:

[0049] (1) Determine the operating frequency, radiation power, frequency modulation range, power consumption and other index requirements of the silicon-based terahertz source, conduct active device modeling based on the adopted process, introduce passive embedded structures to improve the transistor structure and control its interconnection layout to improve the circuit f max and DC-THz conversion efficiency.

[0050] (2) After determining the transistor size, debug the single core, use the on-chip micro-convex antenna as a load for impedance matching according to the actual need for extracting harmonic orders, determine the optimal load size, achieve harmonic extraction, and have a certain harmonic suppression function. In addition. Adjust the on-chip micro-convex antenna to have the best radiation efficiency and radiation directivity, iterate the active part and passive radiation structure until the optimal radiation state is achieved;

[0051] At the same time, a dual injection structure is added to achieve locking and maximum amplitude output between cores by adjusting the coupling inductance and coupling coefficient. In the case of quad-core coupling, the on-chip micro-convex antenna is re-adjusted to achieve the optimal load condition and maximize the radiation power.

[0052] (3) Combine and form multiple arrays with the above-mentioned quad-core coupled oscillator with dual injection structure based on on-chip micro-convex antenna as units to enhance the radiation power of the entire system. Verify different array sizes and achieve precise control of the radiation beam direction and shape by adjusting the phase and amplitude of a single radiating unit, so that the radiation beam shape and direction can be flexibly adjusted, improving system flexibility and performance.

[0053] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0054] Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that all changes falling within the meaning and range of equivalent elements of the claims are included in the present invention.

[0055] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A scalable silicon-based terahertz radiation array source based on on-chip micro-convex antennas, characterized in that: The invention comprises a plurality of array units composed of cross-coupled harmonic oscillators based on on-chip micro-convex antennas, wherein a plurality of the array units are connected to form an expandable silicon-based terahertz radiation array source with an n×n array structure.

2. The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antenna according to claim 1, characterized in that: Each of the array units is composed of a pair of cross-coupling pairs, two source inductors, two drain inductors and an on-chip micro-convex antenna. The cross-coupling pair is composed of a pair of cross-coupled transistors, and the source inductor and drain inductor of each transistor are coupled with a predetermined coupling coefficient.

3. The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antenna according to claim 2, characterized in that: The source of each transistor is connected to one end of a source inductor, the drain of each transistor is connected to one end of a drain inductor, the other ends of the two source inductors are grounded, and the other ends of the two drain inductors are connected to the differential feed end of the on-chip micro-convex antenna. The on-chip micro-convex antenna radiates a high-power Nth harmonic signal, that is, a radiation signal with a frequency of Nf0.

4. The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antenna according to claim 3, characterized in that: The on-chip micro-convex antenna radiates a high-power Nth harmonic signal, where N represents the order of extracted harmonics, which is determined by the impedance parameters of the output matching network formed by the on-chip micro-convex antenna.

5. The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antenna according to claim 3, characterized in that: The plurality of array units are interconnected and extended through transmission lines between gates of cross-coupled pairs of adjacent harmonic oscillators, and the core circuit of each array unit is locked at the fundamental frequency f0 to form an expandable silicon-based terahertz radiation array source with an n×n array structure.

6. A scalable silicon-based terahertz radiation source based on an on-chip micro-convex antenna, characterized in that: A quad-core coupled oscillator based on a dual injection structure of an on-chip micro-convex antenna includes an on-chip micro-convex antenna and four cross-coupling pairs, each cross-coupling pair includes two transistors, the source of each transistor is connected to one end of a source inductor, the drain of each transistor is connected to one end of a drain inductor, the gate of each transistor is connected to one end of a gate inductor, the other end of the two source inductors of each cross-coupling pair is grounded, and the other end of the two drain inductors is connected to the differential feeding end of the on-chip micro-convex antenna; The drain inductance of each cross-coupling pair is coupled with the source inductance of an adjacent cross-coupling pair at a first coupling coefficient, and the gate inductances between adjacent cross-coupling pairs are coupled at a second coupling coefficient. Mutual injection locking between the cross-coupling pairs is achieved through the two coupling structures, thereby enhancing the frequency locking between the core circuits of the cross-coupling pairs at the fundamental frequency.

7. The scalable silicon-based terahertz radiation source based on on-chip micro-convex antenna according to claim 6, characterized in that: In each cross-coupling pair, the drain terminals of the two transistors generate a differential Nth harmonic signal, and the adjacent cross-coupling pairs are connected according to the phase to form four-way connected Nth harmonic signals with a phase of 0° and four-way connected Nth harmonic signals with a phase of 180°. Then, a pair of differential signals synthesized from the four-way connected Nth harmonic signals with a phase of 0° / 180° are used to drive the on-chip micro-convex antenna of the differential structure, and the on-chip micro-convex antenna radiates a high-power Nth harmonic signal, that is, a radiation signal with a frequency of Nf0.

8. The scalable silicon-based terahertz radiation source based on on-chip micro-convex antenna according to claim 6, characterized in that: The four cross-coupling pairs have the same structure. The on-chip micro-convex antenna radiates a high-power Nth harmonic signal, where N represents the order of the extracted harmonics, which is determined by the impedance parameters of the output matching network formed by the on-chip micro-convex antenna.

9. The scalable silicon-based terahertz radiation source based on on-chip micro-convex antenna according to claim 6, characterized in that: The power of the Nth harmonic signal is maximized by optimizing the first coupling coefficient and the second coupling coefficient.

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