Scalable silicon-based terahertz radiation source based on micro-antenna on chip

Abstract

The application discloses a scalable silicon-based terahertz radiation array source based on a micro-protrusion antenna and a terahertz radiation source. The scalable silicon-based terahertz radiation array source based on a micro-protrusion antenna comprises a plurality of array units composed of cross-coupled harmonic oscillators based on a micro-protrusion antenna, and the plurality of array units are connected to form an n*n array structure of the scalable silicon-based terahertz radiation array source. The scalable silicon-based terahertz radiation array source has a micro-protrusion antenna radiation structure, meets the terahertz frequency and wideband requirements, can be applied to a terahertz radiation source system, and can realize a high working frequency, a high radiation power and a wideband tunable terahertz radiation source array system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of terahertz radiation array source, in particular to a scalable silicon-based terahertz radiation array source based on micro-protrusion antennas on chip and a terahertz radiation source. BACKGROUND

[0002] Terahertz radiation sources have great potential in high-speed communication, imaging, high-resolution radar and non-destructive testing and other applications. Silicon-based technology has become a research hotspot for future terahertz radiation sources due to its high integration, low cost and miniaturization. Due to the characteristics of silicon material, frequency limitation is one of the main challenges faced by silicon-based terahertz sources.

[0003] In the already disclosed technology, the design of silicon-based terahertz sources higher than the frequency limit of the transistor f max There are mainly two schemes for the design of silicon-based terahertz sources higher than the frequency limit of the transistor f max The first is to use a frequency multiplier or frequency multiplication link for a millimeter wave frequency source; the second is to use a harmonic oscillator, which is optimized by impedance matching, extracts harmonics and suppresses other harmonics in the output. Compared with the frequency multiplication scheme, the harmonic oscillator has higher efficiency and lower power consumption. However, for the generation of terahertz signals by the harmonic method, the following two cases need to be considered, one is to design an oscillator with a low fundamental frequency, but a higher harmonic needs to be extracted, resulting in a rapid decrease in output power; the other is to reduce the harmonic order of the harmonic oscillator, but a high fundamental frequency oscillator needs to be designed, which is close to the core design of the f max In summary, the selection of the silicon-based terahertz source system architecture needs to consider the 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. Compared with millimeter waves, terahertz waves have a relatively short transmission distance, and considering the non-contact, high-resolution and diversified applications of terahertz in communication, radar, imaging, non-destructive testing and other special fields, the terahertz source outputs power in the form of radiation. In the already disclosed terahertz source radiation technology, there are mainly two schemes, one is to use an on-chip antenna to radiate power from the front of the chip, because the radiation efficiency of the on-chip antenna is low, and most of the transmitted power is radiated in the silicon substrate, so a metal reflector is usually attached to the back of the chip to improve the radiation power; the second 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, 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 price of the silicon lens is expensive, which will offset the cost-effectiveness of using silicon-based technology.

[0005] In addition, the radiation power of a single radiation source is limited, and therefore existing terahertz radiation sources tend to be developed in an array form. A terahertz radiation array source can combine multiple radiation units for emission, and the radiation power of the entire system is enhanced, the radiation directivity is improved, beamforming is achieved, and the system performance and application flexibility are improved. SUMMARY

[0006] The present application aims to overcome one or more problems of the current silicon-based terahertz radiation source, such as low operating frequency, low output power, low radiation efficiency, and inability to perform wideband frequency tuning, and to provide an expandable silicon-based terahertz radiation array source based on a micro-protruding antenna on a chip and a terahertz radiation source, which is an expandable silicon-based terahertz radiation array source and a terahertz radiation source with high operating frequency, high radiation power, and wideband tunable.

[0007] In a first aspect of the present application, an expandable silicon-based terahertz radiation array source based on a micro-protruding antenna on a chip is provided, comprising an expandable silicon-based terahertz radiation array source based on a micro-protruding antenna on a chip, characterized by comprising a plurality of array units composed of cross-coupled harmonic oscillators based on a micro-protruding antenna on a chip, and the plurality of array units are connected to form an n*n array structure of the expandable silicon-based terahertz radiation array source.

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

[0009] Each transistor is connected to one end of a source inductor, each transistor is connected to one end of a drain inductor, the other end of the two source inductors is grounded, the other end of the two drain inductors is connected to the differential feed-in end of the micro-protruding antenna on a chip, and the micro-protruding antenna on a chip radiates high-power Nth harmonic signals, i.e., radiation signals with a frequency of Nf0.

[0010] The micro-protruding antenna on a chip radiates high-power Nth harmonic signals, and N represents the extraction harmonic order, which is determined by the impedance parameters of the output matching network composed of the micro-protruding antenna on a chip.

[0011] The array units are connected to each other through the transmission lines between the gates of the cross-coupled transistors of adjacent harmonic oscillators and are expanded, the core circuit of each unit is locked at the fundamental frequency f0, and an n*n array structure of the expandable silicon-based terahertz radiation array source is formed.

[0012] In a second aspect of the present application, another scalable on-chip micro-antenna based terahertz radiation source is provided, which is a four-core coupled oscillator based on a double-injection-locked structure of an on-chip micro-antenna, comprising one on-chip micro-antenna and four cross-coupled pairs, each cross-coupled pair comprising two transistors, the source of each transistor being connected to one end of a source inductor, the drain of each transistor being connected to one end of a drain inductor, the gate of each transistor being connected to one end of a gate inductor, the other end of the two source inductors of each cross-coupled pair being grounded, and the other end of the two drain inductors being connected to the differential feed-in end of the on-chip micro-antenna.

[0013] The drain inductors of each cross-coupled pair are coupled to the source inductors of the adjacent cross-coupled pair with a first coupling coefficient, and the gate inductors between the adjacent cross-coupled pairs are coupled with a second coupling coefficient, so as to realize mutual injection locking between the cross-coupled pairs through the two coupling structures and enhance the locking between the core circuits of the cross-coupled pairs at the fundamental frequency f0.

[0014] In each cross-coupled pair, the drains of the two transistors generate differential Nth harmonic signals, the adjacent cross-coupled pairs are connected in phase, forming four Nth harmonic signals connected in phase at 0° and four Nth harmonic signals connected in phase at 180°, and then a pair of differential signals synthesized by the four Nth harmonic signals connected in phase at 0° / 180° is used to drive the on-chip micro-antenna of the differential structure, and the on-chip micro-antenna radiates high-power Nth harmonic signals, i.e., radiation signals with a frequency of Nf0.

[0015] The four cross-coupled pairs have the same structure, and the on-chip micro-antenna radiates high-power Nth harmonic signals, where N represents the extraction harmonic order and is determined by the impedance parameters of the output matching network formed by the on-chip micro-antenna.

[0016] The first coupling coefficient and the second coupling coefficient are optimized to maximize the power of the Nth harmonic signals.

[0017] The on-chip micro-antenna radiation structure of the scalable on-chip micro-antenna based terahertz radiation array source meets the requirements of terahertz frequency and wideband, can be applied to a terahertz radiation source system, and can realize a terahertz radiation source array system with high operating frequency, high radiation power, and wideband tunability.

[0018] The scalable on-chip micro-antenna based terahertz radiation source array has the characteristics of low cost, high integration, and miniaturization, and can be flexibly expanded according to application scene requirements to generate different intensities of radiation power.

[0019] The four-core coupled oscillator based on the double injection locking structure of the on-chip micro-protrusion antenna provided by the application realizes locking between cores at the fundamental frequency f0 by using the double injection locking structure, and through the inductance coupling between the drain inductance of a cross-coupling pair unit and the adjacent inductance, additional voltage headroom can also be provided for the drain output, thereby effectively improving the maximum amplitude of the oscillator oscillation and improving the efficiency.

[0020] The four-core coupled oscillator based on the double injection locking structure of the on-chip micro-protrusion antenna provided by the application can also be expanded in an array expansion mode as an array unit, and is applied to a terahertz radiation source system, and through expansion of the array, a terahertz radiation source array system with high working frequency, high radiation power and wideband tunable is realized, and meanwhile, the terahertz radiation source array system has the characteristics of low cost, high integration and miniaturization, and can be flexibly expanded according to the application scene requirement to generate radiation power of different intensities. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a circuit diagram of the cross-coupling harmonic oscillator based on the on-chip micro-protrusion antenna of the application.

[0022] Figure 2 It is a circuit diagram of the expandable silicon-based terahertz radiation array source with a 2*2 array structure of the application.

[0023] Figure 3 It is a circuit diagram of the expandable silicon-based terahertz radiation array source with a 3*3 array structure of the application.

[0024] Figure 4 It is a circuit diagram of the expandable silicon-based terahertz radiation array source with an n*n array structure of the application.

[0025] Figure 5 It is a circuit diagram of the expandable silicon-based terahertz radiation source based on the on-chip micro-protrusion antenna of the application. DETAILED DESCRIPTION

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

[0027] The application designs an oscillator unit different from the traditional architecture from the perspective of the silicon-based process cutoff frequency bottoming out, realizes high-frequency high-power output, and adopts the on-chip micro-protrusion antenna as a wideband radiation structure with high radiation efficiency, high radiation intensity and directional radiation to realize energy radiation maximization.

[0028] The application fully utilizes the silicon process advantage, adopts an expandable array layout, and finally realizes a silicon-based terahertz radiation array source with high frequency and wide spectrum and high energy efficiency.

[0029] As Figures 1 to 4As shown, the scalable silicon-based terahertz radiation array source based on on-chip micro-convex antennas of this invention comprises array units consisting of cross-coupled transistors with drain and source inductors and on-chip micro-convex antennas as oscillators. The gates of adjacent array units are interconnected through transmission lines to form an array structure. The scalable silicon-based terahertz radiation array source based on on-chip micro-convex antennas includes multiple array units consisting of cross-coupled harmonic oscillators based on on-chip micro-convex antennas. The multiple array units are connected to form an n×n array structure.

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

[0031] In this application, the cross-coupling pairs mentioned are referred to as follows: Figure 1 As shown, M1 and M2 are two transistors in a cross-coupled pair, providing sufficient negative resistance to maintain oscillation in the oscillator structure and generating a differential oscillation signal at their drains; A1 is an on-chip micro-convex antenna, with the drains of the two transistors M1 and M2 connected to the differential feed terminals of the on-chip micro-convex antenna A1. In this application, the differential structure on-chip micro-convex antenna A1 has two functions: firstly, providing optimal load impedance to facilitate the extraction of the Nth harmonic; and secondly, radiating the signal.

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

[0033] In this configuration, the source of each transistor is connected to a source inductor L. s At one end, the drain of each transistor is connected to a drain inductor L. d At one end, the two source inductors are grounded, and the other end of the two drain inductors is connected to the differential feed terminal of the on-chip micro-convex antenna. The source inductors and drain inductors 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 n2These are the cross-coupled transistors of the 1st, 2nd, ..., nth array units, L d1 L d2 , ......, L dn L is the drain inductance of each unit. s1 L s2 , ......, L sn For each cell, L is the source inductance, and for each array cell, L is the source inductance. dn and L gn With coupling coefficient k n Coupled, 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, enhancing the driving capability of the oscillator and effectively increasing the maximum amplitude of the oscillator.

[0035] In this system, multiple array units are interconnected and extended through transmission lines connecting the gates of cross-coupled pairs of adjacent harmonic oscillators. The core circuit of each unit is locked at the fundamental frequency f0, forming a scalable silicon-based terahertz radiation array source with an n×n array structure. See [link to relevant documentation]. Figure 2 , Figure 3 as well as Figure 4 As shown.

[0036] in, Figure 2 , Figure 3 , Figure 4 The circuit diagrams show scalable silicon-based terahertz radiation array sources with 2×2, 3×3, and n×n array structures, respectively, each including 4, 9, and n array elements; each array element 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 VDD.

[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, radiated power, frequency modulation range, power consumption, and other performance requirements of the silicon-based terahertz source. Based on the adopted process, perform active device modeling, introduce passive embedded structures to improve the transistor structure and control its interconnection layout, thereby enhancing the circuit performance. max and DC-THz conversion efficiency.

[0039] (2) After the transistor size is determined, the single array unit is debugged, the on-chip micro-protruding antenna is taken as a load for impedance matching according to the actual extraction harmonic order requirement, the optimal load size is determined, the harmonic extraction is realized, and certain harmonic suppression function is possessed. In addition, the on-chip micro-protruding antenna is adjusted to have optimal radiation efficiency and radiation directivity, and the active part and the passive radiation structure are iterated until the optimal radiation state is reached.

[0040] (3) The multiple array units are combined, the frequency locking between the units is realized through the transmission line TL, and the radiation power of the whole system is enhanced. The different array sizes are verified, and the phase and amplitude of the single radiation unit are regulated and controlled, so that the radiation beam direction and shape are accurately controlled, thereby making the radiation beam shape and direction flexible to adjust, and improving the flexibility and performance of the system.

[0041] Referring to Figure 5 , the second aspect of the present application provides another on-chip micro-protruding antenna-based expandable silicon-based terahertz radiation source, which is a four-core coupled oscillator based on a double injection locking structure of an on-chip micro-protruding antenna, comprising one on-chip micro-protruding antenna and four cross-coupled pairs, each cross-coupled pair comprising two transistors M1 and M2, one end of a source inductance L s of each transistor being connected to a source of each transistor, one end of a drain inductance L d of each transistor being connected to a drain of each transistor, one end of a gate inductance L g of each transistor being connected to a gate of each transistor, the other end of the two source inductances of each cross-coupled pair being grounded, and the other end of the two drain inductances being connected to a differential feed-in end of the on-chip micro-protruding antenna.

[0042] The drain inductance of each cross-coupled pair is coupled to the source inductance of the adjacent cross-coupled pair with a first coupling coefficient, and the gate inductance between the adjacent cross-coupled pairs is coupled with a second coupling coefficient, so as to realize mutual injection locking between the cross-coupled pairs and enhance the fundamental frequency locking between the cross-coupled pairs through the two coupling structures.

[0043] The cross-coupling mode of the cross-coupled pair can refer to Figure 1 and the related description.

[0044] Specifically, as shown in Figure 5 , the transistors M1 and M2 are the cross-coupled pairs of each unit, the source, the gate and the drain thereof are connected to the source inductance L s , the gate inductance L g and the drain inductance L d respectively, A1 is the on-chip micro-protruding antenna, and is connected to the cross-coupled pair through the drain inductance L d . The drain inductance L dAll are coupled with the first coupling coefficient k1 and the adjacent core source inductance L s coupled, and the gate inductance L g Also all are coupled with the second coupling coefficient k2.

[0045] Wherein, in each cross-coupled pair, the drain ends of the two transistors generate differential Nth harmonic signals, according to the phase connection of adjacent cross-coupled pairs, 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 four-way connected Nth harmonic signals with a phase of 0° / 180° are used to drive the on-chip micro-protrusion antenna of the differential structure, and high-power Nth harmonic waves are radiated by the on-chip micro-protrusion antenna.

[0046] Wherein, the size and / or shape of the micro-protrusion antenna can be adjusted according to the best impedance matching to make it generate high-power Nth harmonic waves.

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

[0048] The four-core coupled oscillator based on the double-injection structure of the on-chip micro-protrusion antenna as described above has a circuit design mainly including the following steps:

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

[0050] (2) After determining the transistor size, debug the single core, according to the actual demand of extracting harmonic order, impedance match the on-chip micro-protrusion antenna as a load, determine the best load size, realize harmonic extraction, and have a certain harmonic suppression function. In addition, adjust the on-chip micro-protrusion antenna to have the best radiation efficiency and radiation directivity, and iterate the active part and the passive radiation structure until the best radiation state is reached.

[0051] At the same time, the double-injection structure is added, and the coupling inductance and the coupling coefficient are adjusted to realize the locking between the cores and the maximum amplitude output. And in the case of four-core coupling, the on-chip micro-protrusion antenna is readjusted to reach the best load condition, and the maximum radiation power is realized.

[0052] (3) The above four core coupled oscillators based on the double injection structure of the on-chip micro-convex antenna are combined and formed into an array, and the radiation power of the whole system is enhanced. Different array sizes are verified, and the phase and amplitude of a single radiation unit are adjusted to realize accurate control of the radiation beam direction and shape, so that the radiation beam shape and direction can be flexibly adjusted, and the system flexibility and performance are improved.

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

[0054] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0055] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments which can be understood by those skilled in the art.

Claims

1. Scalable silicon-based terahertz radiation source based on micro-ridged antennas on chip, characterized in that, The application discloses a four-core coupled oscillator based on a double-injection structure of an on-chip micro-antenna, which comprises an on-chip micro-antenna and four cross-coupled pairs, each of which comprises 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-coupled pair is grounded, the other end of the two drain inductors is connected to a differential feeding end of the on-chip micro-antenna, and the other end of the gate inductor is connected to the drain of another transistor. The drain inductor of each cross-coupled pair is coupled to the source inductor of an adjacent cross-coupled pair with a first coupling coefficient, and the gate inductor between the adjacent cross-coupled pairs is coupled with a second coupling coefficient, so that mutual injection locking between the cross-coupled pairs is realized through the two coupling structures, and frequency locking between the core circuits of the cross-coupled pairs at a fundamental frequency is enhanced.

2. The scalable silicon-based terahertz radiation source based on micro- horn antennas on chip according to claim 1, characterized in that, In each cross-coupled pair, the two transistors generate differential Nth harmonic signals at the drain ends, adjacent cross-coupled pairs are connected in phase, four Nth harmonic signals with a phase of 0° and four Nth harmonic signals with a phase of 180° are formed, and then a pair of differential signals synthesized by the four Nth harmonic signals with a phase of 0° / 180° is used to drive the on-chip micro-antenna in a differential structure, and high-power Nth harmonic signals are radiated by the on-chip micro-antenna, that is, radiation signals with a frequency of Nf0.

3. The scalable silicon-based terahertz radiation source based on micro-antenna on chip of claim 1, wherein, The four cross-coupled pairs have the same structure, the on-chip micro-antenna radiates high-power Nth harmonic signals, N represents the extraction harmonic order, and is determined by the impedance parameters of an output matching network formed by the on-chip micro-antenna.

4. The scalable silicon-based terahertz radiation source based on micro- horn antennas on chip according to claim 1, wherein, The first coupling coefficient and the second coupling coefficient are optimized to maximize the power of the Nth harmonic signals.

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