A terahertz detector circuit structure based on a resonant tunneling diode

Abstract

The present invention discloses a terahertz detector circuit structure based on a resonant tunneling diode, which belongs to the field of terahertz wireless communication. It comprises three parts: a resonant tunneling diode RTD, a low-pass filter and a biasing device BIASTEE. Among them, the resonant tunneling diode RTD acts as a nonlinear device to detect the received terahertz signal, the low-pass filter is mainly used to pass the detection signal and block the high-frequency carrier signal, and the biasing device BIASTEE is used for DC feeding and the passage of the detection signal. After adding a DC bias through the biasing device BIASTEE, the resonant tunneling diode RTD operates in the nonlinear region and detects and demodulates the received terahertz signal. The present invention has the advantages of simple structure, small size and low cost, and has important application value in the field of ultra-high-speed wireless communication.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz wireless communication, and in particular to a terahertz detector circuit structure based on a resonant tunneling diode. Background Art

[0002] Terahertz waves, covering the electromagnetic spectrum from 0.1THz to 10THz, have wavelengths ranging from 30μm to 3000μm. Early research into terahertz began in the 1970s. However, the lack of effective terahertz sources and detection technologies for many years limited the feasibility of terahertz wave communications, leading to the term "terahertz gap." However, with the advancement of ultrafast photonics and semiconductor technologies, the challenges of terahertz signal generation and detection have been gradually addressed, making terahertz wireless communications a growing research hotspot. Compared with other spectrum communications, the main advantages of terahertz communication are: 1) high data transmission rate and large capacity, which can reach tens or even hundreds of Gbps; 2) narrow beam, strong directionality, high confidentiality, and stronger anti-interference ability; 3) it has the ability to penetrate plasma, and can be used for plasma "blackout" blind spot communication when spacecraft re-enters the atmosphere and hypersonic aircraft communication; 4) it has the ability to penetrate sand, dust and smoke, and is suitable for close-range confidential communication in harsh environments; 5) terahertz communication systems are smaller than millimeter wave communication systems, and have very little attenuation outside the atmosphere, making them suitable for satellite communications, internal communications in spacecraft, etc.

[0003] In summary, wireless communication systems based on terahertz technology can meet the future communication requirements for fast, efficient, effective, accurate and diversified applications. They have extremely high prospects for practical engineering applications and also have important academic research significance.

[0004] There are two main approaches to implementing the receiver end of existing all-electronic terahertz communication systems: one is to use a superheterodyne system to convert the terahertz signal to an intermediate frequency before processing; the other is to directly detect and process the terahertz signal. Superheterodyne receivers typically consist of waveguide-packaged modules such as a local oscillator, a frequency multiplier, and a mixer. These systems are bulky, complex, and expensive. Direct detection, however, utilizes only a single detector to detect the terahertz signal, offering advantages such as simplicity and low cost. Currently, the most commonly used nonlinear device in electronic terahertz detectors is the Schottky diode. Compared to Schottky diodes, detectors using resonant tunneling diodes have higher sensitivity, enabling higher communication rates and longer transmission distances. Therefore, terahertz detectors based on resonant tunneling diodes have broad potential for development. Summary of the Invention

[0005] The purpose of the present invention is to provide a terahertz detector circuit structure based on a resonant tunneling diode. Compared with other types of detectors, it can reduce the complexity of terahertz communication systems, improve system reliability, improve system performance, reduce system costs, and support high-order modulation formats such as PAM4 amplitude modulation and demodulation.

[0006] In order to achieve the above invention, the present invention provides the following technical solutions:

[0007] A terahertz detector circuit structure based on a resonant tunneling diode (RTD) consists of three components: a resonant tunneling diode (RTD), a low-pass filter (LPF), and a biasing element (TEE). The RTD acts as a nonlinear device to detect the received terahertz signal. The LPF primarily passes the detection signal while blocking high-frequency carrier signals. The BIAS TEE biasing element provides DC power and allows the detection signal to pass.

[0008] The low-pass filter is used to filter the detection signal and prevent the high-frequency carrier signal from passing through. It is also used to perform impedance matching with the resonant tunneling diode nonlinear device to improve the detector performance.

[0009] The BIAS TEE is used to feed a DC signal into the resonant tunneling diode, pass the detection signal, and prevent the detection signal from leaking to the power supply system.

[0010] Preferably, the nonlinear device used is a resonant tunneling diode.

[0011] Preferably, the low-pass filter is composed of a metal-insulator-metal (MIM) capacitor and a short-circuit inductor.

[0012] Preferably, the bias device BIAS TEE is implemented by hybrid circuit integration or on-chip integration.

[0013] Preferably, the terahertz detector may use an on-chip integrated antenna to receive the terahertz signal or may use a waveguide to feed the terahertz signal.

[0014] Preferably, the terahertz signal modulation function can also be achieved by changing the bias voltage of the resonant tunneling diode.

[0015] Preferably, the short-circuit inductor can be implemented by using a microstrip line, a coplanar waveguide or a coplanar line.

[0016] Preferably, the on-chip integrated antenna is implemented in the form of a slot antenna, a bowtie antenna or a microstrip antenna.

[0017] The present invention has the following advantages and beneficial effects:

[0018] 1. The present invention provides a terahertz detector circuit structure based on a resonant tunneling diode, which directly detects and receives terahertz signals. Resonant tunneling diodes offer high frequency, low voltage, and nonlinear characteristics unaffected by thermal index. Compared to detectors based on Schottky diodes, resonant tunneling diodes offer superior sensitivity and are of great significance for detecting weak terahertz signals.

[0019] 2. The terahertz detector circuit structure based on the resonant tunneling diode provided by the present invention adopts a monolithic fully integrated approach and has the advantages of simple process and high reliability.

[0020] 3. The cost of the present invention is greatly reduced as the number of products increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are intended to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0022] Figure 1 Schematic diagram of a terahertz detector based on a resonant tunneling diode provided in an embodiment of the present invention.

[0023] Figure 2 This is the IV curve of the resonant tunneling diode of the present invention.

[0024] Figure 3 This is a schematic structural diagram of an embodiment of the circuit structure provided by the present invention.

[0025] Figure 4 Schematic diagram of a low-pass filter implementation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following describes the technical solutions of exemplary embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, and not all of them. The described embodiments are intended for illustration only and are not intended to limit the scope of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0027] Figure 1 FIG is a schematic diagram of a terahertz detector based on a resonant tunneling diode provided by an embodiment of the present invention. Figure 1 As shown, the terahertz detector based on the resonant tunneling diode provided in the embodiment includes three parts: a resonant tunneling diode, a low-pass filter and a biasing element BIAS TEE.

[0028] The resonant tunneling diode operates in a nonlinear region after being powered on, and is used for detecting terahertz signals.

[0029] The low-pass filter is used to filter the detection signal and prevent the high-frequency carrier signal from passing through. It is also used to perform impedance matching with the RTD nonlinear device to improve the detector performance.

[0030] The BIAS TEE is used to feed a DC signal into the resonant tunneling diode, pass the detection signal, and prevent the detection signal from leaking to the power supply system.

[0031] In this embodiment, the resonant tunneling diode has two nonlinear regions (a) and (b), such as Figure 2 shown.

[0032] Specifically, due to the electron energy distribution in the emitter of the resonant tunneling diode, the resonant tunneling of the tail electrons forms a nonlinear region (a), which is located in the starting area of the resonant tunneling current. The current density of the resonant tunneling diode in this region can be expressed by the thermal index j RTD To describe:

[0033]

[0034] Among them U RTD represents the bias voltage of the resonant tunneling diode, k represents the Boltzmann constant, T represents the temperature, and α = d / (d + l) represents the correlation coefficient, describing the bias voltage between the emitter and quantum well of the resonant tunneling diode. d and l represent the effective thicknesses of the emitter quantum well and collector quantum well, respectively. Excluding the correlation coefficient, the thermal index of the resonant tunneling diode is similar to that of the Schottky diode, resulting in a weaker nonlinearity in this region. Furthermore, the presence of space charge effects further weakens the nonlinearity of the resonant tunneling diode in this region.

[0035] Specifically, a nonlinear region (b) forms in the peak current region where the tunneling current begins to cut off as the bias voltage increases. This region has strong nonlinear characteristics. The nonlinear characteristics of this region are independent of the thermal index and are mainly related to the broadening of the quantum well tunneling subband. At room temperature, this broadening can be much smaller than kT ≈ 25 meV. Therefore, the detector based on the resonant tunneling diode has a higher sensitivity than the detector based on the Schottky diode. The maximum sensitivity of the detector based on the Schottky diode can be expressed as:

[0036]

[0037] Here, I′ represents the derivative of I(U). At room temperature, e / 2kT ≈ 20A / W. The nonlinearity of the resonant tunneling diode in region (b) is primarily related to the broadening of the quantum well tunneling subband and is not limited by current.

[0038] Figure 3: This is a schematic diagram of an embodiment of a detector circuit structure provided by the present invention. The circuit structure includes: a resonant tunneling diode RTD, a first inductor L1, a second inductor LTee, a first capacitor C1, and a second capacitor CTee, as follows:

[0039] In this embodiment, the first end of the RTD is connected to the first end of the first inductor L1, the second end of the first inductor L1, the first end of the first capacitor C1, the first end of the second capacitor CTee and the second end of the second inductor LTee are connected to each other, the second end of the RTD and the second end of the first capacitor C1 are connected to the negative terminal of the DC power supply, and the first end of the second inductor LTee is connected to the positive terminal of the DC power supply.

[0040] In this embodiment, the first capacitor C1 is a MIM capacitor, and the first inductor L1 is implemented in the form of a coplanar waveguide short-circuit line, and the two together form a low-pass filter. Figure 4 shown.

[0041] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the optimal embodiment of the present invention and does not limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A terahertz detector circuit structure based on a resonant tunneling diode, characterized in that: It includes three parts: resonant tunneling diode RTD, low-pass filter and bias BIAS TEE connected in series; After adding a DC bias through the bias breaker BIAS TEE, the resonant tunneling diode operates in the nonlinear region and detects and demodulates the received terahertz signal. The detected signal drives the subsequent load through a low-pass filter. The low-pass filter is used to filter the detection signal, prevent the high-frequency carrier signal from passing through, and is also used to perform impedance matching with the resonant tunneling diode RTD nonlinear device to improve the detector performance; The bias device BIAS TEE is used to feed a DC signal into the resonant tunneling diode, pass the detection signal, and prevent the detection signal from leaking to the power supply system.

2. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 1, characterized in that: The low-pass filter is composed of a metal-insulator-metal capacitor and a short-circuit inductor.

3. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 1, characterized in that: The bias device BIAS TEE is implemented by hybrid circuit integration or on-chip integration.

4. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 1, characterized in that: The terahertz detector uses an on-chip integrated antenna to receive terahertz signals or uses a waveguide to feed terahertz signals.

5. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 1, characterized in that: By changing the bias voltage of the resonant tunneling diode, the terahertz signal modulation function is achieved.

6. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 2, characterized in that: The short-circuit inductor is realized by using a microstrip line, a coplanar waveguide or a coplanar line.

7. The terahertz detector circuit structure based on a resonant tunneling diode according to claim 4, characterized in that: The on-chip integrated antenna is implemented in the form of a slot antenna, a bowtie antenna or a microstrip antenna.

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