A terahertz active frequency tripler based on InP technology

Abstract

The present invention discloses a terahertz active tripler based on InP process, comprising an input circuit, a terahertz transistor frequency doubling circuit and an output circuit connected in sequence; the input circuit comprises an input GSG probe, an input matching circuit and an input idle circuit connected in sequence, and the output circuit comprises an output fundamental idle circuit, an output second harmonic idle circuit, an output matching circuit and an output GSG probe connected in sequence. The input idle circuit and the output fundamental and second harmonic idle circuits constitute a band stop filter, wherein the fundamental idle circuit constitutes a fundamental band stop filter, and the output circuit of the present invention does not need to design a separate triple frequency bandpass coupling filter or a high-pass filter, thereby improving the utilization efficiency of the input fundamental wave and reducing the loss of the output triple frequency, and effectively improving the frequency doubling efficiency of the frequency multiplier. In addition, the entire frequency doubling circuit adopts a single-stage common source transistor circuit and is designed based on the InP process, so as to have better frequency and power characteristics.

Description

Technical Field

[0001] The invention relates to the technical field of millimeter wave communications, and in particular to a terahertz active tripler based on an InP process. Background Art

[0002] Terahertz communication technology is a potential key technology for future 6G communications. In millimeter wave and terahertz communication systems, it is a common method to obtain terahertz signals using a frequency doubling chain driven by a low-frequency source.

[0003] For the frequency multiplier, the input signal is a sinusoidal signal v in =V0cosw0t, the output current is:

[0004]

[0005] It can be seen from the above formula that the output signal contains a large number of harmonic components and DC components. After the output circuit is matched, the required signals can be filtered out and the unnecessary signals can be reflected by adding circuit structures such as filters, thereby increasing efficiency.

[0006] Passive frequency doublers implemented with Schottky diodes do not consume DC power, but they will generate conversion losses, require higher input power, and have low RF efficiency. Active frequency doublers have the advantages of relatively low input power, high RF conversion efficiency, and the ability to be monolithically integrated with other functional circuits. On the other hand, compared with the double frequency design, the triple frequency design is more difficult in the output filter structure; if a quarter-wavelength open parallel transmission line of the fundamental wave is used to achieve fundamental wave reflection, the equivalent input impedance of the parallel connection is Z in_eff =Z in / / Z in1 / 4 , where Z in1 / 4 =-jZ0cotβL≈0(L=λ / 4), due to the periodicity of the cot function, at the fundamental and third harmonic frequencies, Z in1 / 4 are close to zero, that is, Z in_eff The required third harmonic will also be filtered out. The traditional microstrip branch reflection cannot realize the function of the fundamental idle loop in the triple frequency circuit. At the same time, half-wavelength parallel coupled bandpass filter and high-pass filter are also often used as triple frequency output filters, but the circuit volume is large and will cause greater power loss. Summary of the invention

[0007] The object of the present invention is to provide a terahertz active tripler based on InP process with high radio frequency efficiency, low power loss and easy integration in view of the deficiencies of the prior art.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] A terahertz active tripler based on InP process, comprising an input circuit, a terahertz transistor frequency doubling circuit and an output circuit connected in sequence; the input circuit comprises an input GSG probe, an input matching circuit and an input idle circuit connected in sequence, the output circuit comprises an output fundamental idle circuit, an output second harmonic idle circuit, an output matching circuit and an output GSG probe connected in sequence, the terahertz transistor frequency doubling circuit is a single-stage common-source transistor circuit, and all circuits are manufactured based on InP process.

[0010] Furthermore, the input idle circuit is composed of a microstrip open-circuit branch with a length of 1 / 4 of the third harmonic wavelength to form a third harmonic band-stop filter, so that the generated third harmonic is reflected to the output, thereby improving radio frequency efficiency.

[0011] Furthermore, the input matching circuit is an L-type microstrip branch matching circuit, which is used to achieve matching from the GSG circuit to the input idle circuit.

[0012] Furthermore, the output second harmonic idle circuit is composed of a microstrip open-circuit branch with a length of 1 / 4 of the second harmonic wavelength to form a second harmonic band-stop filter, so that the generated second harmonic is reflected to the single-stage common-source transistor circuit, thereby improving the radio frequency efficiency.

[0013] Furthermore, the output fundamental wave idle circuit includes a microstrip line of relatively short length and a short-circuit capacitor connected to the microstrip line. The output fundamental wave idle circuit is used to reflect the fundamental wave to the single-stage common-source transistor circuit to improve the utilization efficiency of the fundamental wave.

[0014] Furthermore, the output matching circuit is an L-type microstrip branch matching circuit, which is used to achieve matching from the output GSG circuit to the output idle circuit.

[0015] Furthermore, the transistor used in the single-stage common-source transistor circuit is a high-speed electron mobility transistor, which has better frequency and power characteristics to meet the communication requirements of the terahertz frequency band.

[0016] Furthermore, the single-stage common-source transistor circuit also includes a bias circuit connected to the transistor, and the bias circuit is composed of a microstrip line and a fan-shaped microstrip structure to reduce radio frequency leakage.

[0017] The present invention has the following effects:

[0018] (1) The present invention realizes the idle circuit of the THz frequency band and the filtering and reflection circuit of the electromagnetic wave by connecting the microstrip line and the short-circuit capacitor, thereby improving the utilization efficiency of the input fundamental wave and reducing the loss of the output triple frequency, increasing the frequency multiplication efficiency and output power of the overall frequency multiplier, and reducing the layout area;

[0019] (2) The frequency multiplier based on InP technology uses a single-stage common-source InP HEMT transistor. In the THz frequency band, it has high output power and better RF conversion efficiency, and can be integrated with other circuits such as amplifiers and mixers on a single chip, solving the problem of large processing and assembly errors of traditional THz frequency multipliers and greatly reducing production costs.

[0020] (3) The output circuit based on InP process does not need to design a separate bandpass coupling filter or high-pass filter, which reduces the loss of the terahertz multiplier, which is beneficial to reducing the internal loss of the circuit and improving the RF efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the overall circuit diagram of the present invention;

[0022] Figure 2 It is a simulation diagram of input and output idle circuits;

[0023] Figure 3 Schematic diagram of InP process;

[0024] Figure 4 It is a schematic diagram of the transistor gate connection circuit based on InP process;

[0025] Figure 5 It is a schematic diagram of the transistor drain connection circuit based on InP process;

[0026] Figure 6 Figure 2 is the overall simulation efficiency and output power diagram. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0028] like Figures 1 to 6 As shown, the terahertz active tripler based on InP process provided in this embodiment includes an input circuit, a terahertz transistor frequency multiplication circuit and an output circuit connected in sequence; the input circuit includes an input GSG probe, an input matching circuit and an input idle circuit connected in sequence, the output circuit includes an output fundamental idle circuit, an output second harmonic idle circuit, an output matching circuit and an output GSG probe connected in sequence, and the terahertz transistor frequency multiplication circuit is a single-stage common source transistor circuit. The fundamental signal is input by the input GSG probe, passes through the input matching circuit and the input idle circuit, and then passes through the single-stage common source transistor circuit to generate various harmonics; the output current passes through the output fundamental idle circuit, the output second harmonic idle circuit and the output matching circuit, and finally the third harmonic is output through the output GSG probe.

[0029] In this embodiment, the input idle circuit is composed of a microstrip open-circuit branch with a length of 1 / 4 of the third harmonic wavelength to form a third harmonic band-stop filter, so that the generated third harmonic is reflected to the output, thereby improving the RF efficiency. The output idle circuit is composed of an output fundamental idle circuit and an output second harmonic idle circuit to form an output band-stop filter, wherein the output second harmonic idle circuit is a microstrip open-circuit branch with a length of 1 / 4 of the second harmonic wavelength, which constitutes a second harmonic band-stop filter, so that the generated second harmonic is reflected to a single-stage common source transistor circuit, thereby improving the RF efficiency. The output fundamental idle circuit is composed of a short branch connected to a short-circuit capacitor, and the output fundamental idle circuit is used to reflect the fundamental wave to a single-stage common source transistor circuit to improve the fundamental wave utilization efficiency. The input matching circuit and the output matching circuit are both L-type microstrip branch matching circuits, wherein the input matching circuit is used to achieve matching from the GSG circuit to the input idle circuit, and the output matching circuit is used to achieve matching from the output GSG circuit to the output idle circuit. The transistor used in the single-stage common-source transistor circuit is a high-speed electron mobility transistor, which has better frequency and power characteristics to meet the communication requirements of the terahertz frequency band. The output circuit of the present invention does not need to design a separate bandpass coupling filter or high-pass filter, thereby reducing the loss of the terahertz frequency multiplier, which is beneficial to reducing the internal loss of the circuit and improving the radio frequency efficiency.

[0030] Figure 2 This is a simulation diagram of the input and output idle circuits of this embodiment. By using circuit simulation software to perform impedance pulling on the transistor, the static operating voltage and input and output impedance of the highest triple frequency output power achieved by the corresponding transistor are obtained. By adding an idle loop circuit during pulling, the difficulty of subsequent design can be reduced.

[0031] In this embodiment, all circuits are designed based on the three-layer metal InP process. Figure 3 The figure is a simplified cross-sectional view of the process. The bottom of the figure is an InP substrate with a thickness of 70um, and on the InP substrate are metal zero layer M0, metal layer M1, metal layer M2, and through hole 1 and through hole 2 connecting the metal layers. The above substrate, metal layers and through holes constitute passive circuit structures such as microstrip circuits and MIM capacitors.

[0032] Figure 4 and Figure 5 This is a joint simulation structure model diagram of the field-circuit connection circuit of the transistor gate and drain. It is based on the InP process and includes the input circuit, output circuit and bias circuit in the transistor frequency multiplication circuit. The bias circuit is composed of a microstrip line with a length of one quarter wavelength and a fan-shaped microstrip structure to reduce RF leakage. The matching circuit design is optimized through joint simulation to obtain the best output RF efficiency and output power. Figure 6The simulated RF efficiency and output power diagram is shown. The simulation results show that the frequency doubling circuit produces a frequency doubling efficiency greater than 60% when the operating frequency is 212.4-230.3GHz.

[0033] The above description is only a preferred implementation manner of the present invention, but the protection scope of the present invention is not limited thereto, and any modification and replacement based on the technical solution and inventive concept provided by the present invention should be included in the protection scope of the present invention.

Claims

1. A terahertz active tripler based on InP technology, characterized in that: include An input circuit, a terahertz transistor frequency multiplication circuit and an output circuit connected in sequence; The input circuit includes an input GSG probe, an input matching circuit and an input idle circuit connected in sequence. The output circuit includes an output fundamental wave idle circuit, an output second harmonic idle circuit, an output matching circuit and an output GSG probe which are connected in sequence. The terahertz transistor frequency multiplication circuit is a single-stage common-source transistor circuit, and all circuits are manufactured based on the InP process; The input idle circuit is a microstrip open-circuit branch with a length of 1 / 4 of the third harmonic wavelength; The output second harmonic idle circuit is a microstrip open-circuit branch with a length of 1 / 4 of the second harmonic wavelength; The output fundamental wave idle circuit comprises a microstrip line and a short-circuit capacitor connected to the microstrip line.

2. The terahertz active tripler based on InP technology according to claim 1, characterized in that: The input matching circuit and the output matching circuit are L-type microstrip branch matching circuits.

3. The terahertz active tripler based on InP technology according to claim 1, characterized in that: The transistor used in the single-stage common-source transistor circuit is a high-speed electron mobility transistor.

4. The terahertz active tripler based on InP technology according to claim 1 or 3, characterized in that: The single-stage common-source transistor circuit also includes a bias circuit connected to the transistor, and the bias circuit is composed of a microstrip line and a fan-shaped microstrip structure.

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