Photo-generated local oscillator multi-band tuning millimeter wave mixing receiver device

Abstract

The invention relates to the technical field of terahertz signal receiving, in particular to a photo-generated local oscillator multi-band tuning millimeter wave mixing receiver device. The device comprises an antenna, a photo-generated local oscillator circuit, a broadband coherent frequency mixing circuit, a baseband signal processing platform, a PC control end and a time division multi-frequency tuning module. By introducing a photo-generated local oscillator technology, a millimeter wave local oscillator signal with high frequency, stability and low phase noise is obtained, and the adaptability of the system to multi-band and cross-band signals is improved. By adopting the broadband coherent odd harmonic mixer with the fin line structure, high-efficiency mixing of a radio frequency signal and a local oscillator signal is realized, and the broadband coherent odd harmonic mixer has the advantages of broadband, high-efficiency odd mixing, low loss, compact integration and the like. On the basis, a time division multi-frequency tuning technology is adopted, and dynamic tuning and switching of multi-frequency-band signals are achieved in a single receiving framework. According to the invention, the problems of frequency band switching bottleneck and multiplexing loss in a traditional multi-frequency receiving system are solved. The antenna has the advantages of being compact in structure, capable of covering multiple frequency bands, suitable for multi-frequency-band observation requirements in a high-sensitivity radiometer system and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz signal reception, and in particular to a photogenerated local oscillator multi-band tuned millimeter wave mixing receiver device, which can be applied to fields such as terahertz adaptive observation radiometers, radar imaging, astronomical observation, wireless communications, and material testing. Background Art

[0002] Millimeter-wave radiometers, with their unique advantages of high resolution and high sensitivity, play an irreplaceable role in key areas such as remote sensing, communications, medical imaging, and national defense security. In the millimeter-wave frequency band, electromagnetic waves possess remarkable atmospheric penetration and non-destructive detection properties, making them an increasingly important technology for high-performance passive detection systems. As the core component of a radiometer, the performance of the receiver directly determines the detection accuracy and sensitivity of the entire system.

[0003] Traditional receiver systems typically operate only at fixed frequencies and have a limited tuning range, making them incapable of meeting the practical needs of multi-band, wideband signal detection. In applications such as meteorological remote sensing and electromagnetic environment monitoring, traditional electronic receivers are limited by the local oscillator tuning bandwidth and mixer operating bandwidth, making flexible frequency switching and wideband coverage difficult. To address this issue, stacking multiple discrete receive chains is often required to achieve multi-band signal reception. This results in a complex system structure, low RF link reuse, and significantly increased power consumption and size, severely restricting system integration and engineering feasibility. Summary of the Invention

[0004] The object of the present invention is to provide a multi-band tuned millimeter wave mixing receiver device with optically generated local oscillators to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A photogenerated local oscillator multi-band tuned millimeter wave mixing receiver device, comprising: an antenna, a photogenerated local oscillator circuit, a broadband coherent mixing circuit, a baseband signal processing platform, a PC control terminal, and a time division multi-frequency tuning module;

[0007] The antenna is used to receive millimeter wave and terahertz radio frequency signals from space and send the received radio frequency signals to a broadband coherent mixing circuit;

[0008] The optically generated local oscillator circuit is used to generate a local oscillator signal and send the local oscillator signal to the broadband coherent mixing circuit;

[0009] The broadband coherent mixing circuit is used to mix the received radio frequency signal with the local oscillator signal to generate an intermediate frequency signal or a baseband signal;

[0010] The baseband signal processing platform is used to receive the intermediate frequency signal or baseband signal output by the broadband coherent mixing circuit, and amplify, filter and sample the intermediate frequency signal or baseband signal in sequence as a pre-processed digital received signal;

[0011] The PC control terminal and the time-division multi-frequency tuning module form a feedback control loop, wherein the PC control terminal collects and pre-processes the digital received signal, performs real-time spectrum analysis and demodulation on it, generates frequency band parameters including the optimal center frequency and bandwidth, and sends them to the time-division multi-frequency tuning module; based on the frequency band parameters, the time-division multi-frequency tuning module uses time division multiplexing technology to periodically generate feedback control signals to drive the optical local oscillator circuit to dynamically adjust the operating frequency band and bandwidth, thereby realizing adaptive frequency band switching and bandwidth control of the mixing receiver.

[0012] Furthermore, the photogenerated local oscillator circuit includes a tunable laser, a combiner, a single carrier photodiode (UTC-PD), a photogenerated local oscillator matching circuit, a choke local oscillator circuit, a first T-junction and a DC blocking capacitor; wherein the tunable laser is the input end of the photogenerated local oscillator circuit, connected to the time division multi-frequency tuning module; the isolation capacitor is the first output end of the photogenerated local oscillator circuit, connected to the broadband coherent mixing circuit; the choke local oscillator circuit is the second output end of the photogenerated local oscillator circuit, outputting a DC signal; the tunable laser is connected to the input end of the first T-junction via the combiner, the single carrier photodiode (UTC-PD), and the photogenerated local oscillator matching circuit in sequence, the first output end of the first T-junction is connected to the DC blocking capacitor; the second output end of the first T-junction is connected to the choke local oscillator circuit.

[0013] Furthermore, the tunable laser utilizes a distributed feedback laser (DFB), which is characterized by low noise and stability. The optical signal generated by the laser is transmitted via optical fiber to a single-carrier photodiode, where heterodyne mixing is performed to generate the desired local oscillator signal within the 30 GHz to 300 GHz frequency range.

[0014] Furthermore, the choke LO structure comprises a high-impedance transmission line with a length of one-quarter wavelength and two quarter-wavelength fan-shaped branches, which are used to prevent the local oscillator signal from being transmitted to the DC port. The local oscillator signal undergoes impedance transformation at the local oscillator frequency via the high-impedance transmission line. The two fan-shaped branches are connected in parallel at the end of the high-impedance transmission line (near the DC port) and are arranged symmetrically.

[0015] Furthermore, the DC blocking capacitor uses a quarter-wavelength coupled transmission line to prevent DC leakage from the local oscillator path to cause interference, thereby separating the paths of the local oscillator signal and the DC current, and only allowing the local oscillator signal to be loaded into the same-direction series Schottky diode pair circuit on the quartz substrate for mixing.

[0016] Furthermore, the broadband coherent mixing circuit includes a fin-line transition structure, an input matching circuit, a pair of Schottky diodes connected in series in the same direction, an output matching circuit, a second T-junction and an intermediate frequency low-pass filter; the fin-line transition structure is the first input end of the broadband coherent mixing circuit, the second input end of the second T-junction is the second input end of the broadband coherent mixing circuit, and the intermediate frequency low-pass filter is the output end of the broadband coherent mixing circuit; the fin-line transition structure is connected to the first input end of the second T-junction via the input matching circuit, the pair of Schottky diodes connected in series in the same direction, and the output matching circuit in sequence; the second input end of the second T-junction is connected to the first output end of the photogenerated local oscillator circuit, and the output end of the second T-junction is connected to the intermediate frequency low-pass filter.

[0017] Furthermore, in order to enable the radio frequency signal to be transmitted at high frequency and low loss, the fin line transition structure adopts a cosine gradient single-sided fin line.

[0018] Furthermore, the input matching circuit and the output matching circuit both adopt a suspended microstrip line structure, and the suspended microstrip line is a gold strip attached to a quartz substrate.

[0019] Furthermore, the intermediate frequency low-pass filter adopts a compact resonant unit structure, which is composed of two-stage I-shaped resonators, and is used to filter the local oscillator signal in the broadband coherent mixing circuit to prevent the local oscillator signal from leaking to the intermediate frequency output circuit, thereby ensuring that the local oscillator signal input and intermediate frequency signal output ports have high isolation.

[0020] Furthermore, the same-direction series Schottky diode pair includes a first Schottky diode and a second Schottky diode, both connected in series in the same direction, i.e., the cathode of the first diode is connected to the anode of the second diode. The entire structure has the anode of the first diode as the input end, and the cathode of the second diode as the output end, forming a same-direction series Schottky diode pair. The Schottky diodes are mounted on the suspended microstrip line in a flip-flop manner using conductive adhesive.

[0021] After adopting the above technical solution, the present invention has the following advantages:

[0022] 1. The present invention provides lower noise and wider frequency tuning range than traditional electronic local oscillators by using a tunable laser and a single-carrier photodiode (UTC-PD) to generate a local oscillator signal in a photogenerated local oscillator circuit;

[0023] 2. The present invention uses the intermediate frequency signal or baseband signal processed by the real-time spectrum analysis and demodulation of the PC control terminal to generate a feedback control signal through the time-division multi-frequency tuning module to tune the wavelength of the tunable laser. This can obtain the required local oscillator signal within a wide frequency range, allowing the receiver to automatically switch frequency bands within different time windows and tune as needed, achieving adaptive observation. This breaks through the problems of traditional frequency band switching and bandwidth limitations and improves the system's frequency band processing capabilities.

[0024] 3. This invention utilizes a broadband coherent mixing circuit based on odd harmonics to achieve efficient reception and frequency conversion of millimeter-wave and terahertz signals. Its application in radiometers enables higher-precision multi-band observations, meeting the high demands of scientific research and communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a system block diagram of the optically generated local oscillator multi-band tuned millimeter wave mixing receiver device of the present invention;

[0026] Figure 2 is a system block diagram of a broadband coherent mixing circuit according to an embodiment;

[0027] Figure 3 is a system block diagram of a photogenerated local oscillator circuit according to an embodiment;

[0028] Figure 4 1 is a structural diagram of a photogenerated local oscillator circuit and a broadband coherent mixing circuit according to an embodiment;

[0029] Figure 5 is a schematic diagram of a pair of Schottky diodes connected in series in the same direction according to an embodiment;

[0030] Figure 6 1 is a diagram showing simulation results of a broadband coherent mixing circuit based on odd harmonics according to an embodiment;

[0031] Figure 7 This is a diagram showing theoretical results of the optically generated local oscillator multi-band tuned millimeter wave mixing receiving device according to an embodiment;

[0032] Reference numerals:

[0033] 100 is a fin-line transition structure, 101 is an input matching circuit, 102 is a pair of Schottky diodes connected in series in the same direction, 103 is an output matching circuit, 104 is a second T-junction, 105 is a DC blocking capacitor, 106 is a choke local oscillator structure, 107 is a first T-junction, 108 is a photogenerated local oscillator matching circuit, 109 is a single-carrier photodiode, 110 is a combiner, 111 is an optical fiber, 112 is a tunable laser diode, and 113 is an intermediate frequency low-pass filter. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0035] Photogenerated local oscillator technology uses photonics to generate high-frequency local oscillator signals, offering the following advantages: It enables continuous tuning over an ultra-wideband, breaking through the bandwidth limitations of traditional electronic local oscillators; the tuning process is flexible and rapid, adapting to complex and changing multi-band detection requirements; and it simplifies the system structure, facilitating the miniaturization and integration of receivers. These advantages provide new solutions for wideband tuning and high-performance mixing in receiver systems. Compared to traditional electronic local oscillators, photogenerated local oscillators can achieve frequency tuning over a wider range and possess stronger multi-band adaptability, making them an ideal choice for implementing cross-band millimeter-wave receivers. Based on this, this embodiment provides a photogenerated local oscillator multi-band tuned millimeter-wave mixing receiver device, which effectively addresses the prominent issues of current receiver systems in terms of bandwidth, tuning capability, and integration.

[0036] like Figure 1 As shown, this embodiment provides a photogenerated local oscillator multi-band tuned millimeter wave mixing receiver device, including: an antenna, a photogenerated local oscillator circuit, a broadband coherent mixing circuit, a baseband signal processing platform, a PC control terminal, and a time division multi-frequency tuning module;

[0037] The antenna is a broadband radio frequency antenna, which is used to receive millimeter wave and terahertz radio frequency signals from space and send the received radio frequency signals to a broadband coherent mixing circuit.

[0038] The optically generated local oscillator circuit is used to generate a local oscillator signal and send the local oscillator signal to a broadband coherent mixing circuit. Figure 3 and Figure 4 As shown, the optical local oscillator circuit includes a tunable laser 112, an optical fiber 111, a combiner 110, a single carrier photodiode (UTC-PD) 109, an optical local oscillator matching circuit 108, a choke local oscillator circuit 106, a first T-junction 107 and a DC blocking capacitor 105; wherein: the tunable laser is the input end of the optical local oscillator circuit, connected to the time division multi-frequency tuning module; the isolation capacitor is the first output end of the optical local oscillator circuit, connected to the broadband coherent mixing circuit; the choke local oscillator circuit is the second output end of the optical local oscillator circuit, outputting a DC signal; the tunable laser is connected to the input end of the first T-junction via the combiner, the single carrier photodiode (UTC-PD), and the optical local oscillator matching circuit in sequence, the first output end of the first T-junction is connected to the DC blocking capacitor; the second output end of the first T-junction is connected to the choke local oscillator circuit.

[0039] The broadband coherent mixer circuit is used to mix a received radio frequency signal with a local oscillator signal to generate an intermediate frequency signal or convert it into a baseband signal. It supports broadband input from 110 GHz to 220 GHz and can process signals in the D and G bands. The broadband coherent mixer circuit includes a fin-line transition structure, an input matching circuit, a pair of Schottky diodes connected in series in the same direction, an output matching circuit, a second T-junction, and an intermediate frequency low-pass filter. The fin-line transition structure is the first input terminal of the broadband coherent mixer circuit and is connected to a broadband radio frequency antenna. The second input terminal of the second T-junction is the second input terminal of the broadband coherent mixer circuit, and the intermediate frequency low-pass filter is the output terminal of the broadband coherent mixer circuit. The fin-line transition structure is connected to the first input terminal of the second T-junction via the input matching circuit, the pair of Schottky diodes connected in series in the same direction, and the output matching circuit. The second input terminal of the second T-junction is connected to the first output terminal of the photogenerated local oscillator circuit, and the output terminal of the second T-junction is connected to the intermediate frequency low-pass filter.

[0040] The baseband signal processing platform is used to receive the intermediate frequency signal or baseband signal output by the broadband coherent mixing circuit, and amplify, filter and sample the intermediate frequency signal or baseband signal in sequence as a pre-processed digital received signal;

[0041] The PC control terminal and the time-division multi-frequency tuning module form a feedback control loop, wherein the PC control terminal collects and pre-processes the digital received signal, performs real-time spectrum analysis and demodulation on it, generates frequency band parameters including the optimal center frequency and bandwidth, and sends them to the time-division multi-frequency tuning module; based on the frequency band parameters, the time-division multi-frequency tuning module uses time division multiplexing technology to periodically generate feedback control signals to drive the optical local oscillator circuit to dynamically adjust the operating frequency band and bandwidth, thereby realizing adaptive frequency band switching and bandwidth control of the mixing receiver.

[0042] In the optically generated local oscillator circuit, the DC signal DC is used to apply a DC bias to the tunable laser 112. This laser uses two distributed feedback lasers (DFBs, with wavelengths λ1 and λ2, respectively). Its monolithic semiconductor cavity structure implements a feedback mechanism by integrating a Bragg grating in the active region to ensure single-mode output. Based on the dual-beam beat frequency method, by adjusting the wavelength difference between the two DFB lasers, the beat frequency signal generated by their interference can be used as a tunable local oscillator signal source. The specific formula is: where f LO is the frequency of the local oscillator signal, c is the speed of light (about 3×10 8 m / s), λ1 is the center wavelength of the first laser, and λ2 is the center wavelength of the second laser.

[0043] The optical signal generated by the tunable laser 112 is transmitted via optical fiber 111 to the single-carrier photodiode 109, where heterodyne mixing is performed to generate the desired local oscillator (LO) signal over a wide frequency range. This LO signal source exhibits low phase noise and improved frequency stability, significantly improving the accuracy and sensitivity of signal conversion. Because the DC signal and the LO signal coexist in this LO signal source, to prevent the LO signal from leaking to the DC port, a choke LO structure 106 and a DC blocking capacitor 105 are implemented after the optically generated LO matching circuit. The choke LO structure 106 prevents the LO signal from transmitting to the DC port, while the DC blocking capacitor 105 prevents DC leakage from the LO path. This separates the LO and DC signal paths, allowing only the LO signal to be loaded into the circuit of the same-direction series Schottky diode pair on the quartz substrate for mixing.

[0044] In a broadband coherent mixing circuit, after a broadband RF antenna receives millimeter-wave and terahertz RF signals, the RF signal received by the broadband RF antenna is coupled from free space to a planar circuit via a fin-line transition structure. The signal output by the fin-line transition structure is loaded onto a pair of Schottky diodes 102 in series in the same direction via an input matching circuit 101, causing it to be mixed with the local oscillator signal. The intermediate frequency output signal generated by the mixing is output to an intermediate frequency low-pass filter 113 via one end of a second T-junction 104. The intermediate frequency low-pass filter adopts a compact resonant unit structure, consisting of two stages of I-shaped resonators, and is used to filter the local oscillator signal in the broadband coherent mixing circuit, preventing the local oscillator signal from leaking into the intermediate frequency output circuit, thereby ensuring high isolation between the local oscillator signal input and intermediate frequency signal output ports. The substrate is a quartz substrate, and the various components in the circuit are connected by suspended microstrip lines.

[0045] In this embodiment, a time-division multi-frequency tuning module is connected to a PC control terminal to form a feedback circuit to tune and control the tunable laser. The resonance wavelength of the DFB is determined by the Bragg condition: B =2n eff Λ. Among them, λ B is the Bragg wavelength, that is, the resonance wavelength of the DFB laser, also known as the central emission wavelength, n effis the effective refractive index of the waveguide, and Λ is the grating period. The output wavelength of the laser is adjusted by changing the injection current of the tunable laser. Due to the carrier effect, an increase in the injection current will lead to an increase in the carrier concentration, which in turn affects the refractive index of the semiconductor material. A decrease in the refractive index will shorten the laser wavelength. Due to the temperature effect, an increase in current will cause the laser temperature to rise, and the thermo-optical effect of the material will increase the refractive index, which will cause the laser wavelength to lengthen. The wavelength of the DFB laser is mainly affected by the temperature effect, that is, increasing the injection current will increase the overall wavelength. In the photogenerated local oscillator circuit, current tuning can finely adjust the beat frequency range. By changing the magnitude of the injection current, the laser wavelength can be fine-tuned within a range of 0.4-1nm, which can tune the variation range corresponding to the local oscillator signal in third harmonic mixing.

[0046] The photogenerated local oscillator circuit can provide a stable broadband local oscillator signal. To avoid using multiple photodiodes to provide signals at different frequencies, the receiver can be applied to radiometers. Common radiometer frequencies are 118 GHz, 165 GHz, 183 GHz, and 229 GHz. Based on the radiometer design standards for satellite frequencies, the broadband coherent mixing circuit should meet the requirements of the 110-240 GHz frequency band. In this embodiment, the Schottky diode circuit is two Schottky diode pairs 102 connected in series in the same direction, which are mounted on the microstrip line in a flip-chip manner using conductive adhesive, as shown in FIG. Figure 5 As shown, two Schottky diodes are connected in series in the same direction. The RF signal is applied in the same direction relative to the diodes, while the local oscillator signal is applied through the transmission line between the two diode dies, flowing upward and downward toward the first and second diodes, respectively. The local oscillator signal is applied in opposite directions relative to the diodes. This removes the even harmonics of the local oscillator signal from the diodes, while retaining the odd harmonics, achieving odd-harmonic mixing. The specific derivation principle is as follows, and the current through the diodes can be expressed as the following formula.

[0047]

[0048] i2(t)=v RF (t) * g(t);

[0049] Where i1(t) represents the current through the first diode die; i2(t) represents the current through the second diode die; T represents the period of the local oscillator signal; V RF (t) represents the RF signal voltage loaded on the diode die; g(t) represents the small signal admittance function of the diode driven by the local oscillator signal.

[0050] The driving currents of the Schottky diodes in series are opposite to each other. Through Fourier transform, the following equation can be obtained:

[0051] I1(f)=VRF (f)*G(f)*e j2πfT / 2 ;

[0052] I2(f)=V RF (f)*G(f);

[0053] Where I1(f) is the frequency domain expression of the current in the first diode die (after Fourier transform), I2(f) is the frequency domain expression of the current in the second diode die, and V RF (f) is the frequency domain expression of the RF voltage signal, and G(f) is the Fourier transform of the diode admittance g(t). The local oscillator signal is taken as a standard sine function, and the frequency is the inverse of the period, that is, f LO =1 / T, then the two currents can be expressed as:

[0054]

[0055] Where m represents the harmonic order of the local oscillator signal; I3 is the mixed current, and the obtained real part of the current is the IF signal after the local oscillator signal and the RF signal are mixed.

[0056] When m is an odd number, through some algebraic transformations, we can get the following formula:

[0057] I m =V RF (f)*G(m*f LO );

[0058] I m =V RF (f)*G(m*f LO )m=(1,3,5,7…);

[0059]

[0060] Similarly, if m is an even number, through some algebraic transformations, we can get the following formula:

[0061]

[0062] I3(f)=0;

[0063] f IF = ±m*f LO ±n*f RF ;

[0064] Where n represents the harmonic order of the RF signal, f IF is the local oscillator signal frequency.

[0065] Based on the above analysis, even-order harmonics can be restricted to the diode pair loop by using a pair of diodes connected in series in the same direction. This allows the mixed output current to contain only odd-order harmonics. This structure also suppresses noise from the local oscillator because the fundamental frequency of the local oscillator is canceled during the mixing process, enabling odd-order mixing. This embodiment uses a third-harmonic circuit as an example.

[0066] The RF input uses a fin-line transition structure, transmitting a mixed mode consisting of TM and TE modes. The IF output uses a suspended microstrip line, transmitting quasi-TEM waves. These two waves are transmitted in different ways, resulting in high isolation between the local oscillator and the RF input. The mixed output passes through an IF low-pass filter, which filters the LO signal and ensures high isolation between the LO input and IF output ports.

[0067] Simulation is performed using the commercial 3D electromagnetic simulation software ADS:

[0068] The Schottky diode circuit of the embodiment is simulated in ADS simulation software, as shown in FIG. Figure 6 , the intermediate frequency output frequency is fixed at 1GHz, and the conversion loss of the third harmonic mixer is better than 10dB in the broadband range of 110GHz-200GHz, indicating that the third harmonic mixer can mix the stable broadband local oscillator signal provided by the optical local oscillator and meet the requirements of broadband mixing. In order to realize time-division multi-frequency tuning and realize multi-band reception and processing in the same receiver, the corresponding frequency range of 118(±5)GHz, 165(±5)GHz, 183(±10)GHz, and 229(±5)GHz is selected with reference to the satellite frequency design standard of the radiometer, so that the frequency band signal can be received in different time periods in the same channel. Combined with the above results, the theoretical results of the entire optical local oscillator multi-band tuning millimeter wave mixing receiver system are as follows: Figure 7 , achieving efficient reception of multi-band signals.

[0069] In summary, the present invention proposes a photogenerated local oscillator multi-band tuned millimeter-wave mixing receiver device. By introducing photogenerated local oscillator technology, a millimeter-wave local oscillator signal with high frequency stability and low phase noise is achieved, and a wide-band continuous tuning capability far exceeds that of electronic local oscillators is achieved, significantly improving the system's adaptability to multi-band and cross-band signals. Compared with the traditional method of splicing multiple sets of receiving chains, this solution greatly simplifies the RF architecture and improves the link multiplexing rate and system integration. At the same time, the photogenerated local oscillator has the advantages of strong frequency controllability, flexible switching, and adaptation to dynamic spectrum, which meets the needs of complex applications such as remote sensing monitoring and electromagnetic spectrum perception for broadband and high-sensitivity reception, and provides a new, efficient and flexible implementation path for millimeter-wave and terahertz receiving technologies.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be regarded as equivalent replacement methods and are included in the scope of protection of the present invention.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A multi-band tuned millimeter wave mixing receiver device with optically generated local oscillators, characterized in that: include: Antenna, photogenerated local oscillator circuit, broadband coherent mixing circuit, baseband signal processing platform, PC control terminal and time division multi-frequency tuning module; The antenna is used to receive millimeter wave / terahertz radio frequency signals from space and send the received radio frequency signals to a broadband coherent mixing circuit; The optically generated local oscillator circuit is used to generate a local oscillator signal and send the local oscillator signal to a broadband coherent mixing circuit; The broadband coherent mixing circuit is used to mix the received radio frequency signal with the local oscillator signal to generate an intermediate frequency signal or a baseband signal; The baseband signal processing platform is used to receive the intermediate frequency signal or baseband signal output by the broadband coherent mixing circuit, and amplify, filter and sample the intermediate frequency signal or baseband signal in sequence as a pre-processed digital received signal; The PC control terminal and the time-division multi-frequency tuning module form a feedback control loop, wherein the PC control terminal collects and pre-processes the digital received signal, performs real-time spectrum analysis and demodulation on it, generates frequency band parameters including the optimal center frequency and bandwidth, and sends them to the time-division multi-frequency tuning module; based on the frequency band parameters, the time-division multi-frequency tuning module uses time division multiplexing technology to periodically generate feedback control signals to drive the optical local oscillator circuit to dynamically adjust the operating frequency band and bandwidth, thereby realizing adaptive frequency band switching and bandwidth control of the mixing receiver.

2. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 1, characterized in that: The photogenerated local oscillator circuit includes a tunable laser, a combiner, a single-carrier photodiode, a photogenerated local oscillator matching circuit, a choke local oscillator circuit, a first T-junction and a DC blocking capacitor. The tunable laser is the input end of the photogenerated local oscillator circuit and is connected to a time-division multi-frequency tuning module. The isolation capacitor is the first output end of the photogenerated local oscillator circuit and is connected to a broadband coherent mixing circuit. The choke local oscillator circuit is the second output end of the photogenerated local oscillator circuit and outputs a DC signal. The tunable laser is connected to the input end of the first T-junction via the combiner, a single-carrier photodiode (UTC-PD) and the photogenerated local oscillator matching circuit in sequence. The first output end of the first T-junction is connected to the DC blocking capacitor. The second output end of the first T-junction is connected to the choke local oscillator circuit.

3. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 2, characterized in that: The tunable laser adopts a distributed feedback laser, which is used to generate an optical signal.

4. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 2, characterized in that: The choke local oscillator structure consists of a high-impedance transmission line with a length of one quarter wavelength and two one quarter wavelength fan-shaped branches. The two fan-shaped branches are connected in parallel to the ends of the high-impedance transmission line and are arranged symmetrically.

5. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 2, characterized in that: The DC blocking capacitors are coupled to a quarter wavelength transmission line.

6. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 1, characterized in that: The broadband coherent mixing circuit includes a fin-line transition structure, an input matching circuit, a pair of Schottky diodes connected in series in the same direction, an output matching circuit, a second T-junction, and an intermediate frequency low-pass filter; the fin-line transition structure is the first input end of the broadband coherent mixing circuit, the second input end of the second T-junction is the second input end of the broadband coherent mixing circuit, and the intermediate frequency low-pass filter is the output end of the broadband coherent mixing circuit; the fin-line transition structure is connected to the first input end of the second T-junction via the input matching circuit, the pair of Schottky diodes connected in series in the same direction, and the output matching circuit in sequence; the second input end of the second T-junction is connected to the first output end of the photogenerated local oscillator circuit, and the output end of the second T-junction is connected to the intermediate frequency low-pass filter.

7. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 6, characterized in that: The fin line transition structure adopts a cosine gradient single-sided fin line.

8. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 6, characterized in that: The input matching circuit and the output matching circuit both adopt a suspended microstrip line structure, and the suspended microstrip line is a gold strip attached to a quartz substrate.

9. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 6, characterized in that: The intermediate frequency low-pass filter adopts a compact resonance unit structure and is composed of two stages of I-shaped resonators.

10. The optically generated local oscillator multi-band tuned millimeter wave mixing receiver device according to claim 1, characterized in that: The same-direction series Schottky diode pair includes a first Schottky diode and a second Schottky diode, wherein the cathode of the first diode is connected to the anode of the second diode.

Images