Frequency mixer and signal transmission device

Abstract

The present application relates to the technical field of communications, and provides a frequency mixer and a signal transmission device. In the solution provided by the present application, the frequency mixer can transmit a local oscillator signal by means of a slot line, and transmit a first signal, a second signal and a third signal by means of microstrip lines. Thus, it can be ensured that the transmission mode of the local oscillator signal is different from the transmission mode of the first signal, and different from the transmission modes of the second signal and of the third signal, that is, the transmission mode of the local oscillator signal can be distinguished from the transmission mode of the first signal, and distinguished from the transmission modes of the second signal and of the third signal. Since the transmission mode of the local oscillator signal is distinguished from the transmission modes of the other signals, the leakage of the local oscillator signal to other signal ports can be effectively reduced, thereby effectively improving the performance of the frequency mixer.

Description

Mixers and signal transmission equipment

[0001] This application claims priority to Chinese patent application No. 202310994122.6 filed on August 8, 2023, entitled “Mixer and Signal Transmission Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a mixer and a signal transmission device. Background Art

[0003] Mixers are key components used for frequency conversion in microwave systems. In a receiver, a mixer mixes a received RF signal with a local oscillator (LO) signal to produce an intermediate frequency (IF) or baseband signal. In a transmitter, a mixer mixes a baseband signal (or IF) with a LO signal to produce an RF signal.

[0004] However, when mixing signals of different frequencies, the local oscillator (LO) signal may leak to other signal ports of the mixer, such as the RF signal port. This is known as local oscillator (LO) leakage, which can severely impact receiver and transmitter performance.

[0005] Summary of the Invention

[0006] The present application provides a mixer and a signal transmission device, which can solve the technical problem of serious local oscillator leakage of the mixer.

[0007] In a first aspect, a mixer is provided, comprising: a core circuit, a slot line, a first microstrip line, a second microstrip line, and a third microstrip line. The slot line, the first microstrip line, the second microstrip line, and the third microstrip line are all connected to the core circuit. The slot line is used to transmit a local oscillator signal to the core circuit, the first microstrip line is used to transmit a first signal at a first frequency, the second microstrip line is used to transmit a second signal at a second frequency, and the third microstrip line is used to transmit a third signal at the second frequency. The second frequency is different from the first frequency, and the third signal has an opposite phase to the second signal. The core circuit is used to achieve frequency conversion between the first and second frequencies based on the local oscillator signal.

[0008] The mixer provided in this application is capable of transmitting a local oscillator signal via a slotted line and transmitting a first signal and a second signal via a microstrip line. This ensures that the transmission mode of the local oscillator signal is different from that of the first signal, and different from the transmission modes of the second and third signals. That is, the local oscillator signal can be isolated from the transmission modes of the first signal, and from the transmission modes of the second and third signals. Because the transmission modes of the local oscillator signal are isolated from those of other signals, leakage of the local oscillator signal at other signal ports can be effectively reduced, thereby effectively improving the performance of the mixer.

[0009] Optionally, the core circuit may include: a first transistor and a second transistor, wherein a first electrode of the first transistor is connected to a first electrode of the second transistor; one side of the slot line is connected to a gate of the first transistor, and the other side of the slot line is connected to a gate of the second transistor; a first microstrip line is connected to the first electrode of the first transistor, the second microstrip line is connected to the second electrode of the first transistor, and the third microstrip line is connected to the second electrode of the second transistor.

[0010] It is understood that the slot line is composed of two spaced metal plates (or metal lines), one side of the slot line refers to one of the metal plates (or metal lines), and the other side of the slot line refers to the other metal plate (or metal line). It is also understood that the first electrode of the transistor can be one of the source and drain electrodes, and the second electrode can be the other of the source and drain electrodes.

[0011] The two sides of the slot line are connected to the gates of the two transistors, enabling differential feeding of the local oscillator signal. This means that the local oscillator signal fed into the core circuit is a differential signal. This dual-gate feed structure ensures that even if the local oscillator signal leaks to other signal ports of the mixer (such as the RF signal port), the leaked signals are in opposite phases and their energy cancels out, effectively improving local oscillator suppression.

[0012] Optionally, the first transistor and the second transistor may both be field effect transistors. Using field effect transistors as the nonlinear unit of the mixer can ensure high linearity.

[0013] The field effect transistor may be a transistor with high electron mobility and low knee voltage, so as to further ensure that the frequency conversion efficiency and linearity of the mixer are both high.

[0014] Optionally, the slot line, the gate of the first transistor, and the gate of the second transistor may all be located in the same layer and may be made of the same metal material, thereby effectively simplifying the manufacturing process of the mixer and improving the manufacturing efficiency of the mixer.

[0015] Optionally, the strip conductor of the first microstrip line, the strip conductor of the second microstrip line, the strip conductor of the third microstrip line, the first pole and the second pole of the first transistor, and the first pole and the second pole of the second transistor can all be located in the same layer and can be made of the same metal material.

[0016] It is understood that the microstrip line can include a strip conductor located on top of a dielectric substrate and a ground (GND) plane located below the dielectric substrate. In the solution provided in this application, the slot line, the strip conductors of each microstrip line, and each electrode of the transistor can be located on the same layer and can be made of the same metal material. This can effectively simplify the preparation process of the mixer and improve the preparation efficiency of the mixer.

[0017] Optionally, the mixer may further include a fourth microstrip line connected to the slotline and configured to transmit a local oscillator signal to the slotline. The local oscillator signal transmitted by the fourth microstrip line may be a single-ended signal, which, after being fed into the slotline, can be converted into a differential signal. In other words, the transmission mode of the local oscillator signal can be switched from the microstrip line's primary transmission mode to the slotline's primary transmission mode, thereby achieving a change in the electromagnetic field transmission mode.

[0018] Optionally, the slot line may also be directly connected to the local oscillator port and used to receive the local oscillator signal output by the local oscillator port. The local oscillator signal output by the local oscillator port is a differential signal.

[0019] By directly feeding in the differential local oscillator signal, there is no need to transmit the local oscillator signal from the microstrip line to the slot line and convert the signal transmission mode, which can effectively simplify the structure of the mixer.

[0020] Optionally, the first signal may be a radio frequency signal, and the second and third signals may both be intermediate frequency signals; alternatively, the first signal may be an intermediate frequency signal, and the second and third signals may both be radio frequency signals. Accordingly, the mixer can perform frequency conversion between radio frequency signals and intermediate frequency signals. The intermediate frequency signal may also include a zero intermediate frequency signal, i.e., a baseband signal. In other words, the mixer can be used in a zero intermediate frequency architecture.

[0021] Optionally, the first microstrip line can be used to transmit a first signal to the core circuit, the second microstrip line is used to transmit a second signal output by the core circuit, and the third microstrip line is used to transmit a third signal output by the core circuit. That is, the first signal can be an input signal, and the second and third signals can both be output signals.

[0022] Alternatively, the first microstrip line is used to transmit a first signal output by the core circuit, the second microstrip line is used to transmit a second signal to the core circuit, and the third microstrip line is used to transmit a third signal to the core circuit. In other words, the second and third signals can both be input signals, and the first signal can be an output signal.

[0023] It is understood that if an RF signal is the input signal and an IF signal is the output signal, the mixer is used to down-convert the RF signal, that is, the mixer can operate as a downconverter. In this case, the input RF signal can drive the transistors in the mixer core circuit to generate channel current.

[0024] If an IF signal is input and an RF signal is output, the mixer is used to upconvert the IF signal, meaning it can function as an upconverter. In this case, the input IF signal drives the transistors in the mixer's core circuit to generate channel current.

[0025] Optionally, the mixer may further include: at least one of a first frequency selection circuit, a second frequency selection circuit, a third frequency selection circuit, and a fourth frequency selection circuit, wherein the first frequency selection circuit is connected to the slot line, the second frequency selection circuit is connected to the first microstrip line, the third frequency selection circuit is connected to the second microstrip line, and the fourth frequency selection circuit is connected to the third microstrip line.

[0026] If the mixer includes a fourth microstrip line, the first frequency selection circuit can be connected to the slot line via the fourth microstrip line. The first frequency selection circuit can achieve matching of the local oscillator signal and open circuiting of the first, second, and third signals. The second frequency selection circuit can achieve matching of the first signal, open circuiting of the local oscillator signal, and short circuiting of the second and third signals. The third and fourth frequency selection circuits can achieve matching of the second and third signals, open circuiting of the local oscillator signal, and short circuiting of the first signal.

[0027] In the solution provided by this application, since the local oscillator signal is isolated from the transmission mode of the first signal, and from the transmission modes of the second and third signals, the complexity of matching each signal port of the mixer can be effectively reduced, eliminating the need for a high-suppression frequency selection circuit for each signal port. This effectively reduces the structural complexity and area of ​​each frequency selection circuit, thereby saving chip area and cost of the mixer. For example, compared to using microstrip lines to transmit the local oscillator signal, the first signal, the second signal, and the third signal, the mixer provided in the embodiment of this application can save approximately 30% in both area and cost.

[0028] In a second aspect, a signal transmission device is provided. The signal transmission device may include: an antenna; and a mixer as provided in the first aspect. The mixer is configured to perform frequency conversion on a signal received by the antenna, and / or the mixer is configured to transmit the frequency-converted signal to the antenna for radiation from the antenna.

[0029] If the mixer is an upconverter, it can upconvert a baseband signal or an intermediate frequency signal into an RF signal and transmit the RF signal to the antenna for antenna radiation. If the mixer is a downconverter, it can downconvert the RF signal received by the antenna into an intermediate frequency signal or a baseband signal. Because the mixer provided in the above aspects can effectively suppress leakage of the local oscillator signal, it can ensure good signal transmission performance of the signal transmission device.

[0030] In summary, the present application provides a mixer and signal transmission device, which can transmit a local oscillator signal through a slot line and transmit a second signal and a third signal through a microstrip line. As a result, it can be ensured that the transmission mode of the local oscillator signal is different from the transmission mode of the first signal, and different from the transmission modes of the second signal and the third signal. In other words, it is possible to achieve isolation of the transmission mode of the local oscillator signal from the first signal, and isolation of the transmission mode of the local oscillator signal from the transmission mode of the second signal and the third signal. Since the local oscillator signal is isolated from the electromagnetic field signal transmission mode of other signals, it is possible to effectively reduce the leakage of the local oscillator signal at other signal ports, thereby effectively improving the performance of the mixer. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic structural diagram of a signal transmission device provided in an embodiment of the present application;

[0032] FIG2 is a schematic structural diagram of a mixer provided in an embodiment of the present application;

[0033] FIG3 is a schematic diagram of a transmission mode of each signal in a mixer provided in an embodiment of the present application;

[0034] FIG4 is a schematic structural diagram of a core circuit of a mixer provided in an embodiment of the present application;

[0035] FIG5 is a schematic structural diagram of another mixer provided in an embodiment of the present application;

[0036] FIG6 is a schematic structural diagram of another mixer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] The mixer and signal transmission device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0038] The mixer provided in the embodiments of the present application can be applied to a signal transmission device, which can be used to transmit microwave signals and is therefore also referred to as a microwave transmission device. For example, the signal transmission device can be used to transmit radio frequency signals, that is, the signal transmission device can be a radio frequency receiver, a radio frequency transmitter, or a radio frequency transceiver.

[0039] Figure 1 is a structural diagram of a signal transmission device provided in an embodiment of the present application, and Figure 1 takes the signal transmission device as an example of a radio frequency transceiver device for explanation. As shown in Figure 1, the signal transmission device may include: an antenna 01, a receiving chain 02 and a transmitting chain 03. Among them, the receiving chain 02 may include: an amplifier 021, a filter 022, a mixer 023 and an analog to digital converter (ADC) 024. The amplifier 021 may be a low noise amplifier (LNA), which is used to amplify the radio frequency (RF) signal received by the antenna 01. The filter 022 is used to filter the radio frequency signal. The mixer 023 is used to down-convert the radio frequency signal based on the local oscillator (LO) signal to obtain an intermediate frequency (IF) signal or a baseband signal. The ADC 024 is used to perform analog-to-digital conversion on the analog signal output by the mixer 023 to obtain a digital signal, and transmit the converted digital signal to the baseband chip (not shown in the figure).

[0040] Continuing with reference to Figure 1, the transmission chain 03 may include an amplifier 031, a filter 032, a mixer 033, and a digital-to-analog converter (DAC) 034. DAC 034 is used to perform digital-to-analog conversion on the digital baseband signal to be transmitted by the baseband chip to obtain an analog baseband signal. Mixer 033 is used to up-convert the analog baseband signal based on the local oscillator signal to obtain a radio frequency signal. Filter 032 is used to filter the radio frequency signal. Amplifier 031 may be a power amplifier (PA), which is used to amplify the power of the received radio frequency signal and transmit the power-amplified radio frequency signal to antenna 01. Antenna 01 can then radiate the received radio frequency signal.

[0041] The antenna 01 may include a receiving antenna and a transmitting antenna. The receiving antenna is connected to the receiving link 02 and is used to receive radio frequency signals transmitted by other devices. The transmitting antenna is connected to the transmitting link 03 and is used to radiate radio frequency signals into space.

[0042] It is understood that the signal transmission device provided in the embodiment of the present application may be a signal receiving device (also referred to as a receiver), and accordingly, the signal transmission device may not include the transmission link 03. Alternatively, the signal transmission device provided in the embodiment of the present application may be a signal transmitting device (also referred to as a transmitter), and accordingly, the signal transmission device may not include the receiving link 02.

[0043] It is also understood that the receiving chain 02 and / or transmitting chain 03 in the signal transmission device may further include other signal processing devices, such as a larger number of amplifiers, filters, and / or mixers. Of course, the number of signal processing devices included in the receiving chain 02 and / or transmitting chain 03 may also be reduced based on the requirements of the application scenario, and the connection relationship between the signal processing devices may also be flexibly adjusted based on the requirements of the application scenario, which is not limited in this embodiment of the present application.

[0044] For example, if the signal transmission device adopts a zero intermediate frequency (IF) architecture, mixer 023 and mixer 033 can implement frequency conversion between the RF signal and the baseband signal. If the signal transmission device adopts a superheterodyne architecture, both the receiving chain 02 and the transmitting chain 03 can include at least two mixers, one of which can be used to implement frequency conversion between the RF signal and the IF signal, and the other mixer can be used to implement frequency conversion between the IF signal and the baseband signal.

[0045] For the receive link, if a zero-IF architecture is used, in a 1+1 module hot backup scenario, the backup module's local oscillator signal may be fed to the active module's receiver via the combiner, causing co-channel interference and, in turn, affecting receiver sensitivity. 1+1 module hot backup can refer to deploying a primary and a backup receiver in the system. The backup module can refer to the backup receiver, and the active module can refer to the primary receiver.

[0046] In the transmit chain, local oscillator (LO) signal leakage can affect transmit detection power accuracy, requiring additional orthogonal modulation compensation (QMC) algorithm correction or equipment calibration to improve device performance. Based on the above analysis, hardware solutions that reduce or suppress LO signal leakage are crucial for improving the performance of signal transmission equipment.

[0047] In some embodiments, an image rejection mixer can achieve 180-degree reverse cancellation of two image signals through two 90-degree bridges at the RF and IF frequencies. Although this image rejection mixer can suppress image interference energy, it cannot suppress local oscillator leakage.

[0048] In some other embodiments, LO rejection mixers can offset LO power at the RF port by shifting the LO signal by 180 degrees, providing additional LO signal rejection. However, the core circuitry of these mixers lacks LO signal rejection and cannot effectively suppress LO signal leakage.

[0049] The core circuit of the mixer refers to a nonlinear circuit in the mixer for achieving frequency conversion, which may include one or more nonlinear elements. The area where the core circuit is located may also be called the core area.

[0050] Figure 2 is a schematic diagram of the structure of a mixer provided in an embodiment of the present application. This mixer can be used in a signal transmission device such as that shown in Figure 1. For example, the mixer can be used to mix a local oscillator signal with a radio frequency signal to obtain an intermediate frequency signal; alternatively, the mixer can be used to mix a local oscillator signal with an intermediate frequency signal to obtain an radio frequency signal. The mixer provided in an embodiment of the present application can effectively reduce the leakage of the local oscillator signal and improve device performance.

[0051] As shown in FIG2 , the mixer may include a core circuit 10, a slot line 20, a first microstrip line 30, a second microstrip line 40, and a third microstrip line 50. The slot line 20, the first microstrip line 30, the second microstrip line 40, and the third microstrip line 50 are all connected to the core circuit 10.

[0052] In an embodiment of the present application, the slot line 20 can be used to transmit a local oscillator signal to the core circuit 10, the first microstrip line 30 can be used to transmit a first signal at a first frequency, the second microstrip line 40 can be used to transmit a second signal at a second frequency, and the third microstrip line 50 can be used to transmit a third signal at the second frequency. The core circuit 10 can be used to perform frequency conversion between a first frequency and a second frequency based on the received local oscillator signal. The second frequency is different from the first frequency, and the third signal has an opposite phase to the second signal, i.e., the phase difference between the third signal and the second signal can be 180 degrees.

[0053] As an optional implementation, the first microstrip line 30 can be used to transmit a first signal to the core circuit 10, the second microstrip line 40 can be used to transmit a second signal output by the core circuit 10, and the third microstrip line 50 can be used to transmit a third signal output by the core circuit 10. In other words, the first signal can be an input signal, and the second and third signals can both be output signals. Accordingly, the core circuit 10 can mix the local oscillator signal with the first signal to obtain the second and third signals.

[0054] As another optional implementation, the first microstrip line 30 can be used to transmit the first signal output by the core circuit 10, the second microstrip line 40 can be used to transmit the second signal to the core circuit 10, and the third microstrip line 50 can be used to transmit the third signal to the core circuit 10. In other words, the second and third signals can both be input signals, and the first signal can be the output signal. Accordingly, the core circuit 10 can mix the local oscillator signal, the second signal, and the third signal to obtain the first signal.

[0055] It is understood that the first frequency may be greater than the second frequency. For example, the first signal may be a radio frequency signal, and the second and third signals may both be intermediate frequency signals. Alternatively, the first frequency may be less than the second frequency. For example, the first signal may be an intermediate frequency signal, and the second and third signals may both be radio frequency signals.

[0056] In an embodiment of the present application, if a radio frequency signal is an input signal and an intermediate frequency signal is an output signal, the mixer can downconvert the radio frequency signal based on a local oscillator signal to obtain an intermediate frequency signal. Accordingly, the mixer can be a downconverter. Alternatively, if the intermediate frequency signal is an input signal and a radio frequency signal is an output signal, the mixer can upconvert the intermediate frequency signal based on a local oscillator signal to obtain a radio frequency signal. Accordingly, the mixer can be an upconverter.

[0057] It is also understood that the intermediate frequency signal in the embodiments of the present application may also include a zero intermediate frequency signal, i.e., a baseband signal. In other words, the mixer can achieve frequency conversion between an RF signal and a baseband signal, i.e., the mixer can also be used in a zero intermediate frequency architecture. If the mixer is used to achieve frequency conversion between an RF signal and an intermediate frequency signal, or between an intermediate frequency signal and a baseband signal, then the mixer can be used in a superheterodyne architecture.

[0058] FIG3 is a schematic diagram of the transmission modes of various signals in a mixer provided in an embodiment of the present application. As shown in FIG3 , within the region where the core circuit 10 is located (i.e., the core region of the mixer), the local oscillator signal is transmitted using the slotline dominant mode, while the first, second, and third signals (i.e., the RF signal and the IF signal) are transmitted using the microstrip dominant mode. Within the region where the core circuit 10 is located, the electric field distribution of the local oscillator signal can be shown as the dotted arrows in FIG4 .

[0059] Combining Figures 3 and 4 shows that the electromagnetic field transmission mode of the local oscillator signal is orthogonal to the transmission mode of the RF signal and the transmission mode of the intermediate frequency signal. This ensures that the local oscillator signal does not couple with the RF signal or the intermediate frequency signal. In other words, the local oscillator signal is energy-isolated from other signals, effectively reducing local oscillator leakage in the mixer core.

[0060] Table 1 shows the test results obtained by simulation testing of an image rejection mixer, a local oscillator rejection mixer, and a mixer provided by an embodiment of the present application. As shown in Table 1, in the 80 GHz frequency band, neither the image rejection mixer nor the local oscillator rejection mixer can achieve isolation of the local oscillator signal in the core area of ​​the mixer, that is, the local oscillator isolation of both is 0 decibel (dB). However, the mixer provided by an embodiment of the present application can improve the isolation by more than 10 dB. Based on the simulation results, it can be seen that the mixer provided by an embodiment of the present application has a good local oscillator suppression effect in the core area, which can effectively reduce the leakage of the local oscillator signal.

[0061] Table 1

[0062] In summary, embodiments of the present application provide a mixer capable of transmitting a local oscillator signal via a slotline and transmitting a first signal, a second signal, and a third signal via a microstrip line. This ensures that the transmission mode of the local oscillator signal is different from the transmission mode of the first signal, and different from the transmission modes of the second and third signals. That is, mode isolation of the local oscillator signal from the first signal, as well as mode isolation of the local oscillator signal from the second and third signals, can be achieved. Because the local oscillator signal is isolated from the electromagnetic field transmission mode of other signals, leakage of the local oscillator signal at other signal ports can be effectively reduced, thereby effectively improving the performance of the mixer.

[0063] Figure 4 is a schematic diagram of the structure of a core circuit provided in an embodiment of the present application. As shown in Figure 4, core circuit 10 may include: a first transistor 101 and a second transistor 102. The first electrode of first transistor 101 is connected to the first electrode of second transistor 102, and the common terminal formed by the first electrodes of the two transistors can be represented as G0 in Figure 4.

[0064] FIG5 is a schematic diagram of a partial structure of a core circuit provided in an embodiment of the present application. As can be seen from FIG4 and FIG5 , one side 201 of the slot line 20 can be connected to the gate G1 of the first transistor 101, and the other side 202 of the slot line 20 can be connected to the gate G2 of the second transistor 102. Furthermore, the first microstrip line 30 can be connected to the first electrode of the first transistor 101, that is, the first microstrip line 30 can be connected to the common terminal G0 of the two transistors. The second microstrip line 40 can be connected to the second electrode G3 of the first transistor 101, and the third microstrip line 50 can be connected to the second electrode G4 of the second transistor 102.

[0065] It is understood that the slot line 20 is composed of two spaced metal plates (or metal wires), one side 201 of the slot line 20 refers to one of the metal plates (or metal wires), and the other side 202 of the slot line 20 refers to the other metal plate (or metal wire). It is also understood that the first electrode of the transistor can be one of the source and drain electrodes, and the second electrode can be the other of the source and drain electrodes, which is not limited in this embodiment of the present application.

[0066] Optionally, in the embodiment of the present application, the first transistor 101 and the second transistor 102 may both be field effect transistors (FETs). Using FETs as the nonlinear unit of the mixer can ensure high linearity of the mixer.

[0067] The first transistor 101 and the second transistor 102 may also be FETs with high electron mobility and low knee voltage, so as to further ensure high frequency conversion efficiency and linearity of the mixer.

[0068] As shown in Figure 4, the first transistor 101 and the second transistor 102 can be formed on a substrate, which can be a gallium arsenide (GaAs) substrate. In addition, the transistor can also include an epitaxial layer, a barrier layer, and an electrode layer sequentially formed on the substrate. Among them, the epitaxial layer can be GaAs epitaxial to ensure better material consistency. The material of the barrier layer can be aluminum gallium arsenide (ALGaAs). The material of the electrode layer can be a metal material, and the electrode layer can include the gate, the first pole, and the second pole of the transistor. In addition, a heavily doped GaAs layer can be formed between the electrode layer and the barrier layer.

[0069] Continuing with Figure 4, a two-dimensional electron gas (2DEG) is also formed in the epitaxial layer, which also forms the depletion region of the transistor, i.e., the channel region. A local oscillator signal is applied to the two sets of gates via a planar slot line 20, thereby controlling the channel state of the two transistors. Alternatively, it can be understood that the voltage of the slot line 20 can control the channel state of the transistor.

[0070] In the embodiment of the present application, when the mixer operates as an upconverter, the intermediate frequency signal and the local oscillator signal are input signals, and the radio frequency signal is the output signal. In this case, the intermediate frequency signal can drive the first transistor 101 and the second transistor 102 to generate a channel current. When the mixer operates as a downconverter, the radio frequency signal and the local oscillator signal are input signals, and the intermediate frequency signal is the output signal. In this case, the radio frequency signal can drive the first transistor 101 and the second transistor 102 to generate a channel current.

[0071] As can be understood, referring to Figure 3 , the first microstrip line 30 can be used to transmit the radio frequency signal RF, the second microstrip line 40 can be used to transmit the intermediate frequency signal IF-, and the third microstrip line 50 can be used to transmit the intermediate frequency signal IF+. In other words, the middle common terminal of the two transistors can serve as the output or input terminal of the radio frequency signal RF, and the left and right electrodes of the two transistors can serve as the input or output terminal of the intermediate frequency signal IF.

[0072] Alternatively, referring to Figure 6 , the first microstrip line 30 can be used to transmit the intermediate frequency signal IF, the second microstrip line 40 can be used to transmit the radio frequency signal RF-, and the third microstrip line 50 can be used to transmit the radio frequency signal RF+. In other words, the common terminal between the two transistors can serve as the output or input of the intermediate frequency signal IF, while the left and right electrodes of the two transistors can serve as the input or output of the radio frequency signal RF.

[0073] 5 , the groove line 20 , the gate G1 of the first transistor 101 , and the gate G2 of the second transistor 102 may be located in the same layer and made of the same metal material, thereby effectively simplifying the mixer fabrication process and improving the mixer fabrication efficiency.

[0074] It is understood that the microstrip line may include a strip conductor located on top of a dielectric substrate and a ground plane located below the dielectric substrate. In the embodiment of the present application, the strip conductor of the first microstrip line 30, the strip conductor of the second microstrip line 40, the strip conductor of the second microstrip line 40, the first and second electrodes of the first transistor 101, and the first and second electrodes of the second transistor 102 may all be located on the same layer and may be made of the same metal material.

[0075] For example, referring to Figures 4 and 5 , the slot line 20, the strip conductors of each microstrip line, and the electrodes of each transistor in the core circuit 10 can all be located on the same layer and made of the same metal material. This effectively simplifies the mixer fabrication process and improves mixer fabrication efficiency.

[0076] As a first optional implementation, as shown in FIG3 , the mixer may further include a fourth microstrip line 60. The fourth microstrip line 60 may be connected to the slotline 20 and configured to transmit a local oscillator signal to the slotline 20. Specifically, one end of the slotline 20 is connected to the fourth microstrip line 60, and the other end is connected to the core circuit 10. The local oscillator signal transmitted by the fourth microstrip line 60 may be a single-ended signal. After being fed into the slotline 20, this single-ended signal may be converted into a differential signal. The slotline 20 may then feed the differential local oscillator signal into the core circuit 10.

[0077] Based on the above analysis and FIG3 , it can be seen that the transmission mode of the local oscillator signal can be converted from the microstrip line main transmission mode to the slot line main transmission mode, thereby realizing the change of the electromagnetic field transmission mode.

[0078] As a second optional implementation, referring to FIG5 , slotline 20 can be directly connected to a local oscillator port (not shown) and configured to receive a local oscillator signal outputted by the local oscillator port. The local oscillator signal outputted by the local oscillator port is a differential signal. As shown in FIG5 , the differential signal includes a LO+ signal and a LO- signal, and the LO+ and LO- signals have opposite phases.

[0079] By directly feeding in the differential local oscillator signal, there is no need to transmit the local oscillator signal from the microstrip line to the slot line and convert the signal transmission mode, which can effectively simplify the structure of the mixer.

[0080] Based on the two aforementioned implementations, it can be seen that in the embodiment of the present application, the two sides of the slot line 20 are connected to the gates of the two transistors, which can achieve differential feeding of the local oscillator signal, that is, the local oscillator signal fed into the core circuit 10 is a differential signal. This can provide common-mode rejection. Moreover, even if the local oscillator signal leaks to other signal ports of the mixer (such as the RF signal port), it can be ensured that the phase of the leaked local oscillator signal is opposite and the energy is offset, thereby effectively improving the local oscillator rejection.

[0081] As shown in FIG6 , the mixer may further include: at least one of a first frequency selection circuit 70, a second frequency selection circuit 80, a third frequency selection circuit 90, and a fourth frequency selection circuit 100. For example, the mixer shown in FIG6 includes the first frequency selection circuit 70, the second frequency selection circuit 80, the third frequency selection circuit 90, and the fourth frequency selection circuit 100.

[0082] The first frequency selection circuit 70 is connected to the end of the slot line 20 away from the core circuit 10. If the mixer further includes a fourth microstrip line 60, the first frequency selection circuit 70 can be connected to the slot line 20 via the fourth microstrip line 60. The second frequency selection circuit 80 is connected to the end of the first microstrip line 30 away from the core circuit 10, the third frequency selection circuit 90 is connected to the end of the second microstrip line 40 away from the core circuit 10, and the fourth frequency selection circuit 100 is connected to the end of the third microstrip line 50 away from the core circuit 10.

[0083] It is understood that a frequency selection circuit may also be referred to as a frequency selection network, frequency selection circuit, or matching network, and is used to achieve signal matching. For example, referring to FIG6 , each of the first frequency selection circuit 70, the second frequency selection circuit 80, the third frequency selection circuit 90, and the fourth frequency selection circuit 100 may include at least one filter. Of course, the frequency selection circuit may also include other signal processing components, which is not limited in the present embodiment.

[0084] It can also be understood that the first frequency selection circuit 70 connected to the slot line 20 can achieve matching of the local oscillator signal and open circuiting of the first, second, and third signals. The second frequency selection circuit 80 connected to the first microstrip line 30 can achieve matching of the first signal, open circuiting of the local oscillator signal, and short circuiting of the second and third signals. The third frequency selection circuit 90 connected to the second microstrip line 40 and the fourth frequency selection circuit 100 connected to the third microstrip line 50 can achieve matching of the second and third signals, open circuiting of the local oscillator signal, and short circuiting of the first signal.

[0085] In the embodiments of the present application, since the local oscillator signal is isolated from the transmission mode of the first signal, and from the transmission modes of the second and third signals, the complexity of matching the signal ports of the mixer can be effectively reduced, eliminating the need for high-suppression frequency selection circuits for each signal port. This effectively reduces the structural complexity and area of ​​each frequency selection circuit, thereby saving chip area and cost of the mixer. For example, compared to using microstrip lines to transmit the local oscillator signal, the first signal, the second signal, and the third signal, the mixer provided in the embodiments of the present application can save approximately 30% in both area and cost.

[0086] In summary, an embodiment of the present application provides a mixer that can transmit a local oscillator signal via a slot line and transmit a first signal, a second signal, and a third signal via a microstrip line. This ensures that the transmission mode of the local oscillator signal is different from the transmission mode of the first signal, and different from the transmission modes of the second and third signals. That is, the transmission mode of the local oscillator signal can be isolated from that of the first signal, and from the transmission modes of the second and third signals. Because the local oscillator signal is isolated from the electromagnetic field signal transmission mode of other signals, leakage of the local oscillator signal at other signal ports can be effectively reduced, thereby effectively improving the performance of the mixer.

[0087] Furthermore, the mixer can use FETs as nonlinear elements, effectively improving the mixer's frequency conversion efficiency and linearity. Furthermore, by achieving mode isolation between the local oscillator signal and other signals, the structural complexity of the mixer's frequency selection circuitry can be effectively reduced, thereby reducing the mixer's area and cost.

[0088] It is understood that because the mixers provided in the embodiments of the present application can effectively suppress local oscillator leakage in the core region (theoretically achieving 100% bandwidth local oscillator suppression at both RF and IF ports), they can be applied to the design and development of multi-band broadband devices. For example, they can be applied to the design of microwave UHF broadband circuits to ensure high microwave UHF radiation reception efficiency and good mode isolation.

[0089] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and "a plurality" means two or more.

[0090] In this application, the term "and / or" simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0091] The above are merely optional embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A mixer, characterized in that: The mixer comprises: a core circuit, a slot line, a first microstrip line, a second microstrip line and a third microstrip line; Wherein, the slot line, the first microstrip line, the second microstrip line and the third microstrip line are all connected to the core circuit; The slot line is used to transmit a local oscillator signal to the core circuit, the first microstrip line is used to transmit a first signal of a first frequency, the second microstrip line is used to transmit a second signal of a second frequency, and the third microstrip line is used to transmit a third signal of the second frequency, the second frequency is different from the first frequency, and the third signal is opposite in phase to the second signal; The core circuit is used to achieve frequency conversion between the first frequency and the second frequency based on the local oscillator signal.

2. The mixer according to claim 1, characterized in that The core circuit comprises: a first transistor and a second transistor, wherein a first electrode of the first transistor is connected to a first electrode of the second transistor; One side of the groove line is connected to the gate of the first transistor, and the other side of the groove line is connected to the gate of the second transistor; The first microstrip line is connected to a first electrode of the first transistor, the second microstrip line is connected to a second electrode of the first transistor, and the third microstrip line is connected to a second electrode of the second transistor.

3. The mixer according to claim 2, characterized in that The first transistor and the second transistor are both field effect transistors.

4. The mixer according to claim 2 or 3, characterized in that: The groove line, the gate of the first transistor, and the gate of the second transistor are located in the same layer.

5. The mixer according to any one of claims 2 to 4, characterized in that: The strip conductor of the first microstrip line, the strip conductor of the second microstrip line, the strip conductor of the third microstrip line, the first electrode and the second electrode of the first transistor, and the first electrode and the second electrode of the second transistor are all located in the same layer.

6. The mixer according to any one of claims 1 to 5, characterized in that: The mixer further includes: a fourth microstrip line; The fourth microstrip line is connected to the slot line and is used to transmit a local oscillator signal to the slot line.

7. The mixer according to any one of claims 1 to 5, characterized in that: The slot line is connected to the local oscillator port and is used to receive a local oscillator signal output by the local oscillator port. The local oscillator signal output by the local oscillator port is a differential signal.

8. The mixer according to any one of claims 1 to 7, characterized in that: The first signal is a radio frequency signal, and the second signal and the third signal are both intermediate frequency signals; Alternatively, the first signal is an intermediate frequency signal, and the second signal and the third signal are both radio frequency signals.

9. The mixer according to any one of claims 1 to 8, characterized in that: The first microstrip line is used to transmit the first signal to the core circuit, the second microstrip line is used to transmit the second signal output by the core circuit, and the third microstrip line is used to transmit the third signal output by the core circuit; Alternatively, the first microstrip line is used to transmit the first signal output by the core circuit, the second microstrip line is used to transmit the second signal to the core circuit, and the third microstrip line is used to transmit the third signal to the core circuit.

10. The mixer according to any one of claims 1 to 9, characterized in that: The mixer further includes: at least one of a first frequency selection circuit, a second frequency selection circuit, a third frequency selection circuit, and a fourth frequency selection circuit; The first frequency selection circuit is connected to the slot line, the second frequency selection circuit is connected to the first microstrip line, the third frequency selection circuit is connected to the second microstrip line, and the fourth frequency selection circuit is connected to the third microstrip line.

11. A signal transmission device, characterized in that: The signal transmission device comprises: an antenna, and a mixer as claimed in any one of claims 1 to 10; The mixer is used to perform frequency conversion on the signal received by the antenna, and / or the mixer is used to convert the signal after frequency conversion transmitted to the antenna.

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