A passive double balanced mixer

Abstract

The application relates to a passive double-balance frequency mixer. The passive double-balance frequency mixer comprises a local oscillator balun, a local oscillator coupling line, a diode ring, a radio frequency balun and an intermediate frequency lead-out circuit. The local oscillator balun and the radio frequency balun are both three-layer metal layer balun structures, efficient coupling of differential signals is realized by means of flowing single-end signals from a center feed-in point of the third layer metal structure of the balun structure into the vertically-overlapped microstrip line, and the amplitude and phase consistency of the differential signals is further improved through the local oscillator coupling line of the three-layer metal structure. The application enhances the isolation performance of the passive double-balance frequency mixer, realizes lower frequency conversion loss and high isolation in a super wideband range, and improves the frequency mixing efficiency and signal integrity of the passive double-balance frequency mixer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radio frequency microwave integrated circuits, and in particular to a passive double-balanced mixer. BACKGROUND

[0002] In the military fields of radar, electronic countermeasures, etc., with the continuous increase of high-power transmitting and jamming equipment, wideband transceiver systems have become important military equipment. The mixer is one of the core devices of the transceiver system, and its working principle is to produce combined frequency components through the "multiplier" effect of a nonlinear device, to screen out useful frequency components and suppress spurious frequency components, and to realize the frequency spectrum shift of the input signal. The passive double-balanced mixer has become the preferred solution for current mixer design due to its characteristics of no DC bias and simple and convenient use.

[0003] Currently, in the basic architecture of the passive double-balanced mixer, the local oscillator signal and the radio frequency signal are converted into two differential signals through the local oscillator balun and the radio frequency balun respectively, and are fed into a diode ring for mixing. The mixed intermediate frequency signal is led out through the center of the local oscillator balun or the radio frequency balun.

[0004] For the related technology in the above, the local oscillator balun and the radio frequency balun both adopt the mode of feeding in the local oscillator signal or the radio frequency signal from the end point of the metal layer, and the local oscillator balun and the radio frequency balun are both double-layer metal side-by-side structures. This design limits the effective coupling of the local oscillator signal or the radio frequency signal inside the balun, and because the double-layer metal balun structure layout is difficult to achieve good symmetry, the amplitude and phase consistency of the differential signal is difficult to effectively maintain when the local oscillator signal and the radio frequency signal are converted into differential signals, thereby resulting in low isolation performance of the passive double-balanced mixer. SUMMARY

[0005] The passive double-balanced mixer provided by the present application adopts the following technical solution:

[0006] A passive double-balanced mixer, comprising: a local oscillator balun, a local oscillator coupling line, a diode ring, a radio frequency balun, and an intermediate frequency leading-out circuit.

[0007] The local oscillator balun has a local oscillator balun comprehensive port, a local oscillator balun center ground port, a first local oscillator balun output port, a second local oscillator balun output port, and a first local oscillator balun metal layer, a second local oscillator balun metal layer and a third local oscillator balun metal layer arranged in sequence; the third local oscillator balun metal layer is configured with a local oscillator balun center feed-in point, and a first local oscillator balun microstrip line and a second local oscillator balun microstrip line symmetrically arranged with respect to the local oscillator balun center feed-in point, the local oscillator balun center feed-in point is connected to the local oscillator balun comprehensive port; the second local oscillator balun metal layer is configured with a local oscillator balun center intersection point and a third local oscillator balun microstrip line and a fourth local oscillator balun microstrip line symmetrically arranged with respect to the local oscillator balun center intersection point, the local oscillator balun center intersection point is connected to the local oscillator balun center ground port, the second local oscillator balun microstrip line and the third local oscillator balun microstrip line are vertically overlapped, and the first local oscillator balun microstrip line and the fourth local oscillator balun microstrip line are vertically overlapped; the first local oscillator balun metal layer is connected with the first local oscillator balun microstrip line, the second local oscillator balun microstrip line, the third local oscillator balun microstrip line and the fourth local oscillator balun microstrip line, and the first local oscillator balun metal layer is also connected to the first local oscillator balun output port, the second local oscillator balun output port and the ground; wherein the local oscillator signal flows into the local oscillator balun from the local oscillator balun center feed-in point, and is coupled to form a first differential local oscillator signal component and a second differential local oscillator signal component through the first local oscillator balun microstrip line, the second local oscillator balun microstrip line, the third local oscillator balun microstrip line and the fourth local oscillator balun microstrip line, the first differential local oscillator signal component flows out from the first local oscillator balun output port, and the second differential local oscillator signal component flows out from the second local oscillator balun output port.

[0008] By adopting the above scheme, the amplitude and phase consistency of the differential signal is significantly improved in the ultra-wideband range, ensuring that the local oscillator signal is effectively converted into a high-quality differential signal, thereby improving the isolation and spurious suppression performance of the passive double-balanced mixer. In addition, the above scheme also provides stable and efficient mixing performance for the passive double-balanced mixer, and has lower frequency conversion loss characteristics.

[0009] Optionally, the first local oscillator balun metal layer is connected with the first local oscillator balun microstrip line, the second local oscillator balun microstrip line, the third local oscillator balun microstrip line and the fourth local oscillator balun microstrip line; wherein the first end of the first local oscillator balun microstrip line is connected to the local oscillator balun center feed-in point, the second end of the first local oscillator balun microstrip line is connected to the first local oscillator balun metal layer and connected to the second local oscillator balun output port through the first local oscillator balun metal layer; the first end of the second local oscillator balun microstrip line is connected to the local oscillator balun center feed-in point, the second end of the second local oscillator balun microstrip line is connected to the first local oscillator balun metal layer and grounded through the first local oscillator balun metal layer; the first end of the third local oscillator balun microstrip line is connected to the local oscillator balun center intersection point, the second end of the third local oscillator balun microstrip line is connected to the first local oscillator balun metal layer and connected to the first local oscillator balun output port through the first local oscillator balun metal layer; the first end of the fourth local oscillator balun microstrip line is connected to the local oscillator balun center intersection point, the second end of the fourth local oscillator balun microstrip line is connected to the first local oscillator balun metal layer and grounded through the first local oscillator balun metal layer.

[0010] By adopting the above scheme, the parasitic effects in the process of mutual connection of the local oscillator balun metal layers and in the process of grounding of the local oscillator balun metal layers are reduced, the amplitude and phase consistency of the local oscillator balun is ensured, and thus the isolation and spurious suppression performance of the passive double balanced mixer are further improved.

[0011] Optionally, the second end of the first local oscillator balun microstrip line, the second end of the second local oscillator balun microstrip line, the second end of the third local oscillator balun microstrip line and the second end of the fourth local oscillator balun microstrip line are connected to the first local oscillator balun metal layer through the via hole.

[0012] By adopting the above scheme, the parasitic effects in the process of mutual connection of the local oscillator balun metal layers are reduced.

[0013] Optionally, the radio frequency balun comprises a radio frequency balun comprehensive port, a radio frequency balun center ground port, a first radio frequency balun output port, a second radio frequency balun output port, and a first radio frequency balun metal layer, a second radio frequency balun metal layer and a third radio frequency balun metal layer which are sequentially stacked; the third radio frequency balun metal layer is configured with a radio frequency balun center feed-in point, a first radio frequency balun microstrip line and a second radio frequency balun microstrip line which are symmetrically arranged with respect to the radio frequency balun center feed-in point, the radio frequency balun center feed-in point is connected to the radio frequency balun comprehensive port; the second radio frequency balun metal layer is configured with a radio frequency balun center intersection point, a third radio frequency balun microstrip line and a fourth radio frequency balun microstrip line which are symmetrically arranged with respect to the radio frequency balun center intersection point, the radio frequency balun center intersection point is connected to the radio frequency balun center ground port, the second radio frequency balun microstrip line and the third radio frequency balun microstrip line are vertically overlapped, and the first radio frequency balun microstrip line and the fourth radio frequency balun microstrip line are vertically overlapped; the first radio frequency balun metal layer is connected to the first radio frequency balun microstrip line, the second radio frequency balun microstrip line, the third radio frequency balun microstrip line and the fourth radio frequency balun microstrip line, and the first radio frequency balun metal layer is also connected to the first radio frequency balun output port, the second radio frequency balun output port and a ground terminal; wherein the radio frequency signal flows into the radio frequency balun from the radio frequency balun center feed-in point, and is coupled to form a first differential radio frequency signal component and a second differential radio frequency signal component through the first radio frequency balun microstrip line, the second radio frequency balun microstrip line, the third radio frequency balun microstrip line and the fourth radio frequency balun microstrip line, the first differential radio frequency signal component flows out from the first radio frequency balun output port, and the second differential radio frequency signal component flows out from the second radio frequency balun output port.

[0014] By adopting the above scheme, the amplitude and phase inconsistency of the radio frequency signal in the transmission process is effectively reduced, and it is ensured that the radio frequency signal can be effectively converted into a high-quality differential signal in a wideband range. In addition, the up-down overlapping radio frequency balun structure reduces the chip area, which is beneficial to the miniaturization and low cost of the circuit.

[0015] Optionally, the first radio frequency balun metal layer is connected with the first radio frequency balun microstrip line, the second radio frequency balun microstrip line, the third radio frequency balun microstrip line and the fourth radio frequency balun microstrip line; wherein the first end of the first radio frequency balun microstrip line is connected to the radio frequency balun center feeding point, and the second end of the first radio frequency balun microstrip line is connected to the first radio frequency balun metal layer and connected to the second radio frequency balun output port through the first radio frequency balun metal layer; the first end of the second radio frequency balun microstrip line is connected to the radio frequency balun center feeding point, and the second end of the second radio frequency balun microstrip line is connected to the first radio frequency balun metal layer and grounded through the first radio frequency balun metal layer; the first end of the third radio frequency balun microstrip line is connected to the radio frequency balun center intersection point, and the second end of the third radio frequency balun microstrip line is connected to the first radio frequency balun metal layer and connected to the first radio frequency balun output port through the first radio frequency balun metal layer; the first end of the fourth radio frequency balun microstrip line is connected to the radio frequency balun center intersection point, and the second end of the fourth radio frequency balun microstrip line is connected to the first radio frequency balun metal layer and grounded through the first radio frequency balun metal layer.

[0016] By using the above scheme, the parasitic effects in the process of mutual connection of the radio frequency balun metal layers and in the process of grounding of the radio frequency balun metal layers are reduced, the amplitude and phase consistency of the radio frequency balun is ensured, and thus the isolation and spurious suppression performance of the passive double balanced mixer are further improved.

[0017] Optionally, the second end of the first radio frequency balun microstrip line, the second end of the second radio frequency balun microstrip line, the second end of the third radio frequency balun microstrip line and the second end of the fourth radio frequency balun microstrip line are connected to the first radio frequency balun metal layer through vias.

[0018] By using the above scheme, the parasitic effects in the process of mutual connection of the radio frequency balun metal layers are reduced.

[0019] Optionally, the local oscillation coupling line comprises a first local oscillation coupling line input port, a second local oscillation coupling line input port, a local oscillation coupling line center ground port, a first local oscillation coupling line output port, a second local oscillation coupling line output port, and a first local oscillation coupling metal layer, a second local oscillation coupling metal layer and a third local oscillation coupling metal layer which are sequentially stacked; wherein the second local oscillation coupling metal layer is configured with a first local oscillation coupling line center intersection and a first local oscillation coupling microstrip line and a second local oscillation coupling microstrip line which are symmetrically arranged with respect to the first local oscillation coupling line center intersection, the first local oscillation coupling line center intersection is connected to the local oscillation coupling line center ground port, the third local oscillation coupling metal layer is configured with a second local oscillation coupling line center intersection and a third local oscillation coupling microstrip line and a fourth local oscillation coupling microstrip line which are symmetrically arranged with respect to the second local oscillation coupling line center intersection, the second local oscillation coupling line center intersection is connected to the intermediate frequency lead-out circuit, the first local oscillation coupling microstrip line and the third local oscillation coupling microstrip line are vertically overlapped, and the second local oscillation coupling microstrip line and the fourth local oscillation coupling microstrip line are vertically overlapped; the first local oscillation coupling metal layer is connected to the first local oscillation coupling microstrip line, the second local oscillation coupling microstrip line, the third local oscillation coupling microstrip line and the fourth local oscillation coupling microstrip line, and the first local oscillation coupling metal layer is also connected to the first local oscillation coupling line output port, the second local oscillation coupling line output port and the local oscillation coupling line center ground port; wherein the first differential local oscillation signal component flows into the local oscillation coupling line from the first local oscillation coupling line input port, the second differential local oscillation signal component flows into the local oscillation coupling line from the second local oscillation coupling line input port, is coupled through the first local oscillation coupling microstrip line, the second local oscillation coupling microstrip line, the third local oscillation coupling microstrip line and the fourth local oscillation coupling microstrip line, and the first differential local oscillation signal component flows out from the first local oscillation coupling line output port, and the second differential local oscillation signal component flows out from the second local oscillation coupling line output port.

[0020] By adopting the above technical solution, the amplitude and phase consistency of the local oscillation differential signal is further optimized, and the transmission quality of the local oscillation differential signal is ensured. In addition, the up-and-down overlapping local oscillation coupling line structure reduces the chip area, which is beneficial to the miniaturization and low cost of the circuit.

[0021] Optionally, the first local oscillator coupling metal layer is connected with the first local oscillator coupling microstrip line, the second local oscillator coupling microstrip line, the third local oscillator coupling microstrip line and the fourth local oscillator coupling microstrip line; wherein the first end of the first local oscillator coupling microstrip line is connected to the first local oscillator coupling line input port, the second end of the first local oscillator coupling microstrip line is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line center intersection through the first local oscillator coupling metal layer; the first end of the second local oscillator coupling microstrip line is connected to the second local oscillator coupling line input port, the second end of the second local oscillator coupling microstrip line is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line center intersection through the first local oscillator coupling metal layer; the first end of the third local oscillator coupling microstrip line is connected to the second local oscillator coupling line center intersection, the second end of the third local oscillator coupling microstrip line is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line output port through the first local oscillator coupling metal layer; the first end of the fourth local oscillator coupling microstrip line is connected to the second local oscillator coupling line center intersection, the second end of the fourth local oscillator coupling microstrip line is connected to the first local oscillator coupling metal layer and connected to the second local oscillator coupling line output port through the first local oscillator coupling metal layer.

[0022] By adopting the technical scheme, effective connection between local oscillator coupling metal layers and reasonable grounding are realized, parasitic effects in the process of mutual connection of local oscillator coupling metal layers and grounding of local oscillator coupling metal layers are reduced, and the amplitude and phase consistency of local oscillator differential signals is further improved, so that the isolation and spurious suppression performance of the passive double balanced mixer are improved.

[0023] Optionally, the diode ring includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, the cathode of the first diode D1 is connected to the cathode of the second diode D2 and forms a first diode ring port, the anode of the second diode D2 is connected to the cathode of the third diode D3 and forms a second diode ring port, the anode of the third diode D3 is connected to the anode of the fourth diode D4 and forms a third diode ring port, and the cathode of the fourth diode D4 is connected to the anode of the first diode D1 and forms a fourth diode ring port; the first diode ring port is connected to the first local oscillator coupling line output port, the second diode ring port is connected to the second radio frequency balun output port, the third diode ring port is connected to the second local oscillator coupling line output port, and the fourth diode ring port is connected to the first radio frequency balun output port.

[0024] By adopting the technical scheme, effective mixing of the local oscillator signal and the radio frequency signal is realized, the mixing efficiency and the isolation of the passive double-balance mixer are improved, meanwhile, the interference of the spurious signal is reduced, and the overall performance and stability of the radio frequency system are improved.

[0025] Optionally, the intermediate frequency leading circuit comprises an intermediate frequency metal layer and an intermediate frequency port, the intermediate frequency signal flows into or out of the intermediate frequency port, wherein the intermediate frequency microstrip line is constructed in the intermediate frequency metal layer, a first end of the intermediate frequency microstrip line is connected to the second local oscillator coupling line center intersection, and a second end of the intermediate frequency microstrip line is connected to the intermediate frequency port.

[0026] By adopting the technical scheme, a clear path is provided for the intermediate frequency signal, effective leading of the intermediate frequency signal is realized, and the isolation of the intermediate frequency signal and the local oscillator signal is improved. Through the above, the present application has at least one of the following beneficial technical effects:

[0027] The amplitude and phase consistency of the differential signal is significantly improved in the ultra-wideband range, the local oscillator signal and the radio frequency signal are effectively converted into high-quality differential signals, thereby improving the isolation and spurious suppression performance of the passive double-balance mixer, in addition, the passive double-balance mixer is provided with stable and efficient mixing performance, and has a low frequency conversion loss characteristic;

[0028] The local oscillator / radio frequency balun metal layer is effectively connected and reasonably grounded between the local oscillator / radio frequency balun metal layer, the parasitic effect in the process of mutual connection of the local oscillator / radio frequency metal layer and grounding of the local oscillator / radio frequency metal layer is reduced, the amplitude and phase consistency of the local oscillator / radio frequency balun is ensured, thereby further improving the isolation and spurious suppression performance of the passive double-balance mixer. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structural schematic diagram of a passive double-balance mixer of related technology;

[0030] Figure 2 is a planar structural schematic diagram of a passive double-balance mixer of an embodiment of the present application;

[0031] Figure 3 is a planar structural schematic diagram of the local oscillator balun in Figure 2 ;

[0032] Figure 4 is a three-dimensional structural schematic diagram of the local oscillator balun in Figure 2 ;

[0033] Figure 5 is a planar structural schematic diagram of the radio frequency balun in Figure 2 ;

[0034] Figure 6 is a three-dimensional structural schematic diagram of the radio frequency balun in Figure 2A planar structure schematic diagram of the local oscillator coupling line and the intermediate frequency leading circuit in the device;

[0035] Figure 7 is Figure 2 A planar structure schematic diagram of the diode ring in the device;

[0036] Figure 8 is a measured result diagram of the down-conversion loss of the passive double-balanced mixer in the embodiment of the present application;

[0037] Figure 9 is a measured result diagram of the isolation of the local oscillator signal and the radio frequency signal of the passive double-balanced mixer in the embodiment of the present application;

[0038] Figure 10 is a measured result diagram of the isolation of the local oscillator signal and the intermediate frequency signal of the passive double-balanced mixer in the embodiment of the present application;

[0039] Figure 11 is a measured result diagram of the isolation of the radio frequency signal and the intermediate frequency signal of the passive double-balanced mixer in the embodiment of the present application.

[0040] Legend: 110, conventional local oscillator balun; 111, first conventional local oscillator balun microstrip line; 112, second conventional local oscillator balun microstrip line; 113, third conventional local oscillator balun microstrip line; 120, conventional radio frequency balun; 121, first conventional radio frequency balun microstrip line; 122, second conventional radio frequency balun microstrip line; 123, third conventional radio frequency balun microstrip line; 130, conventional diode ring; 140, conventional intermediate frequency extraction circuit; 210, local oscillator balun; 211, local oscillator balun composite port; 212, local oscillator balun center feed point; 213a, first local oscillator balun microstrip line; 213b, second local oscillator balun microstrip line; 213c, third local oscillator balun microstrip line; 213d, fourth local oscillator balun microstrip line; 214, local oscillator balun center cross point; 215, local oscillator balun center ground port; 216, first local oscillator balun output port; 217, second local oscillator balun output port; 220, radio frequency balun; 221, radio frequency balun composite port; 222, radio frequency balun center feed point; 223a, first radio frequency balun microstrip line; 223b, second radio frequency balun microstrip line; 223c, third radio frequency balun microstrip line; 223d, fourth radio frequency balun microstrip line; 224, radio frequency balun center cross point; 225, radio frequency balun center ground port; 226, first radio frequency balun output port; 227, second radio frequency balun output port; 230, local oscillator coupling line; 231, first local oscillator coupling line input port; 232, second local oscillator coupling line input port; 233, first local oscillator coupling line center cross point; 234a, first local oscillator coupling microstrip line; 234b, second local oscillator coupling microstrip line; 234c, third local oscillator coupling microstrip line; 234d, fourth local oscillator coupling microstrip line; 235, local oscillator coupling line center ground port; 236, first local oscillator coupling line output port; 237, second local oscillator coupling line output port; 238, second local oscillator coupling line center cross point; 240, diode ring; 241, first diode ring port; 242, second diode ring port; 243, third diode ring port; 244, fourth diode ring port; 250, intermediate frequency extraction circuit; 251, intermediate frequency microstrip line; 252, intermediate frequency port. DETAILED DESCRIPTION

[0041] The following detailed description is made in connection with the accompanying drawings. Figures 1-11 The application is further described in detail.

[0042] In order to achieve efficient conversion of single-ended signals to differential signals, and to generate high-quality intermediate frequency signals in the mixing process, Figure 1 A passive double-balanced mixer of the related art is shown.

[0043] As Figure 1As shown, the passive double balanced mixer comprises a conventional local oscillator balun 110, a conventional radio frequency balun 120, a conventional diode ring 130 and a conventional intermediate frequency lead-out circuit 140 connected with the conventional local oscillator balun in sequence. The conventional local oscillator balun 110 has a first conventional local oscillator balun metal layer and a second conventional local oscillator balun metal layer, and the first conventional local oscillator balun metal layer is configured with a first conventional local oscillator balun microstrip line 111, and the second conventional local oscillator balun metal layer is configured with a second conventional local oscillator balun microstrip line 112 and a third conventional local oscillator balun microstrip line 113; the conventional radio frequency balun 120 has a first conventional radio frequency balun metal layer and a second conventional radio frequency balun metal layer, and the first conventional radio frequency balun metal layer is configured with a first conventional radio frequency balun microstrip line 121, and the second conventional radio frequency balun metal layer is configured with a second conventional radio frequency balun microstrip line 122 and a third conventional radio frequency balun microstrip line 123; the conventional diode ring 130 is formed by four diodes into a closed ring structure; and the conventional intermediate frequency lead-out circuit 140 has a conventional intermediate frequency metal layer and a conventional intermediate frequency port.

[0044] The working principle of the passive double balanced mixer is as follows: a local oscillator signal (LO) flows into the first conventional local oscillator balun microstrip line 111 from one end of the first conventional local oscillator balun metal layer, and is coupled to the second conventional local oscillator balun microstrip line 112 and the third conventional local oscillator balun microstrip line 113 in the second conventional local oscillator balun metal layer to be converted into a differential local oscillator signal. The differential local oscillator signal is then transmitted by the second conventional local oscillator balun microstrip line 112 and the third conventional local oscillator balun microstrip line 113 to the conventional diode ring 130, a radio frequency signal (RF) flows into the first conventional radio frequency balun microstrip line 121 from one end of the first conventional radio frequency balun metal layer, and is coupled to the second conventional radio frequency balun microstrip line 122 and the third conventional radio frequency balun microstrip line 123 in the second conventional radio frequency balun metal layer to be converted into a differential radio frequency signal, and the differential radio frequency signal is then transmitted by the second conventional radio frequency balun microstrip line 122 and the third conventional radio frequency balun microstrip line 123 to the conventional diode ring 130, the conventional diode ring 130 mixes the received differential local oscillator signal and differential radio frequency signal to generate an intermediate frequency signal (IF), and the mixed intermediate frequency signal is led out through the center of the conventional local oscillator balun 110.

[0045] However, the passive double balanced mixer in the prior art still has the following defects: the conventional local oscillator balun 110 and the conventional radio frequency balun 120 both adopt a mode of feeding in a local oscillator signal or a radio frequency signal from a metal layer end point, and the conventional local oscillator balun 110 and the conventional radio frequency balun 120 are both double-layer metal side-by-side structures. Such a design limits the effective coupling and transmission distance of the local oscillator signal or the radio frequency signal inside the balun, and due to the difficulty in achieving good symmetry of the double-layer metal balun structure layout, it is difficult to maintain amplitude and phase consistency during signal transmission, thereby resulting in low isolation performance of the passive double balanced mixer.

[0046] In view of the above related art, the embodiment of the present application discloses a passive double balanced mixer.

[0047] With reference to Figure 2 The passive double balanced mixer includes a local oscillator balun 210, a local oscillator coupling line 230, a diode ring 240, a radio frequency balun 220, and an intermediate frequency lead-out circuit 250. Among them, the local oscillator balun 210, the local oscillator coupling line 230, and the radio frequency balun 220 realize efficient signal coupling through their unique stacked metal layer structure and microstrip line layout. The diode ring 240 uses the nonlinear characteristic to mix the signal, and the intermediate frequency lead-out circuit 250 is responsible for leading out the mixed intermediate frequency signal, achieving the effect of reducing conversion loss and improving isolation in the ultra-wideband range. The local oscillator balun 210 and the radio frequency balun 220 convert single-ended signals into high-quality differential signals, the local oscillator coupling line 230 enhances signal transmission, the diode ring 240 realizes mixing, and the intermediate frequency lead-out circuit 250 ensures stable output of the intermediate frequency signal.

[0048] With reference to Figure 3 and Figure 4 The local oscillator balun 210 includes a local oscillator balun comprehensive port 211, a local oscillator balun center ground port 215, a first local oscillator balun output port 216, a second local oscillator balun output port 217, and a first local oscillator balun metal layer, a second local oscillator balun metal layer, and a third local oscillator balun metal layer arranged in sequence. The local oscillator balun comprehensive port 211 is used for inputting a local oscillator signal, and the local oscillator balun center ground port 215 plays a grounding role to ensure the stability of signal transmission. The first local oscillator balun output port 216 and the second local oscillator balun output port 217 are used for outputting differential local oscillator signals. The second local oscillator balun metal layer and the third local oscillator balun metal layer are arranged in sequence above the first local oscillator balun metal layer.

[0049] The third local oscillator balun metal layer is configured with a local oscillator balun center feed-in point 212 and a first local oscillator balun microstrip line 213a and a second local oscillator balun microstrip line 213b symmetrically arranged opposite the local oscillator balun center feed-in point 212, and the local oscillator balun center feed-in point 212 is connected to the local oscillator balun comprehensive port 211. The local oscillator balun center feed-in point 212 is the input node of the local oscillator signal, which ensures efficient transmission of the signal. The second local oscillator balun metal layer is configured with a local oscillator balun center intersection point 214 and a third local oscillator balun microstrip line 213c and a fourth local oscillator balun microstrip line 213d symmetrically arranged opposite the local oscillator balun center intersection point 214, and the local oscillator balun center intersection point 214 is connected to the local oscillator balun center ground port 215; the second local oscillator balun microstrip line 213b and the third local oscillator balun microstrip line 213c are vertically overlapped, and the first local oscillator balun microstrip line 213a and the fourth local oscillator balun microstrip line 213d are vertically overlapped. The local oscillator balun center intersection point 214 is the intersection point of the signal, which plays a role in signal distribution and grounding.

[0050] The first local oscillator balun metal layer is connected with the first local oscillator balun microstrip line 213a, the second local oscillator balun microstrip line 213b, the third local oscillator balun microstrip line 213c and the fourth local oscillator balun microstrip line 213d, wherein the first end of the first local oscillator balun microstrip line 213a is connected to the local oscillator balun center feed-in point 212, the second end of the first local oscillator balun microstrip line 213a is connected to the first local oscillator balun metal layer through a via, and the first local oscillator balun metal layer is connected to the second local oscillator balun output port 217; the first end of the second local oscillator balun microstrip line 213b is connected to the local oscillator balun center feed-in point 212, the second end of the second local oscillator balun microstrip line 213b is connected to the first local oscillator balun metal layer through a via, and the first local oscillator balun metal layer is grounded; the first end of the third local oscillator balun microstrip line 213c is connected to the local oscillator balun center intersection point 214, the second end of the third local oscillator balun microstrip line 213c is connected to the first local oscillator balun metal layer through a via, and the first local oscillator balun metal layer is connected to the first local oscillator balun output port 216; the first end of the fourth local oscillator balun microstrip line 213d is connected to the local oscillator balun center intersection point 214, the second end of the fourth local oscillator balun microstrip line 213d is connected to the first local oscillator balun metal layer through a via, and the first local oscillator balun metal layer is grounded. The via is a vertical conductive channel for connecting the microstrip lines between different metal layers.

[0051] The local oscillator signal flows into the local oscillator balun 210 from the local oscillator balun center feed-in point 212, and is coupled and transmitted through the first local oscillator balun microstrip line 213a, the second local oscillator balun microstrip line 213b, the third local oscillator balun microstrip line 213c and the fourth local oscillator balun microstrip line 213d. The second local oscillator balun microstrip line 213b and the third local oscillator balun microstrip line 213c are coupled to each other to form a first differential local oscillator signal component; the first local oscillator balun microstrip line 213a and the fourth local oscillator balun microstrip line 213d are coupled to each other to form a second differential local oscillator signal component; the first differential local oscillator signal component and the second differential local oscillator signal component form a differential local oscillator signal pair with equal amplitude and opposite phase, thereby forming a differential local oscillator signal. The first differential local oscillator signal component flows out from the first local oscillator balun output port 216, and the second differential local oscillator signal component flows out from the second local oscillator balun output port 217. This structure design enables efficient coupling of the local oscillator signal in the vertically overlapped microstrip lines, and improves the amplitude and phase consistency of the differential signal.

[0052] Referring to Figure 5 The radio frequency balun 220 includes a radio frequency balun comprehensive port 221, a radio frequency balun center ground port 225, a first radio frequency balun output port 226, a second radio frequency balun output port 227, and a first radio frequency balun metal layer, a second radio frequency balun metal layer and a third radio frequency balun metal layer arranged in sequence. The radio frequency balun 220 has basically the same structure as the local oscillator balun 210. The radio frequency balun comprehensive port 221 is used for inputting a radio frequency signal, and can also use a standard radio frequency interface such as an SMA interface. The radio frequency balun center ground port 225 serves as a ground to ensure the stability of radio frequency signal transmission. The first radio frequency balun output port 226 and the second radio frequency balun output port 227 are used for outputting differential radio frequency signals, and the connection with subsequent circuits needs to ensure accurate signal transmission. The first radio frequency balun metal layer is the basic layer of the radio frequency balun 220, and is made of similar metal materials and processes as the metal layer of the local oscillator balun 210. The second radio frequency balun metal layer and the third radio frequency balun metal layer are arranged in sequence above the first radio frequency balun metal layer and are separated from the first radio frequency balun metal layer by an insulating medium.

[0053] The third radio frequency balun metal layer is configured with a radio frequency balun center feed-in point 222 and a first radio frequency balun microstrip line 223a and a second radio frequency balun microstrip line 223b symmetrically arranged opposite the radio frequency balun center feed-in point 222, and the radio frequency balun center feed-in point 222 is connected to the radio frequency balun comprehensive port 221. The design of the radio frequency balun center feed-in point 222 is similar to that of the local oscillator balun center feed-in point 212, so as to ensure efficient input of the radio frequency signal. The second radio frequency balun metal layer is configured with a radio frequency balun center intersection point 224 and a third radio frequency balun microstrip line 223c and a fourth radio frequency balun microstrip line 223d symmetrically arranged opposite the radio frequency balun center intersection point 224, and the radio frequency balun center intersection point 224 is connected to the radio frequency balun center ground port 225; the second radio frequency balun microstrip line 223b and the third radio frequency balun microstrip line 223c are vertically overlapped, and the first radio frequency balun microstrip line 223a and the fourth radio frequency balun microstrip line 223d are vertically overlapped. The radio frequency balun center intersection point 224 has a similar function to the local oscillator balun center intersection point 214, and ensures the symmetry of the signal and the grounding effect.

[0054] The first radio frequency balun metal layer is connected with the first radio frequency balun microstrip line 223a, the second radio frequency balun microstrip line 223b, the third radio frequency balun microstrip line 223c and the fourth radio frequency balun microstrip line 223d, wherein the first end of the first radio frequency balun microstrip line 223a is connected to the radio frequency balun center feed-in point 222, the second end of the first radio frequency balun microstrip line 223a is connected to the first radio frequency balun metal layer through a via hole, and is connected to the second radio frequency balun output port 227 through the first radio frequency balun metal layer; the first end of the second radio frequency balun microstrip line 223b is connected to the radio frequency balun center feed-in point 222, the second end of the second radio frequency balun microstrip line 223b is connected to the first radio frequency balun metal layer through a via hole, and is grounded through the first radio frequency balun metal layer; the first end of the third radio frequency balun microstrip line 223c is connected to the radio frequency balun center intersection point 224, the second end of the third radio frequency balun microstrip line 223c is connected to the first radio frequency balun metal layer through a via hole, and is connected to the first radio frequency balun output port 226 through the first radio frequency balun metal layer; the first end of the fourth radio frequency balun microstrip line 223d is connected to the radio frequency balun center intersection point 224, and the second end of the fourth radio frequency balun microstrip line 223d is connected to the first radio frequency balun metal layer through a via hole, and is grounded through the first radio frequency balun metal layer.

[0055] The radio frequency signal flows into the radio frequency balun from the radio frequency balun center feed-in point 222, and is coupled and transmitted through the first radio frequency balun microstrip line 223a, the second radio frequency balun microstrip line 223b, the third radio frequency balun microstrip line 223c and the fourth radio frequency balun microstrip line 223d. The second radio frequency balun microstrip line 223b and the third radio frequency balun microstrip line 223c are coupled with each other to form a first differential radio frequency signal component; the first radio frequency balun microstrip line 223a and the fourth radio frequency balun microstrip line 223d are coupled with each other to form a second differential radio frequency signal component; the first differential radio frequency signal component and the second differential radio frequency signal component constitute a differential pair with equal amplitude and opposite phase, thereby generating a differential radio frequency signal. The first differential radio frequency signal component flows out from the first radio frequency balun output port 226, and the second differential radio frequency signal component flows out from the second radio frequency balun output port 227.

[0056] With reference to Figure 6 The local oscillator coupling line 230 includes a first local oscillator coupling line input port 231, a second local oscillator coupling line input port 232, a local oscillator coupling line center ground port 235, a first local oscillator coupling line output port 236, a second local oscillator coupling line output port 237, and a first local oscillator coupling metal layer, a second local oscillator coupling metal layer and a third local oscillator coupling metal layer arranged in sequence. The first local oscillator coupling metal layer is the basic layer of the local oscillator coupling line and is made of a metal material with good electrical conductivity. The second local oscillator coupling metal layer and the third local oscillator coupling metal layer are arranged in sequence above the first local oscillator coupling metal layer and are separated from the first local oscillator coupling metal layer by an insulating medium.

[0057] The first local oscillator coupling line center intersection point 233 and the first local oscillator coupling microstrip line 234a and the second local oscillator coupling microstrip line 234b symmetrically arranged with respect to the first local oscillator coupling line center intersection point 233 are constructed in the second local oscillator coupling metal layer, the first local oscillator coupling line center intersection point 233 is connected to the local oscillator coupling line center ground port 235, the second local oscillator coupling line center intersection point 238 and the third local oscillator coupling microstrip line 234c and the fourth local oscillator coupling microstrip line 234d symmetrically arranged with respect to the second local oscillator coupling line center intersection point 238 are constructed in the third local oscillator coupling metal layer, the second local oscillator coupling line center intersection point 238 is connected to the intermediate frequency lead-out circuit 250, the first local oscillator coupling microstrip line 234a and the third local oscillator coupling microstrip line 234c are vertically overlapped, and the second local oscillator coupling microstrip line 234b and the fourth local oscillator coupling microstrip line 234d are vertically overlapped. The first local oscillator coupling line center intersection point 233 and the second local oscillator coupling line center intersection point 238 respectively play the roles of signal distribution and connection.

[0058] The first local oscillator coupling metal layer is connected with the first local oscillator coupling microstrip line 234a, the second local oscillator coupling microstrip line 234b, the third local oscillator coupling microstrip line 234c and the fourth local oscillator coupling microstrip line 234d, realizing efficient coupling and transmission of the differential local oscillator signal. The first end of the first local oscillator coupling microstrip line 234a is connected to the first local oscillator coupling line input port 231, the second end of the first local oscillator coupling microstrip line 234a is connected to the first local oscillator coupling metal layer through a via, and the first local oscillator coupling metal layer is connected to the first local oscillator coupling line center intersection 233. The first end of the second local oscillator coupling microstrip line 234b is connected to the second local oscillator coupling line input port 232, the second end of the second local oscillator coupling microstrip line 234b is connected to the first local oscillator coupling metal layer through a via, and the first local oscillator coupling metal layer is connected to the first local oscillator coupling line center intersection 233. The first end of the third local oscillator coupling microstrip line 234c is connected to the second local oscillator coupling line center intersection 238, the second end of the third local oscillator coupling microstrip line 234c is connected to the first local oscillator coupling metal layer through a via, and the first local oscillator coupling metal layer is connected to the first local oscillator coupling line output port 236. The first end of the fourth local oscillator coupling microstrip line 234d is connected to the second local oscillator coupling line center intersection 238, the second end of the fourth local oscillator coupling microstrip line 234d is connected to the first local oscillator coupling metal layer through a via, and the first local oscillator coupling metal layer is connected to the second local oscillator coupling line output port 237. The first local oscillator coupling line input port 231 and the second local oscillator coupling line input port 232 are respectively used for inputting two components of the differential local oscillator signal. The first local oscillator coupling line center ground port 235 plays a grounding role, ensuring the stability of signal transmission. The first local oscillator coupling line output port 236 and the second local oscillator coupling line output port 237 are used for outputting the coupled differential local oscillator signal.

[0059] The first differential local oscillator signal component flows into the local oscillator coupling line 230 from the first local oscillator coupling line input port 231, and the second differential local oscillator signal component flows into the local oscillator coupling line 230 from the second local oscillator coupling line input port 232. The first local oscillator coupling microstrip line 234a and the third local oscillator coupling microstrip line 234c are coupled and transmitted to each other, and the first differential local oscillator signal component flows out from the first local oscillator coupling line output port 236. The second local oscillator coupling microstrip line 234b and the fourth local oscillator coupling microstrip line 234d are coupled and transmitted to each other, and the second differential local oscillator signal component flows out from the second local oscillator coupling line output port 237. This structure design enhances the transmission efficiency and coupling degree of the differential local oscillator signal, further improving the quality of the signal.

[0060] Referring to Figure 7The diode ring 240 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, all of which are high-performance Schottky diodes, having the advantages of fast switching speed and good non-linear characteristics. The cathode of the first diode D1 is connected to the cathode of the second diode D2 and forms a first diode ring port 241, the anode of the second diode D2 is connected to the cathode of the third diode D3 and forms a second diode ring port 242, the anode of the third diode D3 is connected to the anode of the fourth diode D4 and forms a third diode ring port 243, and the cathode of the fourth diode D4 is connected to the anode of the first diode D1 and forms a fourth diode ring port 244. The first diode ring port 241 is connected to the first local oscillator coupling line output port 236, the second diode ring port 242 is connected to the second radio frequency balun output port 227, the third diode ring port 243 is connected to the second local oscillator coupling line output port 237, and the fourth diode ring port 244 is connected to the first radio frequency balun output port 226. This connection allows the diode ring 240 to receive differential local oscillator signals and differential radio frequency signals from the local oscillator coupling line 230 and the radio frequency balun 220, and to mix the two signals using the non-linear characteristics of the diodes, thereby generating intermediate frequency signals. In addition, in the up-conversion operating mode, it can also operate in reverse, mixing the input differential local oscillator signals with the intermediate frequency signals, and flowing the up-converted differential radio frequency signals into the radio frequency balun 220.

[0061] The intermediate frequency lead-out circuit 250 receives the mixed intermediate frequency signals and outputs them to the intermediate frequency port 252 in the down-conversion operating mode, and in the up-conversion operating mode, it serves as an input channel for unmixed intermediate frequency signals, leading the unmixed intermediate frequency signals from the intermediate frequency port 252 into the local oscillator coupling line 230.

[0062] The intermediate frequency lead-out circuit 250 includes an intermediate frequency metal layer and the intermediate frequency port 252. The intermediate frequency metal layer is made of a metal material with good electrical conductivity, such as copper, and has an intermediate frequency microstrip line 251 constructed therein. The first end of the intermediate frequency microstrip line 251 is connected to the second local oscillator coupling line center intersection 238, and the second end of the intermediate frequency microstrip line 251 is connected to the intermediate frequency port 252. Intermediate frequency signals flow in or out of the intermediate frequency port 252. In the down-conversion operating mode, the intermediate frequency lead-out circuit 250 receives the mixed intermediate frequency signals and outputs them to the intermediate frequency port 252, and in the up-conversion operating mode, it serves as an input channel for unmixed intermediate frequency signals, leading the unmixed intermediate frequency signals from the intermediate frequency port 252 into the local oscillator coupling line 230.

[0063] In the down-conversion state, the local signal flows into the local balun 210 from the local balun composite port 211 through the local balun center feed-in point 212, and is coupled and transmitted through the first local coupling microstrip line 234a, the second local coupling microstrip line 234b, the third local coupling microstrip line 234c and the fourth local coupling microstrip line 234d. The second local balun microstrip line 213b and the third local balun microstrip line 213c are coupled with each other to form a first differential local signal component; the first local balun microstrip line 213a and the fourth local balun microstrip line 213d are coupled with each other to form a second differential local signal component; the first differential local signal component and the second differential local signal component constitute a differential pair of local signals with equal amplitude and opposite phase, thereby forming a differential local signal. The first differential local signal component flows out from the first local balun output port 216, and the second differential local signal component flows out from the second local balun output port 217; the first differential local signal component flows into the local coupling line 230 from the first local coupling line input port 231, and the second differential local signal component flows into the local coupling line 230 from the second local coupling line input port 232. The first local coupling microstrip line 234a and the third local coupling microstrip line 234c are coupled and transmitted with each other, and the first differential local signal component flows out from the first local coupling line output port 236; the second local coupling microstrip line 234b and the fourth local coupling microstrip line 234d are coupled and transmitted with each other, and the second differential local signal component flows out from the second local coupling line output port 237; the radio frequency signal flows into the radio frequency balun 220 from the radio frequency balun center feed-in point 222, and is coupled and transmitted through the first radio frequency balun microstrip line 223a, the second radio frequency balun microstrip line 223b, the third radio frequency balun microstrip line 223c and the fourth radio frequency balun microstrip line 223d. The second radio frequency balun microstrip line 223b and the third radio frequency balun microstrip line 223c are coupled with each other to form a first differential radio frequency signal component; the first radio frequency balun microstrip line 223a and the fourth radio frequency balun microstrip line 223d are coupled with each other to form a second differential radio frequency signal component; the first differential radio frequency signal component and the second differential radio frequency signal component constitute a differential pair with equal amplitude and opposite phase, thereby generating a differential radio frequency signal. The first differential radio frequency signal component flows out from the first radio frequency balun output port 226, and the second differential radio frequency signal component flows out from the second radio frequency balun output port 227;

[0064] Meanwhile, the first diode ring port 241 of the diode ring 240 flows in the first local oscillator differential signal component from the first local oscillator coupler output port 236, the second diode ring port 242 flows in the second radio frequency differential signal component from the second radio frequency balun output port 227, the third diode ring port 243 flows in the second local oscillator differential signal component from the second local oscillator coupler output port 237, and the fourth diode ring port 244 flows in the first radio frequency differential signal component from the first radio frequency balun output port 226. Finally, the first local oscillator differential signal component, the second local oscillator differential signal component, the first radio frequency differential signal component, and the second radio frequency differential signal component are nonlinearly mixed in the diode ring 240 to form a mixed intermediate frequency signal, which flows into the local oscillator coupler 230 through the first diode ring port 241 and the third diode ring port 243, converges at the second local oscillator coupler center intersection 238, flows into the first end of the intermediate frequency microstrip line 251, and is transmitted to the second end of the intermediate frequency microstrip line 251, and finally is output through the intermediate frequency port 252.

[0065] In the up-conversion state, the local signal flows into the local balun 210 from the local balun integrated port 211 through the local balun center feed-in point 212, is converted into the first local differential signal component and the second local differential signal component, and is transmitted to the diode ring 240 through the local coupling line 230. The process is basically the same as the above-mentioned down-conversion state. The first diode ring port 241 of the diode ring 240 flows in the first local differential signal component from the first local coupling line output port 236, and the third diode ring port 243 flows in the second local differential signal component from the second local coupling line output port 237. At the same time, the un-mixed intermediate frequency signal flows in from the intermediate frequency port 252, enters the local coupling line 230 through the second local coupling line center intersection point 238 via the intermediate frequency lead-out circuit 250, and enters the diode ring through the first diode ring port 241 and the third diode ring port 243 of the diode ring 240. Finally, the intermediate frequency signal and the first local differential signal component and the second local differential signal component are mixed in the diode ring 240 to generate the first differential radio frequency signal component and the second differential radio frequency signal component. The first differential radio frequency signal component flows into the radio frequency balun 220 from the fourth diode ring port 244 of the diode ring, and the second differential radio frequency signal component flows into the radio frequency balun 220 from the second diode ring port 242 of the diode ring. The first differential radio frequency signal is coupled with the second radio frequency balun microstrip line 223b through the third radio frequency balun microstrip line 223c, and the second differential radio frequency signal is coupled with the fourth radio frequency balun microstrip line 223d through the first radio frequency balun microstrip line 223a. The coupled first differential radio frequency signal component and the second differential radio frequency signal component form a radio frequency signal differential pair with equal amplitude and opposite phase, thereby forming a differential radio frequency signal. The differential radio frequency signal flows out from the radio frequency balun center feed-in point 222 through the radio frequency balun integrated port 221.

[0066] The passive double-balanced mixer can enhance the amplitude and phase consistency of the signal by fine-tuning the balun structure of the local balun 210 and the radio frequency balun 220, thereby improving the isolation of the passive double-balanced mixer. The following will be described in conjunction with specific cases.

[0067] Taking the local balun 210 as an example, the balun structure of the local balun 210 is initially designed to be completely symmetrical, in which the third local balun microstrip line 213c and the fourth local balun microstrip line 213d have the same odd-mode impedance and even-mode impedance. The local balun 210 is equivalent to a three-port network, and the amplitude imbalance of the local balun 210 can be expressed as follows:

[0068]

[0069] Wherein, S represents the scattering parameter of the network; S 21S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z 31 S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z 0e 0o S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z

[0070] The expression shows that when the coupling degree approaches the ideal value 1 (i.e. 0 dB), the amplitude imbalance of the LO balun 210 will approach 0 (infinitesimal). It is concluded that the maximum coupling degree potential upper limit that the balun structure of the LO balun 210 can achieve directly affects the amplitude consistency of the LO balun 210.

[0071] In order to further illustrate the quantitative relationship between the input impedance of the first LO balun output port 216 and the odd mode / even mode of the third LO balun microstrip line 213c, and the input impedance of the second LO balun output port 217 and the odd mode / even mode of the fourth LO balun microstrip line 213d, a more detailed analysis is made on the third LO balun microstrip line 213c and the fourth LO balun microstrip line 213d, which is expressed as follows:

[0072]

[0073] wherein, S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z L1 S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z L2 S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z

[0074] Through the above formula, the input impedance Z1 of the first LO balun output port 216 and the input impedance Z2 of the second LO balun output port 217 can be further derived, which is expressed as follows:

[0075]

[0076] wherein, 0e1 S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z 0o1 S represents the transmission coefficient of the LO balun composite port 211 to the first LO balun output port 216 when the LO balun composite port 211 is matched to the second LO balun output port 217; Z1 represents the input impedance of the first LO balun output port 216, Z2 represents the input impedance of the second LO balun output port 217, Z​0e2 Z 0o2 Z

[0077]

[0078] S 21 =-S 31 , and S 11 =0

[0079] i.e. the output amplitudes of the first local oscillator balun output port 216 and the second local oscillator balun output port 217 are equal, the output phases of the first local oscillator balun output port 216 and the second local oscillator balun output port 217 are different by 180°, and the local oscillator balun comprehensive port 211 is completely matched with its characteristic impedance, and no energy is reflected. The equivalent relationship is expressed as follows:

[0080] S 11 =0 can be equivalent to Z S

[0081] wherein S 11 represents the reflection coefficient of the local oscillator balun comprehensive port 211 network when the first local oscillator balun output port 216 and the second local oscillator balun output port 217 are matched. Z S represents the characteristic impedance of the local oscillator balun comprehensive port 211.

[0082] The specific expressions of the input impedance Z

[0083]

[0084] The matching relationship between the odd mode impedance and the even mode impedance of the fourth local oscillator balun microstrip line 213d and the characteristic impedance of the local oscillator balun comprehensive port 211 is expressed as follows:

[0085]

[0086] From the above formula, in order to make the output signals of the balun achieve ideal amplitude and phase consistency, the odd mode impedance and the even mode impedance required by the third local oscillator balun microstrip line 213c and the fourth local oscillator balun microstrip line 213d are not completely the same, i.e. and ​Therefore, on the basis of the completely symmetrical balun structure, the local oscillator balun 210, the radio frequency balun 220 and the local oscillator coupling line 230 in the embodiment of the application all adopt the three-layer vertical metal layer structure balun, and the isolation of the passive double balanced mixer is improved through the metal layer connection mode of the via and the symmetrical microstrip line layout.

[0087] With reference to Figure 8 and Figure 11 The mixer realizes low conversion loss and excellent isolation performance in the super wideband range of 2-22GHz. The typical down-conversion loss is about 10dB; the typical local oscillator signal-radio frequency signal (LO-RF) isolation is about 55dB, the typical local oscillator signal-intermediate frequency signal (LO-IF) isolation is about 40dB, and the typical radio frequency signal-intermediate frequency signal (RF-IF) isolation is about 42dB.

[0088] The implementation principle of the passive double balanced mixer in the embodiment of the application is as follows: the local oscillator balun 210 and the radio frequency balun 220 in the passive double balanced mixer both adopt the three-layer metal balun structure, the efficient coupling of the differential signal is realized through the mode of flowing into the vertically overlapped microstrip line from the center feed-in point of the third layer metal structure in the balun structure, and the amplitude and phase consistency of the differential signal is further improved through the local oscillator coupling line 230 of the three-layer metal structure. In the super wideband range, it is ensured that the local oscillator signal and the radio frequency signal are effectively converted into high-quality differential signals, so as to improve the isolation and spurious suppression performance of the passive double balanced mixer. In addition, the structure also provides stable and efficient mixing performance for the passive double balanced mixer, and has the characteristics of low conversion loss.

[0089] The above are the preferred embodiments of the application, and do not limit the protection scope of the application, so: all equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A passive double balanced mixer characterized by, The application relates to a local oscillator balun (210), a local oscillator coupling line (230), a diode ring (240), a radio frequency balun (220) and an intermediate frequency lead-out circuit (250). The local oscillator balun (210) has a local oscillator balun comprehensive port (211), a local oscillator balun center ground port (215), a first local oscillator balun output port (216), a second local oscillator balun output port (217), a first local oscillator balun metal layer, a second local oscillator balun metal layer and a third local oscillator balun metal layer which are sequentially stacked; the third local oscillator balun metal layer is provided with a local oscillator balun center feed-in point (212), a first local oscillator balun microstrip line (213a) and a second local oscillator balun microstrip line (213b) which are symmetrically arranged with respect to the local oscillator balun center feed-in point (212), the local oscillator balun center feed-in point (212) is connected to the local oscillator balun comprehensive port (211); the second local oscillator balun metal layer is provided with a local oscillator balun center intersection point (214), a third local oscillator balun microstrip line (213c) and a fourth local oscillator balun microstrip line (213d) which are symmetrically arranged with respect to the local oscillator balun center intersection point (214), the local oscillator balun center intersection point (214) is connected to the local oscillator balun center ground port (215), the second local oscillator balun microstrip line (213b) and the third local oscillator balun microstrip line (213c) are vertically overlapped, and the first local oscillator balun microstrip line (213a) and the fourth local oscillator balun microstrip line (213d) are vertically overlapped; the first local oscillator balun metal layer is connected to the first local oscillator balun microstrip line (213a), the second local oscillator balun microstrip line (213b), the third local oscillator balun microstrip line (213c) and the fourth local oscillator balun microstrip line (213d), and the first local oscillator balun metal layer is further connected to the first local oscillator balun output port (216), the second local oscillator balun output port (217) and a ground terminal; wherein a local oscillator signal flows into the local oscillator balun (210) from the local oscillator balun center feed-in point (212), and is coupled to form a first differential local oscillator signal component and a second differential local oscillator signal component through the first local oscillator balun microstrip line (213a), the second local oscillator balun microstrip line (213b), the third local oscillator balun microstrip line (213c) and the fourth local oscillator balun microstrip line (213d), the first differential local oscillator signal component flows out from the first local oscillator balun output port (216), and the second differential local oscillator signal component flows out from the second local oscillator balun output port (217). ​ 2. The passive double balanced mixer of claim 1, wherein, The first local oscillator balun metal layer is connected with the first local oscillator balun microstrip line (213a), the second local oscillator balun microstrip line (213b), the third local oscillator balun microstrip line (213c) and the fourth local oscillator balun microstrip line (213d), wherein the first end of the first local oscillator balun microstrip line (213a) is connected to the local oscillator balun center feeding point (212), the second end of the first local oscillator balun microstrip line (213a) is connected to the first local oscillator balun metal layer and is connected to the second local oscillator balun output port (217) through the first local oscillator balun metal layer; the first end of the second local oscillator balun microstrip line (213b) is connected to the local oscillator balun center feeding point (212), the second end of the second local oscillator balun microstrip line (213b) is connected to the first local oscillator balun metal layer and is grounded through the first local oscillator balun metal layer; the first end of the third local oscillator balun microstrip line (213c) is connected to the local oscillator balun center intersection (214), the second end of the third local oscillator balun microstrip line (213c) is connected to the first local oscillator balun metal layer and is connected to the first local oscillator balun output port (216) through the first local oscillator balun metal layer; the first end of the fourth local oscillator balun microstrip line (213d) is connected to the local oscillator balun center intersection (214), the second end of the fourth local oscillator balun microstrip line (213d) is connected to the first local oscillator balun metal layer and is grounded through the first local oscillator balun metal layer.

3. The passive double balanced mixer of claim 2, wherein, The second end of the first local oscillator balun microstrip line (213a), the second end of the second local oscillator balun microstrip line (213b), the second end of the third local oscillator balun microstrip line (213c) and the second end of the fourth local oscillator balun microstrip line (213d) are all connected to the first local oscillator balun metal layer through the via.

4. The passive double balanced mixer of claim 1, wherein, The radio frequency balun (220) comprises a radio frequency balun comprehensive port (221), a radio frequency balun center ground port (225), a first radio frequency balun output port (226), a second radio frequency balun output port (227), and a first radio frequency balun metal layer, a second radio frequency balun metal layer and a third radio frequency balun metal layer arranged in sequence; the third radio frequency balun metal layer is configured with a radio frequency balun center feed-in point (222) and a first radio frequency balun microstrip line (223a) and a second radio frequency balun microstrip line (223b) symmetrically arranged with respect to the radio frequency balun center feed-in point (222), the radio frequency balun center feed-in point (222) is connected to the radio frequency balun comprehensive port (221); the second radio frequency balun metal layer is configured with a radio frequency balun center intersection point (224) and a third radio frequency balun microstrip line (223c) and a fourth radio frequency balun microstrip line (223d) symmetrically arranged with respect to the radio frequency balun center intersection point (224), the radio frequency balun center intersection point (224) is connected to the radio frequency balun center ground port (225), the second radio frequency balun microstrip line (223b) and the third radio frequency balun microstrip line (223c) are vertically overlapped, and the first radio frequency balun microstrip line (223a) and the fourth radio frequency balun microstrip line (223d) are vertically overlapped; the first radio frequency balun metal layer is connected with the first radio frequency balun microstrip line (223a), the second radio frequency balun microstrip line (223b), the third radio frequency balun microstrip line (223c) and the fourth radio frequency balun microstrip line (223d), and the first radio frequency balun metal layer is also connected to the first radio frequency balun output port (226), the second radio frequency balun output port (227) and a ground terminal; wherein the radio frequency signal flows into the radio frequency balun (220) from the radio frequency balun center feed-in point (222), and is coupled to form a first differential radio frequency signal component and a second differential radio frequency signal component through the first radio frequency balun microstrip line (223a), the second radio frequency balun microstrip line (223b), the third radio frequency balun microstrip line (223c) and the fourth radio frequency balun microstrip line (223d), the first differential radio frequency signal component flows out from the first radio frequency balun output port (226), and the second differential radio frequency signal component flows out from the second radio frequency balun output port (227).

5. The passive double balanced mixer of claim 4, wherein, The first radio frequency balun metal layer is connected with the first radio frequency balun microstrip line (223a), the second radio frequency balun microstrip line (223b), the third radio frequency balun microstrip line (223c) and the fourth radio frequency balun microstrip line (223d); wherein the first end of the first radio frequency balun microstrip line (223a) is connected to the radio frequency balun center feeding point (222), and the second end of the first radio frequency balun microstrip line (223a) is connected to the first radio frequency balun metal layer and connected to the second radio frequency balun output port (227) through the first radio frequency balun metal layer; the first end of the second radio frequency balun microstrip line (223b) is connected to the radio frequency balun center feeding point (222), and the second end of the second radio frequency balun microstrip line (223b) is connected to the first radio frequency balun metal layer and grounded through the first radio frequency balun metal layer; the first end of the third radio frequency balun microstrip line (223c) is connected to the radio frequency balun center intersection (224), and the second end of the third radio frequency balun microstrip line (223c) is connected to the first radio frequency balun metal layer and connected to the first radio frequency balun output port (226) through the first radio frequency balun metal layer; the first end of the fourth radio frequency balun microstrip line (223d) is connected to the radio frequency balun center intersection (224), and the second end of the fourth radio frequency balun microstrip line (223d) is connected to the first radio frequency balun metal layer and grounded through the first radio frequency balun metal layer.

6. The passive double balanced mixer of claim 5, wherein, The second end of the first radio frequency balun microstrip line (223a), the second end of the second radio frequency balun microstrip line (223b), the second end of the third radio frequency balun microstrip line (223c) and the second end of the fourth radio frequency balun microstrip line (223d) are all connected to the first radio frequency balun metal layer through the via.

7. The passive double balanced mixer of claim 4, wherein, The local oscillation coupling line (230) comprises a first local oscillation coupling line input port (231), a second local oscillation coupling line input port (232), a local oscillation coupling line center ground port (235), a first local oscillation coupling line output port (236), a second local oscillation coupling line output port (237), and a first local oscillation coupling metal layer, a second local oscillation coupling metal layer and a third local oscillation coupling metal layer which are sequentially stacked; wherein the second local oscillation coupling metal layer is configured with a first local oscillation coupling line center intersection (233) and a first local oscillation coupling microstrip line (234a) and a second local oscillation coupling microstrip line (234b) which are symmetrically arranged with respect to the first local oscillation coupling line center intersection (233), the first local oscillation coupling line center intersection (233) is connected to the local oscillation coupling line center ground port (235), the third local oscillation coupling metal layer is configured with a second local oscillation coupling line center intersection (238) and a third local oscillation coupling microstrip line (234c) and a fourth local oscillation coupling microstrip line (234d) which are symmetrically arranged with respect to the second local oscillation coupling line center intersection (238), the second local oscillation coupling line center intersection (238) is connected to the intermediate frequency lead-out circuit (250), the first local oscillation coupling microstrip line (234a) and the third local oscillation coupling microstrip line (234c) are vertically overlapped, and the second local oscillation coupling microstrip line (234b) and the fourth local oscillation coupling microstrip line (234d) are vertically overlapped; the first local oscillation coupling metal layer is connected with the first local oscillation coupling microstrip line (234a), the second local oscillation coupling microstrip line (234b), the third local oscillation coupling microstrip line (234c) and the fourth local oscillation coupling microstrip line (234d), and the first local oscillation coupling metal layer is also connected to the first local oscillation coupling line output port (236), the second local oscillation coupling line output port (237) and the local oscillation coupling line center ground port (235); wherein the first differential local oscillation signal component flows into the local oscillation coupling line (230) from the first local oscillation coupling line input port (231), the second differential local oscillation signal component flows into the local oscillation coupling line (230) from the second local oscillation coupling line input port (232), is coupled through the first local oscillation coupling microstrip line (234a), the second local oscillation coupling microstrip line (234b), the third local oscillation coupling microstrip line (234c) and the fourth local oscillation coupling microstrip line (234d), and the first differential local oscillation signal component flows out from the first local oscillation coupling line output port (236), and the second differential local oscillation signal component flows out from the second local oscillation coupling line output port (237).

8. The passive double balanced mixer of claim 7, wherein, The first local oscillator coupling metal layer is connected with the first local oscillator coupling microstrip line (234a), the second local oscillator coupling microstrip line (234b), the third local oscillator coupling microstrip line (234c) and the fourth local oscillator coupling microstrip line (234d), wherein a first end of the first local oscillator coupling microstrip line (234a) is connected to the first local oscillator coupling line input port (231), a second end of the first local oscillator coupling microstrip line (234a) is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line center intersection (233) through the first local oscillator coupling metal layer; a first end of the second local oscillator coupling microstrip line (234b) is connected to the second local oscillator coupling line input port (232), a second end of the second local oscillator coupling microstrip line (234b) is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line center intersection (233) through the first local oscillator coupling metal layer; a first end of the third local oscillator coupling microstrip line (234c) is connected to the second local oscillator coupling line center intersection (238), a second end of the third local oscillator coupling microstrip line (234c) is connected to the first local oscillator coupling metal layer and connected to the first local oscillator coupling line output port (236) through the first local oscillator coupling metal layer; a first end of the fourth local oscillator coupling microstrip line (234d) is connected to the second local oscillator coupling line center intersection (238), a second end of the fourth local oscillator coupling microstrip line (234d) is connected to the first local oscillator coupling metal layer and connected to the second local oscillator coupling line output port (237) through the first local oscillator coupling metal layer.

9. The passive double balanced mixer of claim 7, wherein, The diode ring (240) comprises a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, a cathode of the first diode D1 is connected to a cathode of the second diode D2 and forms a first diode ring port (241), an anode of the second diode D2 is connected to a cathode of the third diode D3 and forms a second diode ring port (242), an anode of the third diode D3 is connected to an anode of the fourth diode D4 and forms a third diode ring port (243), a cathode of the fourth diode D4 is connected to an anode of the first diode D1 and forms a fourth diode ring port (244); the first diode ring port (241) is connected to the first local oscillator coupling line output port (236), the second diode ring port (242) is connected to the second radio frequency bar output port (227), the third diode ring port (243) is connected to the second local oscillator coupling line output port (237), and the fourth diode ring port (244) is connected to the first radio frequency bar output port (226).

10. The passive double balanced mixer of claim 7, wherein, The intermediate frequency leading circuit (250) comprises an intermediate frequency metal layer and an intermediate frequency port (252), and an intermediate frequency signal flows into or out of the intermediate frequency port (252); wherein an intermediate frequency microstrip line (251) is arranged in the intermediate frequency metal layer, a first end of the intermediate frequency microstrip line (251) is connected to the second local oscillator coupling line center intersection (238), and a second end of the intermediate frequency microstrip line (251) is connected to the intermediate frequency port (252).

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