A miniaturized broadband 3dB 90° coupler

Abstract

The present invention relates to a miniaturized wideband 3dB 90° coupler, comprising: a dielectric substrate, on which a coupling module, a band widening module and a port module are arranged in sequence from the center to the outside; the coupling module is used to couple an input signal; the band widening module is used to widen the band of the coupled signal; and the port module is used for signal interaction inside and outside the coupler. The present invention designs and proposes a miniaturized wideband 3dB 90° coupler structure, which has the advantages of miniaturization and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of couplers, and in particular to a miniaturized broadband 3dB 90° coupler. Background Art

[0002] The coupler is a passive microwave device, usually a four-port device, divided into an input port, an output port, a coupling port and an isolation port. The coupler can be designed with any power distribution ratio and is widely used in power distribution and power synthesis. The 3dB 90° coupler is used to evenly divide the input signal into two paths, with a 90° phase shift between the two paths. However, in the prior art, the first solution is to use a wideband 3dB 90° coupler with a distributed microstrip transmission line structure. This form can achieve low production costs, but the space required for placement is still relatively large; the second solution is to use a wideband 3dB 90° coupler designed with an integrated circuit. This form can achieve a relatively small footprint, but the market price is high. Summary of the invention

[0003] The purpose of the present invention is to provide a miniaturized broadband 3dB 90° coupler to solve the problems existing in the above-mentioned prior art and realize a miniaturized and low-cost coupler structure.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A miniaturized wide-band 3dB 90° coupler comprises: a dielectric substrate, on which a coupling module, a frequency band widening module and a port module are sequentially arranged from the center to the outside;

[0006] The coupling module is used to couple the input signal;

[0007] The frequency band widening module is used to widen the frequency band of the coupled signal;

[0008] The port module is used for signal interaction inside and outside the coupler.

[0009] Optionally, the port module includes: an input port, an output port, a coupling port and an isolation port;

[0010] The input port is used to receive an input signal from an external signal source;

[0011] The output port is used to output the signal processed by the coupler;

[0012] The coupling port is used for signal transmission between the input port and the output port;

[0013] The isolation port is used to implement signal isolation in the circuit.

[0014] Optionally, the frequency band widening module includes: four frequency band widening units; each used to widen the frequency band of the coupled signal;

[0015] The first frequency band widening unit includes: an inductor L3, a capacitor C4, an inductor L8, and a capacitor C7;

[0016] Among them, the inductor L3 is connected in series with the capacitor C4, the inductor L8 is connected in series with the capacitor C7, and the capacitor C4 and the inductor L8 are both grounded; the circuit after the inductor L3 and the capacitor C7 are connected in parallel is connected to the input port; the inductor L3 is connected to the third frequency band widening unit and the coupling module respectively; the circuit after the capacitor C7 is connected in parallel is connected to the second frequency band widening unit and the coupling module respectively; the inductor L3 and the capacitor C4 are connected in series with the third frequency band widening unit;

[0017] The second frequency band widening unit includes: an inductor L10, a capacitor C10, an inductor L11, and a capacitor C11;

[0018] Among them, the inductor L10 is connected in parallel with the capacitor C11, the capacitor C10 is connected in parallel with the inductor L11, and the capacitor C10 and the inductor L11 are both grounded; the circuit after the capacitor C11 and the inductor L11 are connected in parallel is connected to the output port; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the circuit after the inductor L8 and the capacitor C7 are connected in parallel and the coupling module; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module;

[0019] The third frequency band widening unit includes: an inductor L1, a capacitor C2, an inductor L2, and a capacitor C1;

[0020] Among them, the inductor L1 is connected in parallel with the capacitor C2, the inductor L2 is connected in parallel with the capacitor C1, the inductor L1 is connected in parallel with the capacitor C1, and the capacitor C2 and the inductor L2 are both grounded; the circuit after the inductor L1 and the capacitor C1 are connected in parallel is connected to the coupling port; the circuit after the inductor L1 and the capacitor C2 are connected in parallel is respectively connected to the circuit after the inductor L3 and the capacitor C4 are connected in parallel, and the coupling module; the circuit after the inductor L2 and the capacitor C1 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module;

[0021] The fourth frequency band widening unit includes: an inductor L6, a capacitor C6, an inductor L9, and a capacitor C3;

[0022] Among them, the inductor L6 is connected in parallel with the capacitor C3, the capacitor C6 is connected in parallel with the inductor L9, the inductor L9 is connected in parallel with the capacitor C3, and the capacitor C6 and the inductor L6 are both grounded; the circuit after the inductor L6 and the capacitor C3 are connected in parallel is respectively connected to the circuit after the inductor L2 and the capacitor C1 are connected in parallel and the coupling module; the circuit after the capacitor C6 and the inductor L9 are connected in parallel is respectively connected to the circuit after the inductor L10 and the capacitor C11 are connected in parallel and the coupling module; the circuit after the inductor L9 and the capacitor C3 are connected in parallel is connected to the isolation port.

[0023] Optionally, the coupling module includes: an inductor L4, an inductor L5, a resistor R1, a capacitor C9, a capacitor C8, an inductor L7, and a capacitor C5;

[0024] Inductor L7 and capacitor C5 are connected in parallel to form a parallel unit, inductor L4 and inductor L5 are connected in parallel to form a parallel unit, and capacitor C5 and capacitor C9 are connected in parallel to form a parallel unit. The three parallel units are connected in series;

[0025] The capacitor C4 of the first frequency extension unit is connected in parallel with the capacitor C2 of the third frequency extension unit, and then connected in series with the inductor L4 of the coupling module;

[0026] The capacitor C10 of the second frequency extension unit is connected in parallel with the capacitor C6 of the fourth frequency extension unit, and then connected in series with the resistor R2 and the inductor L5 of the coupling module;

[0027] The inductor L8 of the first frequency extension unit is connected in parallel with the inductor L10 of the second frequency extension unit, and then connected in series with the capacitor C8 of the coupling module;

[0028] The inductor L2 of the third frequency extension unit and the inductor L6 of the fourth frequency extension unit are connected in parallel, and then connected in series with the resistor R1 and the capacitor C9 of the coupling module.

[0029] The beneficial effects of the present invention are:

[0030] The present invention proposes a miniaturized wideband 3dB 90° coupler structure, which includes: a dielectric substrate, on which a coupling module, a band widening module and a port module are arranged in sequence from the center to the outside; the coupling module is used to couple the input signal; the band widening module is used to widen the band of the coupled signal; and the port module is used for the interaction of the signal inside and outside the coupler. The advantages of the coupler structure are: miniaturization and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 is a schematic diagram of a miniaturized broadband 3dB 90° coupler according to an embodiment of the present invention;

[0033] Figure 2 A top view of a miniaturized broadband 3dB 90° coupler according to an embodiment of the present invention;

[0034] Figure 3 A back view of a miniaturized broadband 3dB 90° coupler according to an embodiment of the present invention;

[0035] Figure 4 A pad microstrip line structure diagram of a miniaturized broadband 3dB 90° coupler according to an embodiment of the present invention;

[0036] Figure 5 is a full response variation curve diagram of a miniaturized wide-band 3dB 90° coupler according to an embodiment of the present invention;

[0037] Figure 6 is an output response variation curve diagram of a miniaturized wide-band 3dB 90° coupler according to an embodiment of the present invention;

[0038] Figure 7 A 90° phase variation curve diagram of a miniaturized wideband 3dB 90° coupler according to an embodiment of the present invention;

[0039] Among them, 1. Input end microstrip line; 2. Output end microstrip line; 3. Coupling end microstrip line; 4. Isolation end microstrip line; 5. Capacitor; 6. Inductor; 7. Resistor; 8. Back bridge microstrip line; 9. Metal through hole; 10. Pad; 11. Circuit dielectric substrate. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] The terms in this embodiment are explained as follows:

[0043] Lumped devices: components such as capacitors and inductors;

[0044] Wideband: The device structure design function can cover a wide frequency range;

[0045] 3dB means that the input signal is split into two and two signals are output;

[0046] 90° means that the phase difference between the two output signals is 90°;

[0047] This embodiment provides a miniaturized wide-band 3dB 90° coupler, comprising: a dielectric substrate, on which a coupling module, a band widening module and a port module are sequentially arranged from the center to the outside;

[0048] A coupling module, used for coupling an input signal;

[0049] A frequency band widening module, used for widening the frequency band of the coupled signal;

[0050] Port modules are used for signal interaction inside and outside the coupler.

[0051] Further, the port module includes: an input port, an output port, a coupling port and an isolation port;

[0052] An input port, used for receiving an input signal from an external signal source;

[0053] An output port, used to output the signal processed by the coupler;

[0054] A coupling port, used for signal transmission between the input port and the output port;

[0055] Isolation port is used to achieve signal isolation in the circuit.

[0056] Further, the frequency band widening module includes: a first frequency band widening unit, a second frequency band widening unit, a third frequency band widening unit, and a fourth frequency band widening unit;

[0057] The first frequency band widening unit includes: an inductor L3, a capacitor C4, an inductor L8, and a capacitor C7;

[0058] Among them, the inductor L3 is connected in series with the capacitor C4, the inductor L8 is connected in series with the capacitor C7, and the capacitor C4 and the inductor L8 are both grounded; the circuit after the inductor L3 and the capacitor C7 are connected in parallel is connected to the input port; the inductor L3 is connected to the third frequency band widening unit and the coupling module respectively; the circuit after the capacitor C7 is connected in parallel is connected to the second frequency band widening unit and the coupling module respectively;

[0059] The second frequency band widening unit includes: an inductor L10, a capacitor C10, an inductor L11, and a capacitor C11;

[0060] Among them, the inductor L10 is connected in parallel with the capacitor C11, the capacitor C10 is connected in parallel with the inductor L11, and the capacitor C10 and the inductor L11 are both grounded; the circuit after the capacitor C11 and the inductor L11 are connected in parallel is connected to the output port; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the circuit after the inductor L8 and the capacitor C7 are connected in parallel and the coupling module; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module;

[0061] The third frequency band widening unit includes: an inductor L1, a capacitor C2, an inductor L2, and a capacitor C1;

[0062] Among them, the inductor L1 is connected in parallel with the capacitor C2, the inductor L2 is connected in parallel with the capacitor C1, the inductor L1 is connected in parallel with the capacitor C1, and the capacitor C2 and the inductor L2 are both grounded; the circuit after the inductor L1 and the capacitor C1 are connected in parallel is connected to the coupling port; the circuit after the inductor L1 and the capacitor C2 are connected in parallel is respectively connected to the circuit after the inductor L3 and the capacitor C4 are connected in parallel, and the coupling module; the circuit after the inductor L2 and the capacitor C1 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module;

[0063] The fourth frequency band widening unit includes: an inductor L6, a capacitor C6, an inductor L9, and a capacitor C3;

[0064] Among them, the inductor L6 is connected in parallel with the capacitor C3, the capacitor C6 is connected in parallel with the inductor L9, the inductor L9 is connected in parallel with the capacitor C3, and the capacitor C6 and the inductor L6 are both grounded; the circuit after the inductor L6 and the capacitor C3 are connected in parallel is respectively connected to the circuit after the inductor L2 and the capacitor C1 are connected in parallel and the coupling module; the circuit after the capacitor C6 and the inductor L9 are connected in parallel is respectively connected to the circuit after the inductor L10 and the capacitor C11 are connected in parallel and the coupling module; the circuit after the inductor L9 and the capacitor C3 are connected in parallel is connected to the isolation port.

[0065] Further, the coupling module includes: inductor L4, inductor L5, resistor R1, capacitor C9, capacitor C8, inductor L7, capacitor C5;

[0066] Inductor L7 and capacitor C5 are connected in parallel to form a parallel unit, inductor L4 and inductor L5 are connected in parallel to form a parallel unit, and capacitor C5 and capacitor C9 are connected in parallel to form a parallel unit. The three parallel units are connected in series;

[0067] The capacitor C4 of the first frequency extension unit is connected in parallel with the capacitor C2 of the third frequency extension unit, and then connected in series with the inductor L4 of the coupling module;

[0068] The capacitor C10 of the second frequency extension unit is connected in parallel with the capacitor C6 of the fourth frequency extension unit, and then connected in series with the resistor R2 and the inductor L5 of the coupling module;

[0069] The inductor L8 of the first frequency extension unit is connected in parallel with the inductor L10 of the second frequency extension unit, and then connected in series with the capacitor C8 of the coupling module;

[0070] The inductor L2 of the third frequency extension unit and the inductor L6 of the fourth frequency extension unit are connected in parallel, and then connected in series with the resistor R1 and the capacitor C9 of the coupling module.

[0071] Specifically, in this embodiment, the pad microstrip line structure is as follows: Figure 4 As shown, as an optimal implementation arrangement method, the arrangement of the band widening module on the dielectric substrate is as follows:

[0072] The frequency band widening module includes: a capacitor C4 vertically placed at the upper left corner of the dielectric substrate, and a capacitor C2 located on the right side of the capacitor C4 and placed in parallel with the capacitor C4, and a pad at the lower end of the capacitor C4 is connected to a pad at the lower end of the capacitor C2 by a microstrip line;

[0073] A horizontally placed inductor L1 is provided on the right side of the capacitor C2, and a pad at the lower end of the capacitor C2 is connected to a pad at the left end of the inductor L1 by a microstrip line;

[0074] A horizontally placed capacitor C1 is provided on the right side of the inductor L1;

[0075] A vertically placed inductor L2 is provided on the right side of the capacitor C1, and a pad at the right end of the capacitor C1 and a pad at the left end of the inductor L2 are connected by a microstrip line;

[0076] A horizontally placed inductor L6 is provided below the inductor L2, and a pad at the lower end of the inductor L2 is connected to a pad at the left end of the inductor L6 by a microstrip line;

[0077] A vertically placed capacitor C3 is provided below the inductor L6, and a pad at the left end of the inductor L6 and a pad at the upper end of the capacitor C3 are connected by a microstrip line;

[0078] A vertically placed inductor L9 is provided below the capacitor C3;

[0079] A vertically placed capacitor C6 is provided below the inductor L9, and a pad at the lower end of the inductor L9 and a pad at the upper end of the capacitor C6 are connected by a microstrip line;

[0080] A vertically placed capacitor C10 is provided on the left side of the capacitor C6, and a pad at the upper end of the capacitor C6 is connected to a pad at the upper end of the capacitor C10 by a microstrip line;

[0081] A horizontally placed inductor L11 is provided on the left side of the capacitor C10, and a pad at the upper end of the capacitor C10 and a pad at the right end of the inductor L11 are connected by a microstrip line;

[0082] A horizontally placed capacitor C11 is provided on the left side of the inductor L11;

[0083] A vertically placed inductor L10 is provided on the left side of the capacitor C11, and a pad at the left end of the capacitor C11 and a pad at the upper end of the inductor L10 are connected by a microstrip line;

[0084] A horizontally placed inductor L8 is arranged above the inductor L10, and a pad at the upper end of the inductor L10 is connected to a pad at the right end of the inductor L8 by a microstrip line;

[0085] A vertically placed capacitor C7 is provided above the inductor L8, and a pad at the right end of the inductor L8 and a pad at the lower end of the capacitor C7 are connected by a microstrip line;

[0086] A vertically placed inductor L3 is provided above the capacitor C7;

[0087] The pad at the upper end of the inductor L3 and the pad at the lower end of the capacitor C4 are connected by a microstrip line.

[0088] Specifically, the arrangement of the coupling module on the dielectric substrate is as follows:

[0089] A vertically placed inductor L4 is arranged at the lower side of the inductor L1, and a pad at the upper end of the inductor L4 is connected to a pad at the left end of the inductor L1 by a microstrip line;

[0090] A horizontally placed inductor L5 is provided on the right side of the inductor L4, and a pad at the lower end of the inductor L4 is connected to a pad at the left end of the inductor L5 by a microstrip line;

[0091] A vertically placed capacitor C5 is provided below the inductor L5, and a pad at the left end of the inductor L5 and a pad at the upper end of the capacitor C5 are connected by a microstrip line;

[0092] A vertically placed inductor L7 is provided on the left side of the capacitor C5, and the pads at the upper and lower ends of the capacitor C5 and the pads at the upper and lower ends of the inductor L7 are connected with microstrip lines respectively;

[0093] A vertically placed capacitor C8 is provided on the left side of the inductor L7, and a pad at the lower end of the inductor L7 and a pad at the upper end of the capacitor C8 are connected by a microstrip line;

[0094] The pad at the lower end of capacitor C8 is connected to the pad on the left side of capacitor C11 by a microstrip line;

[0095] The pad at the upper end of the inductor L7 is connected to the pad at the lower end of the inductor L4 by a microstrip line;

[0096] A vertically placed resistor R1 is provided on the right side of the inductor L5, and a pad on the right side of the inductor L5 is connected to a pad on the upper end of the resistor R1 by a microstrip line;

[0097] The pad at the upper end of the resistor R1 and the pad at the right end of the capacitor C1 are connected by a microstrip line;

[0098] A horizontally placed capacitor C9 is provided below the resistor R1 , and a pad at the lower end of the resistor R1 and a pad at the right end of the capacitor C9 are connected by a microstrip line.

[0099] Further, as an optimal implementation arrangement method, the microstrip line of the input port is connected to the pad at the upper end of the capacitor C7 and the pad at the lower end of the inductor L3 respectively;

[0100] The microstrip line of the output port is connected to the pad at the right end of the capacitor C11 and the pad at the left end of the inductor L11 respectively;

[0101] The microstrip line of the coupling port is connected to the pad at the right end of the inductor L1 and the pad at the left end of the capacitor C1 respectively;

[0102] The microstrip line of the isolation port is connected to the pad at the lower end of the capacitor C3 and the pad at the upper end of the inductor L9 respectively.

[0103] Further, the coupler further comprises: a back bridge microstrip line;

[0104] The back bridge microstrip line connects the pad at one end of the resistor R2 to the metal through hole 9 .

[0105] Further, the metal through hole 9 connects the pad at one end of the inductor L5 on the upper surface of the dielectric substrate to the pad at one end of the resistor R22 on the lower surface;

[0106] The metal through hole 9 connects a pad at one end of the inductor L11 on the upper surface of the dielectric substrate to a pad at one end of the resistor R22 on the lower surface.

[0107] Specifically, in this embodiment, Figure 2 As shown, the miniaturized broadband 3dB 90° coupler includes: an input end microstrip line 1; an output end microstrip line 2; a coupling end microstrip line 3; an isolation end microstrip line 4; a capacitor 5; an inductor 6; a resistor 7; a back bridge microstrip line 8; a metal through hole 9; a pad 10 for placing capacitors, inductors, and resistors; and a circuit dielectric substrate 11.

[0108] The input end microstrip line 1 is connected to the pad 10 of the capacitor C7 and the inductor L3, the output end microstrip line 2 is connected to the pad 10 of the capacitor C11 and the inductor L11, the coupling end microstrip line 3 is connected to the pad 10 of the capacitor C1 and the inductor L1, and the isolation end microstrip line 4 is connected to the pad 10 of the capacitor C3 and the inductor L9.

[0109] Figure 1 The components enclosed by dotted circles are external devices. The connections are described as follows:

[0110] A pad at one end of the inductor L3 is connected to a pad at one end of the capacitor C4 by a microstrip line;

[0111] A pad at one end of capacitor C4 is connected to a pad at one end of capacitor C2 by a microstrip line;

[0112] The pad at one end of the capacitor C2 is connected to the pad at one end of the inductor L1 by a microstrip line;

[0113] The pad at one end of the capacitor C1 is connected to the pad at one end of the inductor L2 by a microstrip line;

[0114] The pad at one end of the inductor L2 is connected to the pad at one end of the inductor L6 by a microstrip line;

[0115] A pad at one end of the inductor L6 is connected to a pad at one end of the capacitor C3 by a microstrip line;

[0116] The pad at one end of the inductor L9 is connected to the pad at one end of the capacitor C6 by a microstrip line;

[0117] A pad at one end of capacitor C6 is connected to a pad at one end of capacitor C10 by a microstrip line;

[0118] A pad at one end of the capacitor C10 is connected to a pad at one end of the inductor L11 by a microstrip line;

[0119] A pad at one end of the capacitor C11 is connected to a pad at one end of the inductor L10 by a microstrip line;

[0120] The pad at one end of the inductor L10 is connected to the pad at one end of the inductor L8 by a microstrip line;

[0121] A pad at one end of the inductor L8 is connected to a pad at one end of the capacitor C7 by a microstrip line;

[0122] The external capacitor and inductor connections are complete, and the schematic diagram is as follows Figure 1 As shown, the layout is connected as Figure 2 shown.

[0123] Figure 1 The components outside the dotted line are internal components, and their connections are described as follows:

[0124] A pad at one end of the inductor L1 is connected to a pad at one end of the inductor L4 by a microstrip line;

[0125] A pad at one end of the inductor L4 is connected to a pad at one end of the inductor L5 by a microstrip line;

[0126] A pad at one end of the inductor L5 is connected to a pad at one end of the capacitor C5 by a microstrip line;

[0127] A pad at one end of the capacitor C5 is connected to a pad at one end of the inductor L7 by a microstrip line;

[0128] The pad at one end of the inductor L7 and the pad at one end of the capacitor C8 are connected by a microstrip line;

[0129] A pad at one end of capacitor C8 is connected to a pad at one end of capacitor C11 by a microstrip line;

[0130] The pad at one end of the inductor L7 is connected to the pad at one end of the inductor L4 by a microstrip line;

[0131] A pad at one end of the resistor R1 is connected to a pad at one end of the capacitor C1 by a microstrip line;

[0132] A pad at one end of the resistor R1 is connected to a pad at one end of the capacitor C9 by a microstrip line;

[0133] The internal capacitor, inductor and resistor connections are complete, and the schematic diagram is as follows Figure 1 As shown, the layout is connected as Figure 2 shown.

[0134] The back bridge microstrip line 8 connects the pad at one end of the resistor R2 to the metal through hole 9 .

[0135] The metal through hole 9 connects a pad at one end of the inductor L5 on the upper surface of the dielectric substrate 11 to a pad at one end of the resistor R22 on the lower surface.

[0136] Connect the pad at one end of the inductor L11 on the upper surface of the dielectric substrate 11 to the pad at one end of the resistor R22 on the lower surface.

[0137] The back bridge microstrip line connection is completed, and the schematic connection is as follows Figure 1 As shown, the layout is connected as Figure 2 , Figure 3 shown.

[0138] The technical principle of this embodiment is that the input impedance R is known to be 50 ohm, and the resonance frequency center fc=1400 MHz.

[0139] Depend on:

[0140] ①

[0141] ②

[0142] ③

[0143] L and C can be obtained.

[0144] because Figure 1 The values ​​of the capacitor and inductor devices within the dotted line range in the coupler schematic are consistent, so the formula can be used to calculate the values ​​of the capacitor and inductor in the dotted line.

[0145] That is, L1=L2=L3=L6=L8=L9=L10=L11=L

[0146] C1=C2=C3=C4=C6=C7=C10=C11=C

[0147] In order to increase the bandwidth of the frequency center and the frequency range of the 90° phase difference, a basic coupler circuit structure resonating at the frequency center of 1400MHz is introduced.

[0148] This structure divides the capacitor into two, forming capacitors C8 and C9, and divides the inductor into two, forming inductors L4 and L5.

[0149] The inductance value of L4 and L5 is L / 2, and the capacitance value of C8 and C9 is 2C.

[0150] The inductance value of L7 is 0.7L, and the capacitance value of C5 is 1.5C.

[0151] Furthermore, the resistors R1 and R2 are both 0 ohm, and their function is to act as a bridge to prevent the negative impact of the excessively long microstrip line on the coupler.

[0152] Furthermore, the specifications of capacitors, inductors, and resistors are selected to be 0402 (1mm×0.5mm).

[0153] Furthermore, the capacitor used was Murata's "GRM15" series, and the inductor used was Murata's "LQG15HH" series.

[0154] Furthermore, in circuit design, the inductors of lumped components cannot be placed close to each other in parallel, which will easily lead to inductance synthesis and a decrease in inductance value.

[0155] Furthermore, the width of the microstrip line used to connect the components is 0.5 mm.

[0156] Furthermore, the circuit dielectric substrate is FR4.

[0157] Furthermore, the impedance of the input microstrip line is 50 ohm.

[0158] like Figure 5As shown, the S1.1 parameter of the coupler is less than -20dB in the frequency band from 1.1GHz to 1.7GHz. The coupler can achieve coverage between 1.1GHz and 1.7GHz, and the coupler can effectively transmit in this frequency band. The S2.1 and S3.1 parameters of the coupler are both between -3dB and -4dB in the frequency band from 1.1GHz to 1.7GHz, achieving the performance index of the 3dB coupler, so that the coupling has the function of nearly splitting the power in half. The S4.1 parameter of the coupler is less than 20dB in the frequency band from 1.1GHz to 1.7GHz, indicating that the coupler has excellent isolation. In summary, it can be concluded that the return loss and isolation of the coupler are both greater than 20dB in the frequency band from 1.1GHz to 1.7GHz. In the frequency band from 1.1GHz to 1.7GHz, the coupling degree is 3.6dB+0.2dB.

[0159] like Figure 6 As shown, the S2.1 and S3.1 parameters of the coupler are both between -3dB and -4dB in the 1.1GHz to 1.7GHz frequency band, achieving the performance index of a 3dB coupler, making the coupling have the function of nearly splitting the power in half. Figure 6 right Figure 5 The coupling parameters can be clearly seen. ).

[0160] like Figure 7 As shown, the phase difference between the output end and the coupling section of the coupler is between 88° and 90° in the 1.15GHz-1.61GHz frequency band, which satisfies the function of the coupler having a 90° phase difference.

[0161] This embodiment adopts a broadband 3dB 90° coupler with a distributed microstrip transmission line structure. This form can achieve low production costs, but the space required for placement is still relatively large. A broadband 3dB 90° coupler designed with integrated circuits can be relatively small, but the market price is high. The design of the present invention proposes a miniaturized broadband 3dB 90° coupler structure, which has the advantages of miniaturization and low cost. Mainly through comparison with similar products, using a microstrip line design, based on the design principle, the full-band coupler is very large in size, while the lumped device design of this embodiment is only the size of a fingernail (5mm*5mm).

[0162] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A miniaturized broadband 3dB 90° coupler, characterized in that: include: A dielectric substrate, on which a coupling module, a frequency band widening module and a port module are sequentially arranged from the center to the outside; The coupling module is used to couple the input signal; The frequency band widening module is used to widen the frequency band of the coupled signal; The port module is used for signal interaction inside and outside the coupler; The port module includes: an input port, an output port, a coupling port and an isolation port; The input port is used to receive an input signal from an external signal source; The output port is used to output the signal processed by the coupler; The coupling port is used for signal transmission between the input port and the output port; The isolation port is used to implement signal isolation in the circuit; The frequency band widening module comprises: four frequency band widening units; The first frequency band widening unit includes: an inductor L3, a capacitor C4, an inductor L8, and a capacitor C7; Among them, the inductor L3 is connected in series with the capacitor C4, the inductor L8 is connected in series with the capacitor C7, and the capacitor C4 and the inductor L8 are both grounded; the circuit after the inductor L3 and the capacitor C7 are connected in parallel is connected to the input port; the inductor L3 is connected to the third frequency band widening unit and the coupling module respectively; the capacitor C7 is connected to the second frequency band widening unit and the coupling module respectively; the inductor L3 is connected in series with the capacitor C4 and then connected to the third frequency band widening unit; The second frequency band widening unit includes: an inductor L10, a capacitor C10, an inductor L11, and a capacitor C11; Among them, the inductor L10 is connected in parallel with the capacitor C11, the capacitor C10 is connected in parallel with the inductor L11, and the capacitor C10 and the inductor L11 are both grounded; the circuit after the capacitor C11 and the inductor L11 are connected in parallel is connected to the output port; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the circuit after the inductor L8 and the capacitor C7 are connected in parallel and the coupling module; the circuit after the inductor L10 and the capacitor C11 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module; The third frequency band widening unit includes: an inductor L1, a capacitor C2, an inductor L2, and a capacitor C1; Among them, the inductor L1 is connected in parallel with the capacitor C2, the inductor L2 is connected in parallel with the capacitor C1, the inductor L1 is connected in parallel with the capacitor C1, and the capacitor C2 and the inductor L2 are both grounded; the circuit after the inductor L1 and the capacitor C1 are connected in parallel is connected to the coupling port; the circuit after the inductor L1 and the capacitor C2 are connected in parallel is respectively connected to the circuit after the inductor L3 and the capacitor C4 are connected in parallel, and the coupling module; the circuit after the inductor L2 and the capacitor C1 are connected in parallel is respectively connected to the fourth frequency band widening unit and the coupling module; The fourth frequency band widening unit includes: an inductor L6, a capacitor C6, an inductor L9, and a capacitor C3; Among them, the inductor L6 is connected in parallel with the capacitor C3, the capacitor C6 is connected in parallel with the inductor L9, the inductor L9 is connected in parallel with the capacitor C3, and the capacitor C6 and the inductor L6 are both grounded; the circuit after the inductor L6 and the capacitor C3 are connected in parallel is respectively connected to the circuit after the inductor L2 and the capacitor C1 are connected in parallel and the coupling module; the circuit after the capacitor C6 and the inductor L9 are connected in parallel is respectively connected to the circuit after the inductor L10 and the capacitor C11 are connected in parallel and the coupling module; the circuit after the inductor L9 and the capacitor C3 are connected in parallel is connected to the isolation port.

2. The miniaturized broadband 3dB 90° coupler according to claim 1, characterized in that: The coupling module includes: inductor L4, inductor L5, resistor R1, capacitor C9, capacitor C8, inductor L7, capacitor C5; Inductor L7 and capacitor C5 are connected in parallel to form a parallel unit, inductor L4 and inductor L5 are connected in parallel to form a parallel unit, capacitor C5 and capacitor C9 are connected in parallel to form a parallel unit; the three parallel units are connected in series; The capacitor C4 of the first frequency band widening unit is connected in parallel with the capacitor C2 of the third frequency band widening unit, and then connected in series with the inductor L4 of the coupling module; The capacitor C10 of the second frequency band widening unit is connected in parallel with the capacitor C6 of the fourth frequency band widening unit, and then connected in series with the resistor R2 and the inductor L5 of the coupling module; The inductor L8 of the first frequency band widening unit is connected in parallel with the inductor L10 of the second frequency band widening unit, and then connected in series with the capacitor C8 of the coupling module; The inductor L2 of the third frequency band widening unit and the inductor L6 of the fourth frequency band widening unit are connected in parallel, and then connected in series with the resistor R1 and the capacitor C9 of the coupling module.

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