阅读说明：本技术 一种紧凑型多线Marchand平面巴伦装置 (Compact multi-line Marchand plane balun device ) 是由 姚鸿飞 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种Marchand平面巴伦装置,该Marchand平面巴伦装置的电路结构中在主传输线输入端、末端、左耦合线和右耦合线接地位置并联MIM电容到底,从而缩短了传输线长度,显著减少了巴伦尺寸；左耦合线以及右耦合线并联电容接地位置,均上下对称地并联两个MIM电容,电容下极板连接到接地金属面上。该接地金属面通过上下两个对称的接地过孔,贯通介质基板,连接介质基板背后的金属地,降低了互联寄生电感,从而提高了电路的工作频率和带宽,并保证了电路良好的的幅度平衡度和相位平衡度。(The invention discloses a Marchand planar balun device.A MIM capacitor is connected to the bottom at the grounding positions of an input end, a tail end, a left coupling line and a right coupling line of a main transmission line in a circuit structure of the Marchand planar balun device, so that the length of the transmission line is shortened, and the size of the balun is obviously reduced; the left coupling line and the right coupling line are connected with the grounding positions of the capacitors in parallel and are connected with the two MIM capacitors in parallel in an up-down symmetrical mode, and the lower electrode plates of the capacitors are connected to the grounding metal surface. The grounding metal surface penetrates through the dielectric substrate through the upper and lower symmetrical grounding through holes and is connected with a metal ground behind the dielectric substrate, so that interconnection parasitic inductance is reduced, the working frequency and bandwidth of the circuit are improved, and the good amplitude balance degree and phase balance degree of the circuit are ensured.)

1. A compact multi-line Marchand planar balun device is characterized in that: the Marchand planar balun device comprises a first transmission line (1) and a second transmission line (2), a first coupling line (3) and a second coupling line (4) are arranged on two sides of the first transmission line (1), a third coupling line (5) and a fourth coupling line (6) are arranged on two sides of the second transmission line (2), one end of the first transmission line (1) is connected with an input end (7), a first capacitor (C1) is connected in parallel to the input end (7), and the first capacitor (C1) is grounded; the other end of the first transmission line (1) is connected with a second transmission line (2), and a second capacitor (C2) is connected between the other end of the second transmission line and the ground in parallel.

One sides of the first coupling line (3) and the second coupling line (4) close to the input end are connected with a third capacitor (C3) and a fourth capacitor (C4) in parallel to the ground, and the other ends of the first coupling line (3) and the second coupling line (4) are connected with a first output end (8).

One sides of the third coupling line (5) and the fourth coupling line (6) close to the grounding end of the second transmission line (2) are connected with a fifth capacitor (C5) and a sixth capacitor (C6) in parallel to the ground, and the other ends of the third coupling line (5) and the fourth coupling line (6) are connected with a second output end (9).

2. The compact multiline Marchand planar balun arrangement of claim 1, wherein: the first capacitor (C1) to the sixth capacitor (C6) use MIM single layer capacitors, MIM multilayer capacitors or interdigital capacitors coupled by means of transmission line slots.

3. The compact multiline Marchand planar balun arrangement of claim 1, wherein: the first transmission line (1) and the second transmission line (2) adopt microstrip lines or coplanar lines; when a coplanar line is adopted, the signal grounding is distributed on the metal grounds at the upper side and the lower side of the balun, and the metal grounds are connected with the metal on the back surface of the dielectric substrate through via holes or gold wires.

4. The compact multiline Marchand planar balun arrangement of claim 1, wherein: a seventh capacitor (C7) is connected between the first transmission line (1) and the second transmission line (2) in parallel and is grounded; an eighth capacitor (C8) is connected in parallel between the first output terminal (8) and the second output terminal (9).

5. The compact multiline Marchand planar balun arrangement of claim 1, wherein: the widths of the first transmission line (1), the first coupling line (3) and the second coupling line (4) can be the same or different; the spacing between the first coupling lines (3) of the first transmission line (1) and the spacing between the second coupling lines (4) of the first transmission line (1) can be the same or different;

the widths of the second transmission line (2), the third coupling line (5) and the fourth coupling line (6) can be the same or different; the distance between the third coupling lines (5) of the second transmission line (2) and the distance between the fourth coupling lines (6) of the second transmission line (2) can be the same or different.

6. The compact multiline Marchand planar balun arrangement of claim 1, wherein: a bias network (10) and an external voltage VCC are introduced between the grounding ends of the first coupling line (3) and the second coupling line (4) and the grounding ends of the third coupling line (5) and the fourth coupling line (6).

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a compact multi-line Marchand planar balun circuit.

Background

Balun (Balun) is a kind of conversion circuit that realizes balance to unbalance. In the early days, microwave balun circuits were mainly applied to the feeding system of the antenna, and later, this concept was introduced into the circuit design. With the increasing demand of broadband circuits in the application fields of modern communication, measurement, electronic countermeasure and the like, the balun is used as a key element in a push-pull power amplifier, a frequency multiplier and a balanced mixer, and the development of the balun is greatly improved. In the design of a broadband passive double-balanced mixer, the performance of a balun directly affects the overall performance of the mixer, and especially the bandwidth of the mixer is greatly restricted, so that designing a broadband balun with good operating characteristics is one of the core tasks of the double-balanced mixer.

Baluns can be divided into two broad classes, active baluns and passive baluns. The active balun can provide a very wide bandwidth and a certain gain in a small size, but the use of the active balun limits the overall dynamic range of the following amplifier, frequency multiplier or mixer and increases the extra power consumption. The passive balun does not consume any direct current power supply, the bandwidth can be wider, the performance is stable, and the linearity is good. Among passive baluns, a transmission line balun plays an extremely important role in microwave circuits and communication systems as a key device for transmitting an unbalanced signal, i.e., a balanced signal, and various structures have been proposed since the theory of baluns has been proposed. After decades of development, Marchand balun is widely used due to its excellent balance property, and different implementation modes of the structure, such as an axis form, a strip line form, a coupling microstrip line form and the like, have been proposed according to different application occasions. In order to further increase the coupling degree of the balun, the Marchand balun with double-side coupling, multi-side coupling and wide-side coupling is developed in succession. The use of a three-wire coupling structure instead of a two-wire coupling structure for simulation in a planar circuit design can improve the degree of coupling and at the same time can increase the bandwidth. However, in a planar circuit, a conventional Marchand planar balun is constructed of two quarter-wavelength coupled lines, as shown in fig. 1. The length of the optical fiber is in direct proportion to the wavelength of a working signal, and when the optical fiber is used in an integrated circuit, more chip area is occupied, so that the production and use cost is increased. With the development of a monolithic integrated circuit, the design of the circuit further tends to be miniaturized, the requirement on the miniaturization of the balun is higher and higher, a Marchand planar balun based on a spiral transformer structure appears in the prior art, the overall area of the balun can be effectively reduced through a large number of bending of transmission lines, and the defect that the passive balun is difficult to integrate is overcome. However, the parasitic effect is obvious, the self-resonant frequency is limited, and the balun can only be used in a low-frequency band of microwave frequency, and the loss of the balun is large.

Disclosure of Invention

One of the technical problems to be solved by the invention is to provide a compact miniaturized Marchand planar balun circuit which can be suitable for a millimeter wave frequency band and simultaneously keep low loss.

In order to solve the technical problem, the invention provides a compact multi-line Marchand planar balun device, wherein the Marchand planar balun circuit comprises a first transmission line 1 and a second transmission line 2, a first coupling line 3 and a second coupling line 4 are arranged on two sides of the first transmission line 1, a third coupling line 5 and a fourth coupling line 6 are arranged on two sides of the second transmission line 2, one end of the first transmission line 1 is connected with an input end 7, a first capacitor C1 is connected in parallel at the input end 7, namely the inlet of the first transmission line 1, and the first capacitor C1 is grounded; the other end of the first transmission line 1 is connected with the second transmission line 2, and a second capacitor C2 is connected between the other end of the second transmission line and the ground terminal in parallel.

The side of the first coupling line 3 and the second coupling line 4 close to the input end is connected with a third capacitor C3 and a fourth capacitor C4 in parallel to the ground, and the other end of the first coupling line 3 and the other end of the second coupling line 4 are connected with a first output end 8.

One sides of the third coupling line 5 and the fourth coupling line 6 close to the ground end of the second transmission line 2 are connected with a fifth capacitor C5 and a sixth capacitor C6 in parallel to the ground, and the other ends of the third coupling line 5 and the fourth coupling line 6 are connected with the second output end 9.

In one embodiment, the first to sixth capacitors C1 to C6 use MIM single layer capacitors, MIM multilayer capacitors or interdigital capacitors coupled by means of transmission line slots.

In one embodiment, the first transmission line and the second transmission line are microstrip lines or coplanar lines; when a coplanar line is adopted, the signal grounding layout is arranged on the metal grounds at the upper side and the lower side of the transmission line, and the metal grounds are connected with the metal on the back surface of the dielectric substrate.

In one embodiment, a parallel seventh capacitance C7 is switched in between the first transmission line 1 and the second transmission line 2 to ground; an eighth capacitor C8 is connected in parallel between the first output terminal 8 and the second output terminal 9.

In one embodiment, the widths of the first transmission line (1), the first coupling line (3) and the second coupling line (4) can be the same or different; the spacing between the first coupling lines (3) of the first transmission line (1) and the spacing between the second coupling lines (4) of the first transmission line (1) can be the same or different;

the widths of the second transmission line (2), the third coupling line (5) and the fourth coupling line (6) can be the same or different; the distance between the third coupling lines (5) of the second transmission line (2) and the distance between the fourth coupling lines (6) of the second transmission line (2) can be the same or different.

In one embodiment, a bias network 10 and an external voltage VCC are introduced between the ground terminals of the first and second coupled lines 3 and 4 and the ground terminals of the third and fourth coupled lines 5 and 6.

One or more embodiments of the present invention may have the following advantages over the prior art:

compared with the traditional Marchand plane balun circuit, the Marchand plane balun circuit has the advantages that the capacitors are connected to the ground in parallel at the grounding positions of the input end and the tail end of the main transmission line, the left coupling line and the right coupling line, so that the length of the transmission line is shortened, and the size of the balun is reduced.

Compared with the traditional Marchand plane balun circuit, the Marchand plane balun circuit has the advantages that 2 MIMs or coupling capacitors are connected in parallel at the original grounding positions of the left coupling line and the right coupling line in an up-and-down symmetrical mode, and the lower electrode plates of the capacitors are connected to the grounding metal surface. The grounding metal surface penetrates through the dielectric substrate through the upper and lower symmetrical grounding through holes and is connected with a metal ground behind the dielectric substrate, and interconnection parasitic inductance is reduced, so that the working frequency of a circuit is improved, the amplitude balance degree and the phase balance degree of the circuit are improved, the Marchand plane balun is in a wide frequency band range of 20-40 GHz, the amplitude unbalance degree of two output ends is less than 0.6dB, and the phase unbalance degree is less than 3 degrees.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic diagram of a conventional three-wire Marchand planar balun circuit;

fig. 2 is a schematic circuit diagram of a Marchand planar balun arrangement according to a first embodiment of the present invention;

FIG. 3 is a schematic diagram of an integrated circuit according to a first embodiment of the present invention;

fig. 4 shows transmission loss and transmission phase shift of two output ports of the Marchand planar balun circuit according to the first embodiment of the present invention;

fig. 5 is a graph of amplitude imbalance and phase imbalance for two ports of a Marchand planar balun circuit in accordance with a first embodiment of the present invention;

fig. 6 is a schematic circuit diagram of a Marchand planar balun arrangement according to a second embodiment of the present invention;

fig. 7 is a schematic circuit configuration diagram of a Marchand planar balun arrangement according to a third embodiment of the present invention;

fig. 8 is a schematic circuit diagram of a Marchand planar balun arrangement according to a fourth embodiment of the present invention;

fig. 9 is a schematic circuit diagram of a Marchand planar balun device according to a fifth embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings.

First embodiment

Fig. 2 is a schematic circuit structure diagram of a Marchand planar balun device according to a first embodiment of the present invention. The present embodiment will be described with reference to fig. 1.

The Marchand planar balun circuit in the embodiment comprises a first transmission line 1 and a second transmission line 2, wherein a first coupling line 3 and a second coupling line 4 are arranged on two sides of the first transmission line 1, a third coupling line 5 and a fourth coupling line 6 are arranged on two sides of the second transmission line 2, one end of the first transmission line 1 is connected with an input end 7, a first capacitor C1 is connected in parallel to the input end 7, namely the inlet of the first transmission line 1, and the first capacitor C1 is grounded; the other end of the first transmission line 1 is connected with the second transmission line 2, and a second capacitor C2 is connected between the other end of the second transmission line and the ground terminal in parallel.

The side of the first coupling line 3 and the second coupling line 4 close to the input end is connected with a third capacitor C3 and a fourth capacitor C4 in parallel to the ground, and the other end of the first coupling line 3 and the other end of the second coupling line 4 are connected with a first output end 8.

One sides of the third coupling line 5 and the fourth coupling line 6 close to the ground end of the second transmission line 2 are connected with a fifth capacitor C5 and a sixth capacitor C6 in parallel to the ground, and the other ends of the third coupling line 5 and the fourth coupling line 6 are connected with the second output end 9.

The integrated circuit layout structure based on the circuit structure is shown in fig. 3, and three metal layers, namely a first metal layer M1, a second metal layer M2 and a third metal layer M3, are arranged above the gallium arsenide substrate from bottom to top. The input signal S is transmitted to the right through the main transmission line of the third metal layer M3.

At the end of the main transmission line of the third metal layer M3, the upper plate of the first capacitor C1 is connected at the first location 12 through the M3-M2 metal pillar, the lower plate of the first capacitor C1 is placed on the first grounding metal G1 of the first metal layer M1, and the first grounding metal G1 penetrates the GaAs dielectric through the two metal vias at the second location 22 and the third location 20 and is connected to the metal ground behind the GaAs dielectric.

The other end of the main transmission line of the third metal layer M3 is connected to the upper plate of the second capacitor C2 at the fourth position 13 through a M3-M2 metal pillar, the lower plate of the second capacitor C2 is placed on the second grounding metal G2 of the first metal layer M1 layer, and the second grounding metal G2 penetrates through the GaAs dielectric through the two metal vias at the fifth position 21 and the sixth position 23 and is connected to the metal ground behind the GaAs dielectric.

The first coupling line in the third metal layer M3 is connected to the upper plate of the third capacitor C3 at the seventh position 14 through a M3-M2 metal pillar, the lower plate of the third capacitor C3 is placed on the first grounding metal G1 of the first metal layer M1 layer, and the first grounding metal G1 penetrates through the GaAs dielectric through the two metal vias at the second position 22 and the third position 20 and is connected to the metal ground behind the GaAs dielectric.

The second coupling line is connected with the upper plate of a fourth capacitor C4 at an eighth position 15 through an M3-M2 metal column, the lower plate of the fourth capacitor C4 is arranged on a first grounding metal G1 on the layer of the first metal layer M1, and the first grounding metal G1 penetrates through the GaAs medium through two metal through holes at the second position 22 and the third position 20 and is connected with a metal ground behind the GaAs medium.

The first coupled line and the second coupled line are interconnected at ends up and down through the elongated metal line of the first metal layer M1 and form a first output terminal of the balun circuit.

The third coupling line is connected with the upper plate of a fifth capacitor C5 at a ninth position 16 through an M3-M2 metal column, the lower plate of the sixth capacitor C5 is placed on a second grounding metal G2 on the layer of the first metal layer M1, and the second grounding metal G2 penetrates through the GaAs medium through two metal through holes at a fifth position 21 and a sixth position 23 and is connected with a metal ground behind the GaAs medium.

The fourth coupling line is connected with the upper plate of a sixth capacitor C6 at a tenth position 17 through an M3-M2 metal column, the lower plate of the sixth capacitor C6 is placed on a second grounding metal G2 on the layer of the first metal layer M1, and the second grounding metal G2 penetrates through the GaAs medium through two metal through holes at a fifth position 21 and a sixth position 23 and is connected with a metal ground behind the GaAs medium.

The third coupled line and the fourth coupled line are interconnected at the ends up and down through the elongated metal line of the first metal layer M1, and form a second output terminal of the balun circuit.

The first grounding metal G1 and the second grounding metal G2 are disposed on the first metal layer M1 and are disposed symmetrically up and down.

The Marchand planar balun circuit of the embodiment increases the grounding of the parallel capacitor at the grounding position of the tail end of the coupling line, and reduces the size of the coupling line. And meanwhile, parallel capacitors are added at the input and tail end positions of the transmission line and grounded, so that the size of the balun transmission line is reduced, and the size of the coupling line is reduced, thereby maintaining the good amplitude balance degree and phase balance degree characteristics of the balun. The transverse length of the Marchand planar balun of the present embodiment can be controlled within 650 μm, and compared with a balun (transverse length 1100um) not adopting the present invention, the size is reduced by 40%, as shown in fig. 4, amplitude and phase characteristics of two output ends of the Marchand planar balun circuit of the present embodiment are shown in fig. 5, in a frequency band range of 20 to 40GHz, amplitude imbalance of the two output ends is less than 0.6dB, and phase imbalance is less than 3 °.

In this embodiment, the first to sixth capacitors may be MIM single-layer capacitors, MIM multilayer capacitors, or interdigital capacitors coupled by transmission line gaps.

The relationship between the parallel capacitance value and the corresponding transmission line can be estimated using the following equation:

C＝1/(4πf Z₀tanθ₀)

the unit is the method (F), F is the working frequency, Z₀Is a characteristic impedance of the transmission line, theta₀Is the propagation phase.

In this embodiment, the transmission line and the coupling line may be microstrip line circuits or coplanar line circuits. When a coplanar line is adopted, the signal ground is distributed on the metal grounds at the upper side and the lower side of the coupling line, and the metal ground can be connected with the metal on the back surface of the dielectric substrate through the through hole or a gold wire.

Second embodiment

As shown in fig. 6, the schematic diagram of the Marchand planar balun circuit according to the second embodiment of the present invention is improved in that a parallel seventh capacitor C7 is connected between the first transmission line 1 and the second transmission line 2 to ground, compared with the first embodiment. Meanwhile, an eighth capacitor C8 is connected in parallel between the first output terminal 8 and the second output terminal 9, and other structures remain the same as in the first embodiment, which is not described herein again.

The effect of adding the seventh capacitor C7 and the eighth capacitor C8 is to effectively improve the balance and bandwidth of the balun circuit, and at the same time, the size of the balun circuit can be further reduced.

Third embodiment

As shown in fig. 7, the schematic diagram of the Marchand planar balun circuit according to the third embodiment of the present invention is improved in that the left and right coupling lines have different line widths, line pitches, or line lengths compared to the second embodiment. That is, the first transmission line 1, the first coupled line 3, and the second coupled line 4 employ a uniform line width, line interval, and line length therebetween, and the second transmission line 2, the third coupled line 5, and the fourth coupled line 6 employ another line width, line interval, and line length therebetween. Other structures remain the same as those in the second embodiment, and are not described again.

Fourth embodiment

As shown in fig. 8, compared with the second embodiment, the Marchand planar balun circuit structure schematic diagram of the fourth embodiment of the present invention is improved by introducing a bias network and a feed between the ground terminals of the left and right coupled lines, that is, introducing a bias network 10 and an external voltage VCC between the ground terminals of the first coupled line 3 and the second coupled line 4 and the ground terminals of the third coupled line 5 and the fourth coupled line 6. The external voltage is directly fed to two output ports of the balun circuit through a direct current path of the balun circuit. Other structures remain the same as those in the second embodiment, and are not described again.

Fifth embodiment

As shown in fig. 9, a schematic diagram of a Marchand planar balun circuit structure according to a fifth embodiment of the present invention is improved over the second embodiment in that a plurality of transmission lines, such as 2 transmission lines, 3 transmission lines, etc., are disposed in each of the first transmission lines and the second transmission lines; the coupling line is also provided with a plurality of lines, such as 3, 4, etc., and is configured according to the number of transmission lines. And two ends of each transmission line are also provided with parallel capacitors and are grounded. And the radio frequency grounding position of each coupling line is also provided with a parallel capacitor and is grounded. The two output ports can be connected with a capacitor in parallel or not.

The above description is only an embodiment of the present invention, and the protection scope of the present invention is not limited thereto, and any person skilled in the art should modify or replace the present invention within the technical specification of the present invention.