CN101673865B - Balun Fabricated Using Integrated Passive Components Process - Google Patents

Abstract

A balun manufactured by using an integrated passive component process comprises a substrate, a first coplanar spiral structure body and a second coplanar spiral structure body. One end of the first left coil at the innermost circle of the first coplanar spiral structure body is electrically connected with the first right coil at the innermost circle through the first bridging part. The two ends of the first coplanar spiral structure body are respectively and electrically connected with the first left coil and the first right coil of the outermost ring. One end of the second left coil at the innermost circle of the second coplanar spiral structure is electrically connected with the second right coil at the innermost circle through the second bridging part. And two ends of the second coplanar spiral structure are respectively and electrically connected with the second left coil and the second right coil of the outermost ring. The first left coil and the second left coil are arranged in a staggered mode, and the first right coil and the second right coil are arranged in a staggered mode.

Description

Balun Fabricated Using Integrated Passive Components Process

technical field

The present invention relates to a balun circuit, and more particularly to a balun circuit manufactured using an Integrated Passive Device (IPD) process.

Background technique

Generally speaking, when the antenna in the communication device receives the wireless signal, the single-port electrical signal output by the antenna is output to a balun. The balun will convert the single-port electrical signal into a dual-port electrical signal, and output it to a radio frequency (Radio Frequency, RF) transceiver (Transceiver) for processing.

A current balun is achieved by a low temperature co-fired ceramic (LTCC) process. However, the balun manufactured by this LTCC process must first be electrically connected to a substrate by Surface-Mount Technology (SMT) before it can be electrically connected to the RF transceiver chip on the substrate. In this way, the area for configuring the balun produced by the LTCC process and the area for configuring the radio frequency transceiver chip must be reserved on the base material at the same time, so that the required area of the base material increases and occupies a larger space of the communication device. Therefore, how to reduce the area of the required substrate to save the internal space of the communication device is one of the directions that the industry is working on.

Contents of the invention

The invention relates to a balun manufactured by an integrated passive component process, which can be directly configured on a radio frequency transceiver chip, thereby reducing the required substrate area and saving the internal space of the communication device.

According to the present invention, a balun manufactured using an Integrated Passive Device (IPD) process is proposed, including a substrate, a first coplanar helical structure and a second coplanar helical structure. The first coplanar spiral structure has a first end, a second end, a plurality of first left coils, a plurality of first right coils and a first bridging portion. One end of the innermost first left coil is electrically connected to the innermost first right coil via the first bridging portion. The first end is electrically connected to the first left coil of the outermost circle, and the second end is electrically connected to the first right coil of the outermost circle. The second coplanar spiral structure has a third end, a fourth end, a plurality of second left coils, a plurality of second right coils and a second bridging portion. One end of the innermost second left coil is electrically connected to the innermost second right coil via the second bridging portion. The third end is electrically connected to the second left coil of the outermost circle, and the fourth end is electrically connected to the second right coil of the outermost circle. The first left coils are alternately arranged with the second left coils, and the first right coils are alternately arranged with the second right coils.

In order to make the above-mentioned content of the present invention more obvious and understandable, the preferred embodiments are specifically cited below, together with the accompanying drawings, and are described in detail as follows:

Description of drawings

FIG. 1 is a schematic diagram of a balun.

FIG. 2 is an equivalent circuit diagram of the balun shown in FIG. 1 .

FIG. 3A is a schematic structural diagram of a balun manufactured using an integrated passive device process according to an embodiment of the present invention.

Fig. 3B is a cross-sectional view of the balun along the section line 3B-3B' in Fig. 3A.

FIG. 4A is a schematic diagram showing an example of the configuration relationship between the IPD and the radio frequency transceiver chip having the structure of the balun in this embodiment.

FIG. 4B is a schematic diagram showing another example of the configuration relationship between the IPD and the radio frequency transceiver chip having the structure of the balun in this embodiment.

FIG. 5 is a graph showing the simulation results of reflection loss and insertion loss of the balun of this embodiment.

FIG. 6 is a graph showing the simulation results of the amplitude difference and phase difference of two output signals of the balun of this embodiment.

Description of main component symbols:

100: Balun

102, 104: transmission line

110: unbalanced port

112, 114: balanced ports

300: Balun

302: Substrate

312: first end

314: second end

316: The first connecting line

318: Second connection line

320(1), 320(2), 320(3): first left coil

322(1), 322(2), 322(3): First right coil

324: The first bridging department

332: third end

334: Fourth end

336: The third connecting line

338: The fourth connecting line

340(1), 340(2), 340(3): second left coil

342(1), 342(2), 342(3): Second right coil

344: Second bridging part

352: The first wiring layer

354: Second wiring layer

402, 408: Integrate passive components

404, 410: RF transceiver chip

406, 412: Substrate

602, 604: relationship curve

Detailed ways

Please refer to FIG. 1 , which shows a schematic diagram of a balun. The balun includes transmission lines 102 and 104, and capacitors C1, C2 and C3. One end of the transmission line 102 is electrically connected to an unbalanced port (Unbalance Port) 110, and the other end of the transmission line 102 is grounded. One end of the transmission line 104 is electrically connected to the balance port (BalancePort) 112 and the capacitor C2, and the other end of the transmission line 104 is electrically connected to the balance port 114 and the capacitor C3.

Please refer to FIG. 2 , which shows an equivalent circuit diagram of the balun in FIG. 1 . The transmission line 102 can be equivalent to the inductor L1, and the transmission line 104 can be equivalent to the inductor L2. For AC signals, the midpoint of the transmission line 104 can be regarded as a virtual ground, so the center of the inductance L2 of the equivalent transmission line 104 is equivalent to the ground. Through the coupling effect between the inductors L1 and L2 , the single-ended signal input from the unbalanced port 110 can be converted into a differential signal output from the balanced ports 112 and 114 . The signals output from the balanced ports 112 and 114 have substantially the same amplitude, but the phases of the two signals are substantially 180 degrees different.

The above capacitors C1, C2 and C3 are used to adjust the bandwidth of the passband, adjust the insertion loss, or perform impedance transformation.

Please refer to FIG. 3A and FIG. 3B at the same time. FIG. 3A is a schematic structural diagram of a balun manufactured using an integrated passive device (Integrated Passive Device, IPD) process according to an embodiment of the present invention, and FIG. 3B is a schematic diagram of FIG. 3A , a cross-sectional view of the balun 300 along the section line 3B-3B'. The balun 300 includes a substrate 302 (shown in FIG. 3B ), a first coplanar helical structure, and a second coplanar helical structure. The first coplanar helical structure has a first end 312 , a second end 314 , a plurality of first left coils, a plurality of first right coils and a first bridge portion 324 .

The plurality of first left coils include, for example, left coils 320(1), 320(2) and 320(3). The plurality of first right coils include, for example, right coils 322(1), 322(2) and 322(3).

In the first coplanar spiral structure, one end of the innermost first left coil 320 ( 3 ) is electrically connected to the innermost first right coil 322 ( 3 ) via the first bridging portion 324 . The first end 312 is electrically connected to the outermost first left coil 320(1), and the second end 314 is electrically connected to the outermost first right coil 322(1).

The second coplanar spiral structure has a third end 332 , a fourth end 334 , a plurality of second left coils, a plurality of second right coils and a second bridge portion 344 . The plurality of second left coils include, for example, second left coils 340(1), 340(2) and 340(3). The plurality of second right coils include, for example, second right coils 342(1), 342(2) and 342(3).

In the second coplanar spiral structure, one end of the innermost second left coil 340 ( 3 ) is electrically connected to the innermost second right coil 342 ( 3 ) via the second bridging portion 344 . The third terminal 332 is electrically connected to the outermost second left coil 340(1), and the fourth terminal 334 is electrically connected to the outermost second right coil 342(1).

The first left coils are interlaced with the second left coils, and the first right coils are interlaced with the second right coils. For example, the first left coils and the second left coils are represented by the second left coil 340(1), the first left coil 320(1), the second left coil 340(2), the first left coil 320(2 ), the second left coil 340(3), and the first left coil 320(3) are arranged from outside to inside. These first right coils and these second right coils are represented by the second right coil 342(1), the first right coil 322(1), the second right coil 342(2), the first right coil 322(2), the The order of the second right coil 342(3) and the first right coil 322(3) is arranged from outside to inside.

Preferably, the first left coils 320(1)-320(3) and the second left coils 340(1)-340(3) are arranged at equal intervals. The first right coils 322(1) to 322(3) and the second right coils 342(1) to 342(3) are arranged at equal intervals. The first end 312 is electrically connected to the outermost first left coil 320(1) through the connecting wire 316, and the second end 314 is electrically connected to the outermost first right coil 322(1) through the connecting wire 318. . The third end 332 is electrically connected to the outermost second left coil 340 ( 1 ) through the connecting wire 336 , and the fourth end 334 is electrically connected to the outermost second right coil 342 ( 1 ) through the connecting wire 338 .

Furthermore, please refer to FIG. 3B , the substrate 302 has a first wiring layer 352 and a second wiring layer 354 . In the first coplanar spiral structure, the first connecting line 316, the second connecting line 318, the first left coils 320(1)-320(3) and the first right coils 340(1)-340(3 ) is disposed on the first wiring layer 352 , and the first bridging portion 324 is disposed on the second wiring layer 354 . The first left coil 320 ( 3 ) is electrically connected to the first bridge portion 324 through the through hole 360 , and the first bridge portion 324 is electrically connected to the first right coil 322 ( 3 ) through the through hole 362 . In this way, the first left coil 320 ( 3 ) is electrically connected to the first right coil 322 ( 3 ) via the first bridge portion 324 .

In the second coplanar spiral structure, the first connecting line 336, the second connecting line 338, the second left coils 340(1)-340(3), the second right coils 342(1)-342(3) It is arranged on the first wiring layer 352 . The second bridge portion 344 is disposed on the second wiring layer 354 .

Preferably, the sum of the lengths of the first left coils 320(1)-320(3) is substantially equal to the sum of the lengths of the first right coils 322(1)-322(3). The sum of the lengths of the second left coils 340(1)-340(3) is substantially equal to the sum of the lengths of the second right coils 342(1)-342(3). In this way, when the first end 312 is used as the unbalanced port 110, the second end 314 is grounded, and the third end 332 and the fourth end 334 are respectively used as the balanced ports 112 and 114, the third end 332 and the fourth end 334 will be able to output Two signals of substantially the same amplitude but substantially 180 degrees out of phase.

As shown in FIG. 3A , the first terminal 312 , the third terminal 332 and the fourth terminal 334 are electrically connected to the capacitors C1 , C2 and C3 respectively.

In the balun 300 of this embodiment, the coupling between the first coplanar helical structure and the second coplanar helical structure is achieved by edge coupling. This way can make the coupling mechanism less affected by the external reference ground voltage, and can achieve a better coupling effect.

In addition, since the balun of this embodiment only needs two wiring layers, it is particularly suitable for manufacturing by IPD technology, that is, it is manufactured by thin film technology. The balun manufactured by the IPD process has the advantages that the line width and line spacing of the coil can be precisely controlled, and the line width and line spacing can be made smaller than the line width and line spacing of the traditional LTCC process. . Therefore, compared with the balun manufactured by the LTCC process, the balun manufactured by the IPD process of this embodiment has the advantage of reducing the layout area.

Please refer to FIG. 4A , which is a schematic diagram showing an example of the configuration relationship between the IPD 402 and the radio frequency transceiver chip 404 having the structure of the balun 300 of the present embodiment. The IPD 402 is configured on the substrate 406, and the RF transceiver chip 404 can be configured on the IPD 402. The radio frequency transceiver chip 404 is electrically connected to the substrate 406 through a plurality of vias 405 in the IPD 402 , for example. In this way, compared with the practice that the balun manufactured by the traditional LTCC process must be directly arranged on the substrate to be electrically connected with the radio frequency transceiver chip arranged in other regions of the substrate, the IPD 402 of this embodiment can achieve The advantage of saving the substrate 406 area.

Please refer to FIG. 4B , which shows a schematic diagram of another example of the configuration relationship between the IPD 408 and the radio frequency transceiver chip 410 having the structure of the balun in this embodiment. The IPD 408 is disposed on the substrate 412, and the RF transceiver chip 410 can be disposed in the space below the IPD 408. This configuration also has the advantage of saving the area of the substrate 412 .

Please refer to FIG. 5 , which shows the simulation results of the return loss and insertion loss of the balun of this embodiment. The first port 312 serving as the unbalanced port 110 is used as an input port, and the third port 332 and the fourth port 334 serving as the balanced ports 112 and 114 are used as output ports to perform a simulation of a two-port balun. From the relationship curve 502 of reflection loss and the relationship curve 504 of insertion loss in FIG. 5 , it can be seen that the reflection loss is about -42dB and the insertion loss is about -1dB around a frequency of 2.5 GHz. It can be seen from this that the balun 300 of this embodiment can indeed complete the signal conversion action at a frequency near 2.5 GHz.

Please refer to FIG. 6 , which shows a simulation result diagram of the amplitude difference (Amplitude imbalance) and the phase difference (Phase imbalance) of the two output signals of the balun of this embodiment. From the relationship curve 602 of the amplitude difference between the output signals of the third terminal 332 and the fourth terminal 334 , it can be seen that the amplitude difference between the two is between 0.25 and −0.37 at frequencies between 2 GHz and 3 GHz. From the relationship curve 604 of the phase difference between the output signals of the third terminal 332 and the fourth terminal 334 , it can be seen that the phase difference between the two is about 182.5 degrees. It can be seen from this that the balun of this embodiment can indeed meet the requirements of the general balun that the amplitudes of the two output signals are substantially the same and the phase difference is substantially 180 degrees.

Although the balun 100 with the capacitors C1 , C2 and C3 is taken as an example for illustration, the balun 100 may not need the capacitors C1 , C2 and C3 .

The balun manufactured by using the IPD process of the present invention can achieve the advantages of reducing the layout area and saving the area of the substrate, and can make the communication device used more light, thin and short, so it has good market competitiveness.

To sum up, although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (5)

1. A balun manufactured using an integrated passive component process, comprising: A substrate having a first wiring layer and a second wiring layer; A first coplanar spiral structure has a first end, a second end, several first left coils, several first right coils, and a first bridging portion, the innermost circle of the first left coil One end is electrically connected to the first right coil of the innermost circle through the first bridging portion, the first end is electrically connected to the first left coil of the outermost circle, and the second end is electrically connected to the second coil of the outermost circle. A right coil is electrically connected, and the second end is grounded; A second coplanar spiral structure has a third end, a fourth end, several second left coils, several second right coils, and a second bridging portion, the innermost circle of the second left coil One end is electrically connected to the second right coil of the innermost circle through the second bridging portion, the third end is electrically connected to the second left coil of the outermost circle, and the fourth end is electrically connected to the second left coil of the outermost circle. Two right coils are electrically connected; Wherein, the first left coils and the second left coils are arranged on the first wiring layer and intersect each other, the first right coils and the second right coils are arranged on the first wiring layer and intersect each other, the first bridging portion and the second bridging portion are disposed on the second wiring layer; and Wherein, the first terminal, the third terminal and the fourth terminal are respectively electrically connected to the corresponding first capacitor, the second capacitor and the third capacitor. 2. The balun as claimed in claim 1, wherein the first left coils and the second left coils are equally spaced. 3. The balun as claimed in claim 1, wherein the first right coils and the second right coils are equally spaced. 4. The balun as claimed in claim 1, wherein the sum of the lengths of the first left coils is substantially equal to the sum of the lengths of the first right coils. 5. The balun as claimed in claim 1, wherein the sum of the lengths of the second left coils is substantially equal to the sum of the lengths of the second right coils.

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