CN1783579A - Miniature Multilayer Balanced-to-Unbalanced Signal Converter - Google Patents

Abstract

The invention provides a miniature multi-layer balance-to-unbalance signal converter. The converter includes a pair of lines having capacitive elements, at least one segment of broadside coupled lines connected in series to an unbalanced port and two balanced ports via a pair of transmission lines. Each of the plurality of sections of the wide area coupling lines is provided with a first coupling line and a second coupling line. The ground link is located between the two second coupling lines at the center and connected to a ground plane. By means of the multilayer structure and this ground connection, the converter of the invention can be manufactured with five conductor layers. This not only greatly reduces the size of the converter, but also enhances the stability of the converter. The difference in measured return loss and signal magnitude versus frequency response and phase difference illustrate that the converter of the present invention has good impedance matching.

Description

Miniature Multilayer Balanced-to-Unbalanced Signal Converter

technical field

The present invention relates to a balance-to-unbalance signal converter (balance-to-unbalance transformer, Balun) used in wireless communication, especially a miniaturized multi-layer balance-to-unbalance signal converter.

Background technique

The balanced-to-unbalanced signal converter is one of the common passive components in wireless communication systems. Its function is to convert an unbalanced signal (unbalanced signal) in the wireless communication transceiver module into a pair of balanced signals with the same size and a difference of 180 degrees. Differential mode signal (balanced differential signal), of course, its circuit characteristics and vice versa, can reduce the interference of common mode noise (commonmode noise) by the transmission of differential mode signal, so in radio frequency (radio frequency, RF) transceiver, power amplifier ( Balanced to unbalanced signal converters are often seen in the circuit design of poweramplifier, PA), antenna (antenna) and mixer (mixer).

There are many types of balanced-to-unbalanced signal converters, which can generally be divided into three types: lumped-type, coil-type and distributed-type. The lumped balanced-to-unbalanced signal converter uses lumped capacitors and inductors for impedance matching and produces 180-degree phase difference and equal signal size balance. This kind of balanced-to-unbalanced signal converter is characterized by its small size, so it is very lightweight, but the disadvantage is that the operating bandwidth is small, and it is not easy to maintain the balance of the phase difference and signal size between the two signals.

Wire-wound balanced-to-unbalanced signal converters are most widely used in lower frequency bands and ultra high frequency (UHF) frequency bands. But the main disadvantage is that there will be too much loss when the application exceeds the UHF frequency band, and the degree of miniaturization has reached the limit.

Distributed balanced-to-unbalanced signal converters are also divided into 180-degree-hybrid and Marchand. The 180-degree-hybrid type is often used in the microwave frequency band and has a good frequency response. However, when applied to radio frequency, the frequency is between 200MHz and several GHz. Since it is composed of several quarter-wavelength transmission lines, the size is often too large, and it is difficult to reduce it by a large amount even by means of meanders. its area. In another technique, a power splitter and a pair of transmission lines with different lengths to generate a phase difference of 180 degrees are used to reduce its area. However, there is still the problem of oversizing.

US Patent 6,661,306 discloses a refined lumped balanced-to-unbalanced signal converter. This converter has a dual highpass (highpass) and lowpass (lowpass) arrangement (layout). As shown in FIG. 1 , the converter 100 is composed of lumped elements arranged overlappingly. According to the frequency band (band), the converter 100 adjusts the value of capacitance and inductance, and then uses the metal transmission line and metal electrode on the substrate to produce a plate with equivalent capacitance and inductance. ) and spiral (spiral) structure.

The advantage of this design is that it can be combined into multiple passive components Shaped circuit architecture. Furthermore, the converter and the filter circuit are integrated to form a filter with an unbalanced signal output at one end and a balanced signal output at the other end. However, its disadvantage is that it requires multiple passive components. If one of the more sensitive passive components is slightly changed due to manufacturing process errors or material characteristics, it will cause a large change in the original functional characteristics of the entire circuit, and requires a large Design space for this circuit design.

US Patent No. 6,483,415 discloses a multilayer LC resonance balanced-to-unbalanced signal converter. As shown in FIG. 2A , the converter 200 utilizes a capacitor 201 and a plurality of coupled lines 202 a - 202 d to form an LC resonance structure, and only has one side adjustable transmission line and capacitance.

Referring again to the balanced-to-unbalanced signal converter shown in FIG. 2B . The converter 210 utilizes at least two capacitors 211-212 and a plurality of coupling lines 213-214 to form an equivalent LC resonance structure. Couple the unbalanced signal input from the input port to the balanced signal, and then output it from the balanced output port. The length of the coupled inductor and the area of the capacitor are related to the design of the transmission frequency band. The advantage is that the capacitance and inductance are integrated in a three-dimensional stack structure, which can greatly reduce the circuit design area. The disadvantage is that this design architecture uses half wavelength to achieve the effect equivalent to the quarter wavelength grounding of the center of the coupled line, and even more than 6 to 8 metal layers need to be applied. Therefore, it is only applicable to the substrate manufacturing process that can be made in multiple layers, and the precise alignment of the manufacturing process may easily affect the component manufacturing result.

US Patent No. 5,497,137 discloses a five-layer balanced-to-unbalanced signal converter. As shown in FIG. 2C , the converter 220 includes a first strip line 222 , a second strip line 226 , and a third strip line 228 . The first stripe line 222 is composed of a first portion 224a and a second portion 224b, which are respectively coupled to the second stripe line 226 and the third stripe line 228 . The disadvantage of this converter 220 is the same as that of the above-mentioned converters. The half-wavelength is used to achieve the effect equivalent to the quarter-wavelength grounding of the center of the coupled line.

Contents of the invention

The present invention is to overcome the disadvantages of the above-mentioned conventional balanced-to-unbalanced signal converter. Its main purpose is to provide a miniature multilayer balanced-to-unbalanced signal converter, which has an equivalent circuit with a ground connection and a pair of capacitive elements, which have a capacitor The polarity element is located at both ends of the coupled line connected to the balance I/O port. The equivalent circuit includes a first group of at least one coupled wire, a second group of at least one coupled wire, first and second transmission lines, a pair of capacitive elements, and a ground connection. Through the multi-layer structure, the size of the converter is greatly reduced. Furthermore, this converter can be implemented with a small number of layers. Therefore, the manufacturing process of the converter is simple, the cost is reduced (reduced cost), and the productivity (improvedyield rate) can be improved.

According to the invention, the pair of capacitive elements and coupled lines each have a symmetrical structure with respect to a center. In a preferred embodiment of the present invention, these at least one section of coupled lines are connected in series through the first and second transmission lines, wherein the coupled lines connected to the same side of the unbalanced input and output ports are connected in series through the first transmission line, and connected to The coupled lines to the same side of the balanced input and output ports are connected in series via the second transmission line. The ground connection is defined between the first group of coupled lines and the second group of coupled lines, and is connected to the same side as the balanced input and output ports. The ground link is connected to ground. Each transmission line has two ends. One end of the first transmission line is connected to the ground, and the other end is connected to the unbalanced input and output port. Two ends of the second transmission line are respectively connected to two balanced input and output ports.

In practical applications, the ground connection can be formed by via holes or the same layer of metal. The pair has a capacitive element which can be a capacitor, or a vertical coupling electrode (vertical coupling electrode), or a horizontal (horizontal) coupling line.

For reaching above-mentioned object, the present invention provides a kind of miniature multi-layer balance to unbalanced signal converter, comprises: an unbalanced port; First and second balanced port; First and second have capacitive element, each There are first and second terminals with a capacitive element, the first end with a capacitive element is connected to the unbalanced port, the second end with a capacitive element is grounded, and the second end with a capacitive element is connected to the unbalanced port. two ends of the element are respectively connected to the first and second balanced ports; first and second transmission lines, each transmission line has first and second ends, and the first end of the first transmission line is connected to the unbalanced port, The second end of the first transmission line is connected to the ground, and the two ends of the second transmission line are respectively connected to the first and second balanced ports; at least one wide-face coupled line, each wide-face coupled line is equipped with a first and the second coupled line, the first coupled line of each wide-face coupled line is connected in series between the two ends of the first transmission line, and the second coupled line of each wide-faced coupled line is connected between the two ends of the second transmission line ends in series together, and; a ground link, with first and second ends, the first end connected to the second transmission line between the two second coupled lines in the center, and the second end connected to ground .

Wherein, the first and second capacitive elements are capacitors; the first and second capacitive elements are vertical coupling electrodes; the first and second capacitive elements are horizontal coupling lines; the converter is composed of Formed in a symmetrical multilayer structure with respect to a central point; the ground connection is connected to ground via a metal plate or through-hole.

Wherein, the multilayer structure has at least five vertically stacked conductor layers, and includes: a first conductor layer with a major surface formed by the unbalanced port, the first and second balanced Formed by the port, the first coupled line of the at least one wide-face coupled line, and the first and second transmission lines; a second conductor layer with a main surface, the main surface is formed by the at least one wide-faced A second coupled line of coupled lines, the ground connection, and at least two through holes are formed; a third conductor layer is provided with a major surface formed by the first electrode cap having a capacitive element, and at least A through hole is formed; a fourth conductor layer is provided with a major surface formed by the second first electrode cap having a capacitive element and at least one through hole; and a fifth conductor layer is prepared A major surface is formed by the second electrode cap having a capacitive element, and at least one perforation.

Wherein, the through hole on the second conductor layer is used to connect the second coupled line of the at least one wide-faced coupled line to the first and second balanced ports, and to connect the ground connection to the ground; the third conductor The perforation on the layer is used to connect the electrode cap with the first capacitive element to the unbalanced port; the perforation on the fourth and fifth conductor layers is used to connect the first and second electrode cap to the unbalanced port respectively; The first and second balanced ports, or to the second and first balanced ports.

By adopting the present invention, not only the size of the converter device is greatly reduced, but also the stability of the converter device is enhanced. In this way, precise adjustment and higher pass rate can be obtained. In addition, the converter device can be applied to various substrates, including dielectric substrates, ceramics substrates, nano-material substrates, and integrated circuit (IC) substrates. The converter device can also be used in manufacturing ICs, Micro-Electro-Mechanical-Systems (MEMS), passive components, or nami-technologies. The converter device can also be applied in the field of wireless communication. The above and other objectives and advantages of the present invention will be described in detail below with reference to the following drawings, detailed description of the embodiments and claims.

Description of drawings

Figure 1 is a traditional lumped balanced-to-unbalanced signal converter.

FIG. 2A is a traditional multilayer LC resonant balanced-to-unbalanced signal converter.

FIG. 2B is another conventional multilayer LC resonant balanced-to-unbalanced signal converter.

FIG. 2C is a traditional five-layer balanced-to-unbalanced signal converter.

FIG. 3A is an equivalent circuit diagram of a preferred embodiment of a miniature multilayer balanced-to-unbalanced signal converter according to the present invention.

FIG. 3B is a circuit diagram extended from FIG. 3A including multi-section wide-face coupled lines.

FIG. 4 is a schematic diagram of a multilayer device structure of a balanced-to-unbalanced signal converter having the equivalent circuit diagram of FIG. 3A .

FIG. 5A is a response diagram of simulated amplitude versus frequency of the balanced-to-unbalanced signal converter of the present invention.

FIG. 5B illustrates the simulation results of the frequency response of the signal magnitude difference and phase difference of the balanced-to-unbalanced signal converter of the present invention.

Wherein, the reference signs are explained as follows:

100 converters

200 converter 201 capacitor

202a-202d coupling line

210 Converter Capacitor 211-212

213-214 coupling line

220 converter 222 first stripe line

226 second stripe line 228 third stripe line

224a Part I 224b Part II

300 equivalent circuit 301a, 301b have capacitive elements

302, 303 wide surface coupling line 304 grounding connection

306a, 306b balanced input and output ports 312, the first transmission line

313 second transmission line 333, 322 ground

305 unbalanced input and output ports 302a, 303a first coupling line

302b, 303b second coupling line 308 connection point

The middle section on the left of 31i The middle section on the right of 31j

311 leftmost section 310 rightmost section

310a, 311a first coupling line 310b, 311b second coupling line

401~405 first~fifth conductor layer 407a~407d perforation

414～416 electrode cap

Detailed ways

FIG. 3A is an equivalent circuit diagram of a preferred embodiment of a miniature multilayer balanced-to-unbalanced signal converter according to the present invention. The equivalent circuit 300 includes a pair of capacitive elements 301a and 301b, a broad coupled line 302, another broad coupled line 303, a pair of transmission lines 312 and 313, and a ground connection 304, the pair has a capacitive The neutral elements 301a and 301b are connected to the balanced and unbalanced input and output ports on the same side, respectively, and the ground connection 304 is connected to the two balanced input and output ports 306a and 306b on the same side.

As shown in FIG. 3A, each capacitive element is provided with two terminals. One end with the capacitive element 301 a is connected to a ground 333 , and the other end is connected to the unbalanced input/output port 305 . Two ends of the capacitive element 301b are respectively connected to two balanced input and output ports 306a and 306b. This section of the wide coupling line 302 also includes a first coupling line 302a and a second coupling line 302b. The wide coupled lines 303 in this section further include a first coupled line 303a and a second coupled line 303b. The first coupling line 302a of the wide-area coupling line 302 and the first coupling line 303a of the wide-area coupling line 303 are connected in series via the first transmission line 312 . Similarly, the second coupling line 302b of the broadside coupling line 302 and the second coupling line 303b of the broadside coupling line 303 are connected in series via the second transmission line 313 . Each transmission line has two ends. One end of the first transmission line 312 is connected to the ground 333 , and the other end is connected to the unbalanced input/output port 305 . Two ends of the second transmission line 313 are respectively connected to the two balanced input and output ports 306a and 306b. The ground connection 304 is on the same side as the connection to the balanced input and output ports. One end of the ground link 304 is connected to a connection point 308 between the two second coupling lines 302 b and 303 b, and the other end is connected to the ground 322 .

In practical applications, the ground connection can be formed by vias or the same layer of metal. Capacitive elements can be capacitors, or vertical coupling electrodes, or horizontal coupling lines. The broadside coupled lines in this preferred embodiment have a symmetrical structure with respect to the central point. The circuit in this preferred embodiment may further include multiple sections of wide-faced coupling lines, such that the central point extends parallel to both sides, as shown in FIG. 3B .

It can be seen from FIG. 3B that a multi-section wide-surface coupling line extends from the left and right sides of the central point, and is respectively connected to the wide-surface coupling lines 302 and 303 . Each section of the wide-face coupling line also includes a first coupling line and a second coupling line. Each first coupling line above the middle section 31i on the left is connected in series. Each second coupled line below the left middle section 31i is also connected in series. The middle section 31j on the right is also connected in series in a similar manner. The first coupled line 311 a of the leftmost segment 311 is connected to the unbalanced I/O port 305 via the first transmission line 312 , and its second coupled line 311 b is connected to the balanced I/O port 306 a via the second transmission line 313 . The first coupled line 310 a of the rightmost segment 310 is connected to the ground 333 via the first transmission line 312 , and the second coupled line 310 b thereof is connected to the balanced I/O port 306 b via the second transmission line 313 .

As mentioned earlier, through the multi-layer structure, the size of the converter can be greatly reduced. Furthermore, this converter can be implemented with a small number of layers. This can be illustrated in Figure 4. FIG. 4 illustrates a multilayer device structure of a balanced-to-unbalanced signal converter having the equivalent circuit of FIG. 3A.

The balanced-to-unbalanced signal converter in FIG. 4 includes five conductor layers 401-405, which are vertically stacked. An unbalanced I/O port 305, a ground 333, two balanced I/O ports 306a and 306b, and two transmission lines 312 and 313 (not shown) are formed on the main surface of the first conductor layer 401 . The two second coupling lines 302 b and 303 b and the ground connection 304 are fabricated on the second conductor layer 402 . The third conductor layer 403 implements a metal-insulator-metal (MIM) electrode cap 414 with the capacitive element 301a. Since the end with the capacitive element 301a is connected to the ground 333, only one conductor layer is sufficient to implement the electrode cap with the capacitive element. In contrast, the fourth and fifth conductor layers 404 and 405 implement metal-insulator-metal electrode caps 415 and 416 with the capacitive element 301b.

In the multi-layer device structure, the conductive layer is drilled with a plurality of through holes to provide connections between electrical components formed on the conductive layer. For example, the through hole 407a on the third conductor layer 403 is to provide a connection between the fourth conductor layer 404 and the second conductor layer 402 to the first conductor layer 401 to form a capacitive element 301b, a second coupling line 302b, and the electrical connection between the balanced input and output port 306a. Similarly, the through hole 407b on the fourth conductor layer 404 is to provide a connection between the fifth conductor layer 405 and the second conductor layer 402 to the first conductor layer 401 to form a capacitive element 301b, a second coupling The electrical connection between the line 302b and the balanced input and output port 306b. The through hole 407c on the second conductor layer 402 is to provide a connection between the third conductor layer 403 and the first conductor layer 401 to form a connection with the capacitive element 301a, the first coupling line 302a, and the unbalanced input and output port 305. electrical connection between. The vias 407d in the second conductor layer 402 are provided for all ground connections in different conductor layers.

According to the present invention, different capacitance values can be used to achieve the target achievement of the balanced-to-unbalanced signal converter within the operating frequency range. FIG. 5A is a diagram of the simulated amplitude to frequency response (amplitude to frequency response) of the balanced-to-unbalanced signal converter of the present invention. The horizontal axis is the operating frequency of the converter, in GHz. The vertical axis shows the return loss at a single end, and the amplitudes of differential mode and common mode in dB. The return loss at a single terminal refers to the reflected impedance of the input signal from the unbalanced input port 305, and its value should be less than -10dB in the designed frequency range (2.34-2.54GHz). The amplitude value of the differential mode is the transmission energy (energy) from the differential mode signal input from the balanced input port to the unbalanced port, and its value should be at least -2dB in the operating frequency range. The amplitude value of the common mode is the transmitted energy from the common mode signal input from the balanced input port to the unbalanced port, and its value should be less than -10dB in the operating frequency range.

It can be seen from Fig. 5A that the value of the return loss is less than -10dB. The transmitted energy of the differential mode signal is considerably higher than -2dB. The transmitted energy of the common mode signal is considerably lower than -10dB. This means that the balanced input port receives most of the energy of the incoming signal, and this energy is also distributed evenly. Therefore, the balanced-to-unbalanced signal converter of the present invention has good impedance matching.

FIG. 5B illustrates the simulation results of the frequency response of the signal magnitude difference and phase difference of the balanced-to-unbalanced signal converter of the present invention. The horizontal axis is the operating frequency of the converter, in GHz. The vertical axis is respectively signal magnitude difference (in dB) and phase difference (in degree). The signal size difference is the signal size difference between the two output and output ports transmitted from the unbalanced input port to the balanced output and output port, and must be less than 2dB. The phase difference value is the phase difference value of the two I/O ports transmitted from the unbalanced input port to the two balanced I/O ports, and must be kept at about 180°±10°. It can be seen from FIG. 5B that the signal magnitude difference of the balanced-to-unbalanced signal converter of the present invention is between 0.25dB and 0.75dB, and the phase difference is between 178° and 182°.

Compared with the conventional vertically coupled balanced-to-unbalanced signal converter, at least 6-8 conductor layers are usually required to manufacture the converter. However, the miniature multi-layer balanced-to-unbalanced signal converter of the present invention only needs 5 conductor layers to manufacture, because the ground connection is added in the coupling line connected to the ground. This not only greatly reduces the size of the converter device, but also enhances the stability of the converter device. In this way, precise adjustment and higher pass rate can be obtained. In addition, the converter device can be applied to various substrates, including dielectric substrates, ceramics substrates, nano-material substrates, and integrated circuit (IC) substrates. The converter device can also be used in manufacturing ICs, Micro-Electro-Mechanical-Systems (MEMS), passive components, or nami-technologies. The converter device can also be applied in the field of wireless communication.

However, the above descriptions are only preferred embodiments of the present invention, and should not limit the implementation scope of the present invention. That is, all equivalent changes and modifications made according to the claims of the present invention should still fall within the scope covered by the patent of the present invention.

Claims (10)

1. A miniature multilayer balanced-to-unbalanced signal converter, comprising: an unbalanced port; first and second balanced ports; first and second capacitive elements each having first and second terminals, the first end of the first capacitive element connected to the unbalanced port, the first capacitive element The second end of the second terminal is grounded, and the two ends of the second capacitive element are respectively connected to the first and second balanced ports; First and second transmission lines, each transmission line has first and second ends, the first end of the first transmission line is connected to the unbalanced port, the second end of the first transmission line is grounded, and the two ends of the second transmission line terminals are respectively connected to the first and second balanced ports; At least one section of broadside coupled lines, each section of wideplane coupled lines is provided with first and second coupled lines, the first coupled lines of each section of widened coupled lines are connected in series between the two ends of the first transmission line, The second coupled lines of each section of broad-face coupled lines are connected in series between the two ends of the second transmission line, and; A ground link has first and second ends, the first end is connected to the second transmission line between the central two second coupling lines, and the second end is grounded. 2. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 1, wherein the first and second capacitive elements are capacitors. 3. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 1, wherein the first and second capacitive elements are vertical coupling electrodes. 4. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 1, wherein the first and second capacitive elements are horizontal coupling lines. 5. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 1, wherein the converter is formed by a symmetrical multi-layer structure with respect to a center point. 6. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 1, wherein the ground connection is grounded through a metal sheet or a through hole. 7. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 5, wherein the multi-layer structure has at least five vertically stacked conductor layers, and comprises: a first conductor layer having a major surface composed of the unbalanced port, the first and second balanced ports, the first coupled line of the at least one broadside coupled line, and the first and formed by the second transmission line; a second conductor layer having a major surface formed by the second coupled line of the at least one broadside coupled line, the ground connection, and at least two through-holes; a third conductor layer having a major surface formed by an electrode cap having the first capacitive element, and at least one perforation; a fourth conductor layer having a major surface formed by the second first electrode cap having a capacitive element, and at least one perforation; and A fifth conductor layer has a major surface formed by the second electrode cap having the second capacitive element and at least one perforation. 8. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 7, wherein the through hole on the second conductor layer is used to connect the second coupled line of the at least one wide-faced coupled line to the first One and a second balanced port, and connecting the ground connection to the ground. 9. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 7, wherein the through hole on the third conductor layer is used to connect the first electrode cap with a capacitive element to the unbalanced port . 10. The miniature multi-layer balanced-to-unbalanced signal converter as claimed in claim 7, wherein the through-holes on the fourth and fifth conductor layers are respectively used to connect the first and second electrode caps to the first and the second balanced port, or to the second and the first balanced port.

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