• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PURPOSE: A multi-bit phase shifter and a manufacturing method thereof are provided to reduce costs and insertion losses by using a micro electro-mechanical system switch and lower a driving voltage by adopting a DC bias line. CONSTITUTION: A multi-bit phase shifter comprises a first phase shifter and a second phase shifter. The first phase shifter includes a short-circuit stub arranged in parallel with a signal transmitting line, and which has a short-circuit end; an open stub(7) connected in parallel to the short-circuit stub so as to flatten phase characteristics; a micro electro-mechanical system switch(5) arranged in the end of the short-circuit stub, and which controls impedance values; and a DC bias line(6) for lowering the driving voltage of the micro electro-mechanical system switch. The second phase shifter includes a short-circuit stub having a short-circuit end; a micro electro-mechanical system switch arranged in the end of the short-circuit stub, and which controls impedance values; a DC bias line for lowering the driving voltage of the micro electro-mechanical system switch; and an air gap coupler for connecting phase shifters.
    公开号:KR20040072404A
    申请号:KR1020030008878
    申请日:2003-02-12
    公开日:2004-08-18
    发明作者:고영준；박재영
    申请人:엘지전자 주식회사；
    IPC主号:
    专利说明:

    MULTI-BIT PHASE SHIFTER AND MANUFACTURING METHOD THEREOF
    [31] The present invention relates to a phase shifter. In particular, when designing a 5-bit phase shifter for satellite broadcasting and satellite communication, a micro electro mechanical system (hereinafter referred to as MEMS) process technology is applied to reduce insertion loss and cost, and to drive voltage. And a multi-bit phase shifter suitable for minimizing the transition error and a manufacturing method thereof.
    [32] In a communication system, a phased array antenna is essentially used, and a phase shifter for controlling the phase of each antenna in the phased array antenna is an essential part.
    [33] Phase shifters use electronic switches for phase shift control with various delay circuits, and with the advent of Microwave Monolithic Integrated Circuits (MMICs), metal semiconductor field effect transistors (MESFETs) and varactor diodes are used as the switches.
    [34] In recent years, wireless / microwave systems have been designed to meet the requirements of miniaturization, weight reduction, low power, low cost, and integration of devices with improved functions. The development of successors is also in progress.
    [35] Currently, an active phase array system generally used for satellite broadcasting and satellite communication is composed of an antenna, a transceiver, a phase shifter, and an attenuator. The switch used for the phase shifter uses a pin-diode or a field effect transistor. As is known to those skilled in the art, the pin-diode consumes 3 to 10 mW of direct current power in one diode, and the field effect transistor is used as an input. Front-end insertion loss is large.
    [36] Here, the operation method and basic structure of a phase shifter generally used will be described, and the conventional phase shifters will be described.
    [37] A general phase shifter is a device used to acquire a desired phase signal at an output terminal by delaying a phase speed by using a switch, a capacitor, or an inductor.
    [38] FIG. 1A illustrates a circuit for delaying a phase speed by switching signal lines. As shown in FIG. 1A, two lines having different electrical lengths are switched to obtain phase differences between them.
    [39] FIG. 1B appropriately delays the phase velocity of an input signal by using a phase difference between an input signal and a reflected signal.
    [40] Figure 1c increases or decreases the phase velocity using inductors and capacitors, and the transmission line of λ / 4 is used to partially eliminate the reactance mismatch.
    [41] Figure 1d is a method of using the phase difference between the low pass filter and the high pass filter to properly delay the phase speed of the input signal.
    [42] The four methods are general phase delay methods commonly used in phase shifters, and will be applied to the basic operation of the prior art and the present invention described later.
    [43] The structure and features of the 5-bit MMIC phase shifters used in the X band (10-13 GHz, for satellite broadcasting) and the K band (18-20 GHz, for satellite communication) will now be described.
    [44] Figure 2 shows the structure and key delay circuit of the MMIC 5-bit phase shifter for the X band. As shown, it is for 5 bits consisting of 180 °, 45 °, 22.5 °, 11.25 °, and 90 ° phase shifters, and the switch used as seen through the configuration circuit is a field effect transistor (FET).
    [45] First, the 180 ° and 90 ° phase shifters have a structure in which the low pass filter and the high pass filter are connected in parallel as shown in FIG. 1D. When the FET switch of the low pass filter is turned on, the FET switch of the high pass filter is turned off. Pass filter is connected to input and output. On the contrary, when the FET switch of the high pass filter is turned on and connected to the input terminal and the output terminal, the low pass filter is disconnected from the input / output terminal because the FET switch is turned off. Therefore, using the phase difference in both cases, a phase difference of 90/180 ° can be obtained.
    [46] The 45 °, 22.5 °, and 11.25 ° phase shifters are constructed using spiral inductors and FET-switches. The input signal is phase-delayed by the spiral inductor when the switch is turned off, and when the switch is turned on, the input signal proceeds through the shorted switch to the output stage so that no phase delay occurs. Accordingly, a phase difference of 45 / 22.5 / 11.25 ° can be obtained.
    [47] The phase shifter using the MMIC as described above uses a semiconductor device, which makes the manufacturing process complicated. This can be easily seen as the complexity is shown in the figure.
    [48] 3A and 3B are graphs illustrating the phase shifter characteristics of FIG. 2, although they have a uniform phase shift characteristic as in FIG. 3B, but show a large insertion loss of an average of -7.5 dB as in FIG. 3A. This is because the switch used is a FET, which increases the insertion loss. In addition, the semiconductor switch has a complicated manufacturing process, making the process difficult and high manufacturing cost.
    [49] 4A shows the structure and key delay circuit of the MMIC 5-bit phase shifter for the K band. As shown, it is for 5-bits consisting of 180 °, 90 °, 45 °, 22.5 °, and 11.25 ° phase shifters, and consists of three types of phase shifters as can be seen from the configuration circuit. Since a semiconductor circuit is applied, it is complicated as shown.
    [50] FIG. 4B is a 180 ° phase shifter of FIG. 4A, in which the high pass filter and the low pass filter are connected in parallel to set the phase difference to 180 °.
    [51] FIG. 4C is a phase shifter of 90 °, 45 °, and 22.5 ° of FIG. 4A, obtaining a phase difference through a π-network. The configured inductor and capacitor values are set for each bit so that they have a 90 ° / 45 ° / 22.5 ° phase difference, respectively.
    [52] The 11.25 ° phase shifter phase shifts using only capacitors.
    [53] The phase shifter of FIG. 4 uses a HEMT (High Electron Mobility Transistor) as a switch. The insertion loss of the phase shifter represents an average of 5.5 dB or more, and the input / output reflection coefficient is about 10 dB on average.
    [54] Accordingly, the HEMT switch-use phase shifter has improved insertion loss compared to the FET switch-use phase shifter shown in FIG. 2, but is also difficult and expensive because a complicated semiconductor process must be applied.
    [55] As described above, since the phase shifter using the semiconductor switch has a large insertion loss and a complicated process, a phase shifter using a MEMS switch having a small insertion loss and a relatively simple process has been proposed to overcome this problem.
    [56] Fig. 5A is a 4-bit phase shifter using a MEMS switch, and it can be seen that the configuration is simplified as shown. As shown in FIG. 1A, the phase shift method using the delay using the difference in the length of the line is used. It consists of 4-bit phase shifters of °. Each of the lines has a phase difference of 22.5 °, 45 °, 90 °, and 180 ° in electrical length compared to the reference line, and the desired phase delay can be obtained by turning on / off the switch appropriately.
    [57] The phase shifter is designed for a phase passive array system used in direct connection with an antenna, and uses a capacitive loaded MEMS switch as a switch. Therefore, insertion loss is small and the configuration is simple.
    [58] However, as shown in FIG. 5B, the phase characteristics are quite disappointing, and uniform characteristics cannot be obtained for satellite broadcasting (10-13 GHz, X band) or satellite communication (18-20 GHz, K band). The characteristics shown are suitable for use in broadband (DC-20 / 40 GHz) systems and are not applicable to satellite broadcasting or satellite communications.
    [59] In addition, the drive voltage of the switch is very high, such as 98V, it is not easy to apply the system.
    [60] In addition, there is a reflective X-band phase shifter using an RF MEMS switch, but since there is no uniform phase difference (10 ° or more difference), the phase error is large and the driving voltage is also relatively high, such as 30 to 40V.
    [61] As described above, the conventional phase shifter has a complicated manufacturing process in the case of using a semiconductor switch, which has a high process cost and a large insertion loss. There was a problem that the efficiency is low even if not applicable to the phase shifter for satellite communication.
    [62] In view of the above problems, the present invention uses a microelectromechanical system switch to reduce the process cost and insertion loss, and apply a DC bias line to reduce the driving voltage, connect the open stub and the short stub in parallel, and apply an air gap coupler. It is an object of the present invention to provide a multi-bit phase shifter and a method of manufacturing the same to obtain uniform phase characteristics.
    [1] 1A-1D show basic circuits simply showing delay methods of a conventional phase shifter.
    [2] Fig. 2 shows the MMIC 5-bit phase shifter structure and basic driver circuit for the X-band.
    [3] 3A is a graph showing the phase shifter insertion loss of FIG.
    [4] 3B is a graph showing the phase shifter transition characteristics of FIG.
    [5] Figure 4 is a K-band MMIC 5-bit phase shifter structure and basic driver circuit.
    [6] 5 is a graph of the structure and transition characteristics of a 4-bit phase shifter using a MEMS switch.
    [7] Figure 6a is a 5-bit phase shifter structure using the present invention MEMS switch.
    [8] Figure 6b is an actual configuration of Figure 6a.
    [9] 7 is a structure showing a part of the present invention phase shifter.
    [10] 8 is a structure showing another part of the phase shifter of the present invention.
    [11] 9 is a structure of an air gap coupler used in the present invention.
    [12] 10A and 10B are graphs of design characteristics of a phase shifter for satellite broadcasting.
    [13] 10C and 10D are graphs of design characteristics of a phase shifter for satellite communication.
    [14] 11A to 11G are cross-sectional views showing a manufacturing process of a phase shifter using the MEMS switch of the present invention.
    [15] * Description of the symbols for the main parts of the drawings *
    [16] 1: input port 2: output port
    [17] 3: coupler 4: T-junction air bridge
    [18] 5: MEMS switch 6: DC bias line
    [19] 7: Open stub 8: Switch pad
    [20] 10: phase shift 11: input unit
    [21] 12: Output 13: short stub
    [22] 14: switch 20: phase shifter
    [23] 21: input unit 22: output unit
    [24] 23: short stub 24: switch
    [25] 25: Coupler 30: Air gap coupler
    [26] 31: upper metal 32: lower metal
    [27] 41: Substrate 42: The first conductive film
    [28] 43: insulating film 44: resistor
    [29] 45 seed layer 46 electrode
    [30] 47: second conductive film 48: third conductive film
    [63] In order to achieve the above object, the present invention is disposed in parallel with the signal transmission line, the short-circuit stub, the terminal is short-circuited, connected in parallel with the short-circuit stub, and formed on the short-circuit stub, the open stub for flattening the phase characteristics A first phase shifter having a microelectromechanical system (MEMS) switch for controlling an impedance value and a direct current bias line for lowering a driving voltage of the MEMS switch; Shorted short stub, MEMS switch formed at the end of the short stub to control the impedance value, DC bias line for lowering the drive voltage of the MEMS switch, and air for maintaining a stable phase difference phase shifter And a second phase shifter connected by a gap coupler.
    [64] An 11.25 ° phase shifter consisting of one first phase shifter, a 22.5 ° phase shifter consisting of two first phase shifters, a 45 ° phase shifter consisting of two first phase shifters, and the second phase shifter And a 5-bit phase shifter having a 90 ° phase shifter and a 180 ° phase shifter consisting of the second phase shifter.
    [65] In addition, the present invention comprises the steps of forming a first conductive film pattern forming a signal line on a substrate, and forming an insulating film pattern thereon, and then forming a resistor pattern along the DC bias line; Forming an electrode using a seed layer exposed after forming a first photoresist pattern, a seed layer, and a second photoresist pattern on the structure in turn; Removing the second photoresist pattern, etching a portion of the seed layer to be a switch pattern, and removing the others; Forming an air bridge and an air coupler by forming a third photoresist pattern on the structure and forming a conductive layer stacked pattern thereon, and then removing all of the photoresist.
    [66] When described in detail with reference to the accompanying drawings an embodiment of the present invention the phase shifter and its manufacturing method configured as described above are as follows.
    [67] Figure 6a shows a structure of a 5-bit phase shifter for satellite broadcasting and satellite communication using the MEMS switch of the present invention. As shown, the signal applied to the input terminal 1 is output to the output terminal 2 through the 180 ° / 90 ° phase shifter after the 11.25 ° / 22.5 ° / 45 ° phase shifter.
    [68] As shown, the present invention differs in the structure of a 11.25 ° / 22.5 ° / 45 ° phase shifter that is a multiple of 11.25 ° and a 180 ° / 90 ° phase shifter that is a multiple of 90 °. However, the phase shifters cause the phase difference of the reflected wave by using the capacitance as shown in FIG. 1C.
    [69] In the 11.25 ° phase shifter, an open stub 7 is positioned on the upper side and a short stub is disposed on the lower side of the signal line connected to the input terminal 1. The connection of the stubs consists of a T-junction air bridge 4. The air bridge 4 is used to connect grounds to form a common ground. The open stub 7 results in a linear phase characteristic and wider bandwidth. Then, the MEMS switch 5 is formed at the end of the short stub, and the DC bias line 6 is folded in a concave-convex shape in order to lower the switch driving voltage. The DC bias line 6 is a resistive signal line, one side of which is connected to a corresponding MEMS switch 5 and the other side of which is connected to a switch pad 8 for applying a switch control signal (see FIG. The switch signal line is disconnected, but this may differ depending on the design).
    [70] The control voltage is applied to the switch pad 8 or the switch signal line to drive the MEMS switch 5 via a DC bias line, and the open stub 7 acts as a capacitor to delay the input signal. . This phase difference is determined by the capacitance on / off ratio by the operation of the MEMS switch 5.
    [71] After appropriately adjusting the stub lengths and the length of the DC bias line of the formed phase shifter, the 22.5 ° / 45 ° phase shifters are formed by overlapping them.
    [72] The 180 ° phase shifter and the 90 ° phase shifter also use a short stub and a MEMS switch (5) to adjust the capacitance on / off ratio to create a phase difference.The phase shifters, excluding the open stub, are moved to the air gap coupler (3). Connect. The 180 ° / 90 ° phase shifters have a stable phase difference by the air gap coupler 3.
    [73] FIG. 6B is a photograph of a device actually configuring FIG. 6A, and parts to be described are enlarged. As shown in the figure, a simple structure facilitates design and implementation.
    [74] As described above, the embodiment of the present invention uses a MEMS switch to reduce the insertion loss and simplify the process, and the phase characteristics are good because the stubs are used, and the phase difference is maintained stably because the air gap coupler is used. In addition, since the DC bias line is formed of a resistor, the MEMS switch driving voltage is lowered to 15 to 20V.
    [75] FIG. 7 shows a basic structure of an 11.25 ° / 22.5 ° / 45 ° phase shifter, and a shorting stub 13 having a short-circuited part in parallel to a transmission line between the input part 11 and the output part 12 as shown in FIG. ) Is formed, and the MEMS switch 14 is connected to the end thereof. By the operation of the MEMS switch 14, the short stub 13 operates as a capacitor to delay the phase of the input signal. The operation method of delaying the phase by adding an inductor or a capacitor in parallel to the transmission line has been mentioned in FIG. 1C, where the shorting stub 13 is used as a substitute for the capacitor. Since the impedance value seen from the terminated stub is determined by the on / off ratio of the MEMS switch 14, the change of the impedance value connected in parallel changes the phase of the input signal to 11.25 ° / 22.5 ° / 45 °. .
    [76] 8 shows the basic structure of the 180 ° / 90 ° phase shifter and is composed of two phase shifters, which are connected by an air coupler 25. A basic configuration of each phase shifter is that short circuit stubs 23 are connected in parallel, and MEMS switches 24 are connected to ends of the short stubs 23, as shown in FIG. As shown in FIG. 7, the impedance value seen from the shorted stub is determined by the on / off ratio of the MEMS switches 14. In this embodiment, the MEMS switches 24 are turned on / off by the same control signal.
    [77] 9 shows an air coupler 30 used for a 180 ° / 90 ° phase shifter, consisting of a lower metal 32 and an upper metal 31, which are spaced apart and these structures are diagonally symmetrical. It is formed. Each metal part is connected with a short stub. It is known to those skilled in the art that the air coupler 30 as described above improves the phase characteristic.
    [78] 10A to 10B are graphs showing characteristics of the X band (10 to 13 GHz) 5-bit phase shifter designed according to the present invention. As shown, the insertion loss shows an average of 4.5 dB and the minimum reflection loss of 10 dB. Even with the phase characteristics, it can be seen that the improvement effect according to the present invention is clear since the phase error becomes less than 3 degrees in the phase characteristics of 11.25 degrees. Therefore, the phase shifter of the present invention has excellent performance for satellite broadcasting.
    [79] 10B to 10C are graphs showing characteristics of a K band (18 to 20 GHz) 5-bit phase shifter designed according to the present invention. As shown, an insertion loss exhibits an average of 4.5 dB and a minimum reflection loss of less than 10 dB. . Even with the phase characteristics, it can be seen that the improvement effect according to the present invention is clear since the phase error becomes less than 3 degrees in the phase characteristics of 11.25 degrees. Therefore, the phase shifter of the present invention has excellent performance for satellite communication.
    [80] In addition, the MEMS switch used in the present invention is driven at a low voltage of 15 ~ 20V, it is also noteworthy that the practical application is advantageous.
    [81] Now, a method of manufacturing the present invention phase shifter will be described.
    [82] 11A to 11G are cross-sectional views of a manufacturing process of the phase shifter according to the present invention. As shown in FIG. 11A to 11G, a first conductive film 42 pattern forming a signal line is formed on a substrate 41 and an insulating film 43 pattern is formed thereon. Forming a resistor 44 pattern along the direct current bias line (FIG. 11A); Forming a first photoresist pattern PR1 on the structure and forming a seed layer 45 thereon (FIG. 11B); After forming the second photoresist pattern PR2 identical to the first photoresist pattern PR1 on the seed layer 45, forming the electrode 46 using the seed layer 45 (FIG. 11c); Removing the second photoresist pattern PR2 and then etching a portion of the seed layer 45 using a chrome mask MK to remove a portion of the seed layer 45 in a switch pattern (FIG. 11D); Forming a third photoresist pattern PR3 on an air bridge and air coupler formation region in the upper portion of the structure (FIG. 11E); Forming a second conductive film 47 and a third conductive film 48 on the structure in turn, and then patterning the conductive laminated films 47 and 48 according to the air bridge and air coupler structures (FIG. 11F) and ; The first photoresist pattern PR1 and the third photoresist pattern PR3 formed on the structure are removed using a step (FIG. 11G).
    [83] This will be explained in more detail.
    [84] First, as shown in FIG. 11A, Cr / Pt is deposited and patterned on the substrate 41 to form a pattern of the first conductive film 42 that forms a signal line and to protect the first conductive film 42. An AlN insulating film 43 pattern is formed on the pattern. Then, TaN or Nichrome is formed and patterned according to a DC bias line to form a resistor 44 pattern.
    [85] Next, as shown in FIG. 11B, the first photoresist pattern PR1 is formed on the structure to form a basic molding for forming an electrode, and then an Au / Cr seed layer 45 is formed thereon. This is because Au to form the electrode is formed through the plating process. Part of the seed layer 45 is then used as a hinge pattern for the MEMS switch.
    [86] Next, as shown in FIG. 11C, a second photoresist pattern PR2 identical to the first photoresist pattern PR1 is formed on the seed layer 45 to form photoresist molding for forming the electrode 46. Next, the Au electrode 46 is formed using the molding structure and the seed layer 45.
    [87] Next, as shown in FIG. 11D, after removing the second photoresist pattern PR2, a portion of the seed layer 45 may be removed from the MEMS switch while protecting the electrode 46 by applying a chrome mask MK. Form a hinge pattern and remove the rest.
    [88] Next, as shown in FIG. 11E, the third photoresist pattern PR3 is formed in the air bridge and air coupler formation regions in the upper portion of the structure. The pattern PR3 exposes a portion of the electrodes to which the air bridge and the air coupler are to be connected.
    [89] Next, as shown in FIG. 11F, the second conductive film 47 and the third conductive film 48 are sequentially formed on the structure, and the conductive laminated films 47 and 48 are formed according to the air bridge and air coupler structures. Pattern). The second conductive film 47 and the third conductive film 48 are formed of different materials, and preferably contain Au.
    [90] Next, as shown in FIG. 11G, the first photoresist pattern PR1 and the third photoresist pattern PR3 formed on the structure are removed, so that the hinge structure 45 of the MEMS switch has a lower signal line 42. Secure an area that can be operated by
    [91] As described above, it can be seen that the MEMS switch structure can be formed in a fairly simple process compared to the general semiconductor switch manufacturing process.
    [92] As described above, the phase shifter of the present invention uses a microelectromechanical system switch to lower the process cost and insertion loss, and applies a DC bias line to lower the driving voltage, connects an open stub and a short stub in parallel, and applies an air gap coupler. In order to obtain a uniform phase characteristic, the performance of a phase shifter suitable for use in satellite broadcasting and satellite communication bands can be greatly improved, but the price can be lowered.
    权利要求:
    Claims (6)
    [1" claim-type="Currently amended] A microelectromechanical system (MEMS) disposed in parallel with a signal transmission line and having a short end stub connected in parallel with the shorting stub, an open stub for parallelizing the short circuit stub, and formed at the end of the short stub to control an impedance value. A first phase shifter having a switch and a direct current bias line for lowering a driving voltage of the MEMS switch; Shorted short stub, MEMS switch formed at the end of the short stub to control the impedance value, DC bias line for lowering the drive voltage of the MEMS switch, and air for maintaining a stable phase difference phase shifter And a second phase shifter connected by a gap coupler.
    [2" claim-type="Currently amended] 2. The multi-bit phase shifter of claim 1, wherein the first phase shifters constitute one or more of the phase shifters that are connected to generate a phase difference in multiples of 11.25 °.
    [3" claim-type="Currently amended] 2. The multi-bit phase shifter as claimed in claim 1, wherein the second phase shifter constitutes phase shifters which adjust the microelectromechanical system switches to generate a phase difference in multiples of 90 degrees.
    [4" claim-type="Currently amended] 2. The multi-bit phase shifter of claim 1, further comprising air bridges for forming a common ground between grounds of the first phase shifter and the second phase shifter.
    [5" claim-type="Currently amended] 2. The multi-bit phase shifter of claim 1, wherein the multi-bit phase shifter comprises a 11.25 ° phase shifter consisting of one first phase shifter, a 22.5 ° phase shifter consisting of two first phase shifters, and 45 of two first phase shifters. A 5-bit phase shifter comprising a phase shifter, a 90 ° phase shifter consisting of the second phase shifter, and a 180 ° phase shifter consisting of the second phase shifter.
    [6" claim-type="Currently amended] Forming a first conductive film pattern forming a signal line on the substrate, forming an insulating film pattern thereon, and forming a resistor pattern according to a DC bias line; Forming an electrode using a seed layer exposed after forming a first photoresist pattern, a seed layer, and a second photoresist pattern on the structure in turn; Removing the second photoresist pattern, etching a portion of the seed layer to be a switch pattern, and removing the others; Forming a third photoresist pattern on the structure and forming a conductive layer stacked pattern thereon to form an air bridge and an air coupler, and then removing all of the photoresist; Manufacturing method.
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    同族专利:
    公开号 | 公开日
    EP1447875A1|2004-08-18|
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    US20040155729A1|2004-08-12|
    JP2004364251A|2004-12-24|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2003-02-12|Application filed by 엘지전자 주식회사
    2003-02-12|Priority to KR1020030008878A
    2004-08-18|Publication of KR20040072404A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1020030008878A|KR20040072404A|2003-02-12|2003-02-12|Multi-bit phase shifter and manufacturing method thereof|
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