A high power handling single pole double throw switch

Abstract

The present invention discloses a single-pole double-throw switch with high power capacity, which relates to the field of microwave millimeter wave technology. The symmetrically arranged first switch branch and the second switch branch both include a series branch and a five-way parallel branch in series. The two adjacent parallel branches are connected in series through a microstrip transmission line. The input end of the series branch is connected to the radio frequency input end. The five-way parallel branch includes two switch parallel branches and three cascaded switch series-parallel branches connected in series between the two switch parallel branches. The input of one switch parallel branch is connected to the output end of the series branch, and the output of the other switch parallel branch is connected to the radio frequency output end. Each level of series-parallel branch includes two field effect tube series units symmetrically arranged and connected at the same point. Each level of series-parallel branch is equivalent to four field effect tubes connected in series, which can improve the anti-burning ability of the switch, and improve the isolation degree while improving the anti-burning ability of the switch.

Description

Technical Field

[0001] The invention relates to the technical field of microwave and millimeter waves, and in particular to a single-pole double-throw switch with high power capacity. Background Art

[0002] A single-pole double-throw switch is a device used to select the RF signal path. It is widely used in the communications field for receiving and transmitting switches, frequency band selection or antenna diversity switches. As a key circuit in phased array systems, radar / base station signal transceiver systems and other scenarios, the single-pole double-throw switch is generally required to have high isolation, high power capacity and strong anti-burning ability.

[0003] The traditional single-pole double-throw switch only connects one branch in parallel in the direction of signal transmission. The parallel branch switch can increase the power capacity but reduce its isolation. Under the same peak voltage, adding a parallel branch switch can reduce its total resistance, increase its power capacity and reduce the deterioration of its isolation. Therefore, how to make the switch have high power capacity, strong anti-burning ability and ensure its isolation is a problem that needs to be solved. Summary of the invention

[0004] The object of the present invention is to provide a single-pole double-throw switch with high power capacity, which is cascaded with five parallel branches, wherein the five parallel branches include two switch parallel branches and three cascaded switch series-parallel branches connected in series between the two switch parallel branches. The number of series switches in the parallel direction is increased by the three cascaded switch series-parallel branches, thereby improving the switch's anti-burning ability.

[0005] In order to achieve the above objectives, the following solutions are proposed:

[0006] The present invention provides a single-pole double-throw switch with high power capacity, comprising a first switch branch and a second switch branch which are symmetrically arranged, wherein the first switch branch and the second switch branch both comprise a series branch and five series parallel branches, two adjacent parallel branches are connected in series via a microstrip transmission line, an input end of the series branch is connected to a radio frequency input end, the five parallel branches comprise two switch parallel branches and three cascaded switch series-parallel branches which are connected in series between the two switch parallel branches, wherein the input of one switch parallel branch is connected to the output end of the series branch, and the output of another switch parallel branch is connected to the radio frequency output end.

[0007] In some specific embodiments, the five parallel branches include a first switch parallel branch, a first switch series-parallel branch, a second switch series-parallel branch, a third switch series-parallel branch and a second switch parallel branch, the first switch parallel branch and the first switch series-parallel branch are connected through a first microstrip transmission line, the first switch series-parallel branch and the second switch series-parallel branch are connected through a second microstrip transmission line, the second switch series-parallel branch and the third switch series-parallel branch are connected through a third microstrip transmission line, the third switch series-parallel branch and the second switch parallel branch are connected through a fourth microstrip transmission line, and the second switch parallel branch and the RF output end are connected through a fifth microstrip transmission line, wherein the circuit topology structures of the first switch series-parallel branch, the second switch series-parallel branch and the third switch series-parallel branch are all the same.

[0008] In some specific embodiments, the first switch series-parallel branch, the second switch series-parallel branch and the third switch series-parallel branch each include two field effect transistor series units that are symmetrically arranged and connected in parallel at the same point, and each field effect transistor series unit includes two field effect transistors connected in series.

[0009] In some specific implementation schemes, the first microstrip transmission line, the second microstrip transmission line, the third microstrip transmission line, and the fourth microstrip transmission line use 1 / 4 wavelength transmission lines for impedance transformation.

[0010] In some specific embodiments, the length of the first microstrip transmission line is greater than the length of the second microstrip transmission line, the length of the second microstrip transmission line is less than the length of the third microstrip transmission line, the length of the third microstrip transmission line is greater than the length of the fourth microstrip transmission line, and the length of the fourth microstrip transmission line is greater than the length of the fifth microstrip transmission line.

[0011] In some specific embodiments, the third microstrip transmission line is equivalent to an inductor.

[0012] In some specific embodiments, the series branch includes a first field effect transistor and a second field effect transistor, the source of the first field effect transistor is connected in series with the drain of the second field effect transistor, the drain of the first field effect transistor of the first switch branch and the drain of the first field effect transistor of the second switch branch are connected together and then connected to the RF input terminal through a transmission line, and the source of the second field effect transistor is connected to the first switch parallel branch.

[0013] In some specific embodiments, the first switch parallel branch includes a third field effect transistor and a fourth field effect transistor connected in series, the source of the third field effect transistor is connected in series with the drain of the fourth field effect transistor, the drain of the third field effect transistor is connected to the source of the second field effect transistor, and the source of the fourth field effect transistor is grounded.

[0014] In some specific embodiments, the second switch parallel branch includes a fifth field effect transistor, the drain of the fifth field effect transistor is connected in parallel between the fourth microstrip transmission line and the fifth microstrip transmission line, and the source of the fifth field effect transistor is connected in series with a resistor to ground.

[0015] The inventive concept of this application is:

[0016] Existing, such as Figure 1 As shown, a single-pole double-throw switch generally uses six cascaded stacked field effect tube units to increase the power capacity of the switch. Each level of stacked field effect tube units uses four-finger field effect tubes. In this structure, although the power capacity of each path is improved, since each level of stacked field effect tube units is only connected in parallel on one side of the transmission line direction, its isolation will be attenuated.

[0017] Therefore, in order to maintain the improvement of the anti-burning ability while keeping the isolation unchanged, a three-stage switch series-parallel branch is added to the parallel branch in the present application, and each stage of the series-parallel branch includes two field effect tube series units symmetrically arranged and connected to the same point in the direction of the transmission line, and each field effect tube series unit includes two field effect tubes connected in series. Since each stage of the series-parallel branch is equivalent to two pairs of switch groups in parallel, and each pair of switch groups is connected in series with two field effect tubes, the anti-burning ability of the switch can be improved, and the isolation can be improved by symmetrically arranging the field effect tube series units in parallel on both sides of the same point on the transmission line. This is because when the two field effect tubes are connected in series and then in parallel, the isolation of the entire switch system will be attenuated to a considerable extent. Therefore, in order to maintain the improvement of the anti-burning ability while keeping the isolation unchanged, it is necessary to add a field effect tube series unit with the same parallel symmetrical structure on the other side of the transmission line. In this way, the two field effect tube series units of each series-parallel switch branch are symmetrically arranged to improve the isolation. In addition, microstrip transmission lines are used to connect the parallel branches, and the five microstrip transmission lines are designed with long and short intervals to achieve impedance transformation.

[0018] The present invention has the beneficial effects:

[0019] The present invention provides a high-power capacity single-pole double-throw switch, which is formed by adding a three-stage switch series-parallel branch in a parallel branch, wherein each stage of the series-parallel branch includes two field effect tube series units symmetrically arranged and connected at the same point in the direction of the transmission line, and each field effect tube series unit includes two field effect tubes connected in series. The field effect tube series units are symmetrically arranged in parallel on both sides of the same point on the transmission line, so that the isolation can be improved. Each stage of the series-parallel branch is equivalent to two pairs of switch groups connected in parallel, and each pair of switch groups is connected in series with two field effect tubes, which can improve the anti-burning ability of the switch, and improve the isolation while improving the anti-burning ability of the switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the topology of a conventional single-pole double-throw switch circuit in the prior art;

[0021] Figure 2 A schematic diagram of a topology of a single-pole double-throw switch circuit with high power capacity provided by an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of a circuit topology of a first switch branch provided in an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of a circuit topology of a switch series-parallel branch provided by an embodiment of the present invention;

[0024] Figure 5 Based on Figure 2 The obtained circuit layout simulation diagram;

[0025] Figure 6 This is a schematic diagram of power capacity comparison provided by the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0028] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0029] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0030] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0031] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0032] Existing, such as Figure 1 As shown, the existing single-pole double-throw switch includes a power divider and two single-pole double-throw switches, each single-pole double-throw switch includes 6 identical stacked field effect tube units, and two adjacent stacked field effect tube units are connected by a transmission line TL Con One end of the power divider is connected as the signal input end to the input, and the other end is connected to the single-pole double-throw switch in two ways and then connected to output 1 and output 2 respectively. Each branch includes 6 serial field effect tube units connected in sequence and connected in parallel on one side of the transmission line. Each stacked field effect tube unit includes two field effect tubes, wherein the source S of one field effect tube is connected to the branch, the drain D is connected to the source S of another field effect tube, and the drain D of the other field effect tube is grounded. Although the power capacity of this traditional single-pole double-throw switch has been improved, there is still room for improvement. In view of this, the present application proposes the following scheme:

[0033] Example 1

[0034] like Figure 2 As shown, this embodiment provides a single-pole double-throw switch with high power capacity, including a first switch branch and a second switch branch that are symmetrically arranged, the first switch branch and the second switch branch both include a series branch and five series parallel branches, two adjacent parallel branches are connected in series through a microstrip transmission line, the input end of the series branch is connected to the radio frequency input end RFC, the five parallel branches include two switch parallel branches and three cascaded switch series-parallel branches connected in series between the two switch parallel branches, the input of one switch parallel branch is connected to the output end of the series branch, and the output of the other switch parallel branch is connected to the radio frequency output ends RF1 and RF2.

[0035] Since the topological structures and parameters of the first switch branch and the second switch branch are the same, this embodiment takes the first switch branch as an example. The specific structure of the first switch branch is as follows: Figure 3 As shown:

[0036] The five parallel branches include a first switch parallel branch, a first switch series-parallel branch, a second switch series-parallel branch, a third switch series-parallel branch and a second switch parallel branch. The first switch parallel branch is connected to the first switch series-parallel branch through a first microstrip transmission line TL1, the first switch series-parallel branch and the second switch series-parallel branch are connected through a second microstrip transmission line TL2, the second switch series-parallel branch and the third switch series-parallel branch are connected through a third microstrip transmission line TL3, the third switch series-parallel branch and the second switch parallel branch are connected through a fourth microstrip transmission line TL4, and the second switch parallel branch is connected to the radio frequency output terminal RF1 through a fifth microstrip transmission line TL5.

[0037] Among them, for impedance transformation, the first microstrip transmission line TL1, the second microstrip transmission line TL2, the third microstrip transmission line TL3, and the fourth microstrip transmission line TL4 use 1 / 4 wavelength transmission lines for impedance transformation. The lengths of the first microstrip transmission line TL1, the second microstrip transmission line TL2, the third microstrip transmission line TL3, the fourth microstrip transmission line TL4, and the fifth microstrip transmission line TL5 are set in a long-short interval, that is, the length of the first microstrip transmission line TL1 is greater than the length of the second microstrip transmission line TL2, the length of the second microstrip transmission line TL2 is less than the length of the third microstrip transmission line TL3, the length of the third microstrip transmission line TL3 is greater than the length of the fourth microstrip transmission line TL4, and the length of the fourth microstrip transmission line TL4 is greater than the length of the fifth microstrip transmission line TL5. And in order to ensure isolation, the third microstrip transmission line TL3 is equivalent to an inductor.

[0038] The topological structures of the first switch series-parallel branch, the second switch series-parallel branch and the third switch series-parallel branch are all the same, such as Figure 4 As shown, it includes two field effect tube series units that are symmetrically arranged and connected in parallel at the same point, and each field effect tube series unit includes a field effect tube M6 and a field effect tube M7 connected in series. The drain of the field effect tube M6 is connected in series with the source of the field effect tube M7, the source of the field effect tube M6 is grounded, and the drain of the field effect tube M7 is connected in parallel to the microstrip transmission line. The gates of the field effect tubes M6 and M7 are connected to the control terminal through gate resistors and are controlled by voltage. The gate widths of the field effect tubes M6 and M7 are 4*50um.

[0039] The series branch includes a first field effect transistor M1 and a second field effect transistor M2, the source of the first field effect transistor M1 is connected in series with the drain of the second field effect transistor M2, the drain of the first field effect transistor M1 of the first switch branch and the drain of the first field effect transistor M1 of the second switch branch are connected together and then connected to the radio frequency input terminal RFC through a transmission line, and the source of the second field effect transistor M2 is connected to the first switch parallel branch. The gates of the first field effect transistor M1 and the second field effect transistor M2 are connected to the control terminal through a gate resistor.

[0040] Specifically, the first switch parallel branch includes a third field effect transistor M3 and a fourth field effect transistor M4 connected in series, the source of the third field effect transistor M3 is connected in series with the drain of the fourth field effect transistor M4, the drain of the third field effect transistor M3 is connected to the source of the second field effect transistor M2, and the source of the fourth field effect transistor M4 is grounded. The gates of the third field effect transistor M3 and the fourth field effect transistor M4 are connected to the control terminal through a gate resistor. The second switch parallel branch includes a fifth field effect transistor M5, the drain of the fifth field effect transistor M5 is connected in parallel between the fourth microstrip transmission line TL4 and the fifth microstrip transmission line TL5, and the source of the fifth field effect transistor M5 is connected in series with a resistor to ground.

[0041] In order to better illustrate the design process of the single-pole double-throw switch of this application, taking the design of 0.5W (27dBm) power as an example, all field effect tubes in this application use 0.5umD-type pHEMT (pseudomorphic high electron mobility transistor) in Sanan GaAs 0.25um process, and the parameters of different pHEMTs are as follows:

[0042] Table 1 pHEMT parameters

[0043]

[0044] When the selected field effect tube has a pinch-off voltage / threshold voltage VP / Vth = -1V, -VP = -1, a gate-drain avalanche voltage BV = 18V, and a maximum current = 525mA / mm, the working principle of the field effect tube in the parallel structure and the series structure is:

[0045] 1. When the field effect tube forms a series branch, the field effect tube has low impedance, is in the on state, and the signal is transmitted; the field effect tube has high impedance, is in the off state, and the signal is cut off. In the on state, the peak current passing through the field effect tube is:

[0046] (1)

[0047] Among them, P max Indicates the maximum power, I dmax Represents the maximum current, ZL represents the load impedance. When the microstrip line width of the 1 / 4 wavelength transmission line is W=15um, according to this process, the current that can flow through the double-layer metal is 20mA / um, then the maximum current that can flow through the microstrip line of W=15um is 15*20=300mA.

[0048] The calculated impedance of W=15um is 84Ω, which is substituted into the above formula (1):

[0049] I max =0.133A, then the maximum total gate width current I required by the FET max / Maximum drain current Id max=253um, and 126.5um is required for one side, and the current is 66.5mA. Based on this, it can be known that the gate width of the field effect transistors M1 and M2 in the series branch should be at least 253um. When the field effect transistor with a gate width of 6*60um=360um is used and the gate-source voltage (VGS) = 0V, the saturation current Idss=97mA>66.5mA meets the requirements.

[0050] 2. In the parallel structure, the field effect tube has low impedance, which is the off state, and the signal is cut off; the field effect tube has high impedance, which is the on state, and the signal is transmitted;

[0051] For parallel branches:

[0052] (2)

[0053] Among them, the field effect tube is in Z 0 When the impedance is high, the switch is closed, the signal is cut off, the gate-drain avalanche voltage is VB, and the pinch-off voltage is VP. According to the parameters in the table above, assuming that there are N field effect transistors in series in a parallel branch, then:

[0054] (3)

[0055] When N=1, P=1.72W=32.36dBm, when N=2, P=6.88W=38.38dBm, connecting two field effect transistors in series in the parallel branch can fully meet the power capacity requirements. For the field effect transistors M6 and M7 of the field effect transistor series unit connected in parallel on the transmission line, the gate width of the field effect transistors M6 and M7 is 4*50um.

[0056] Understanding the working principle of the above-mentioned field effect tube in the switch circuit, in this application, the length of the microstrip transmission line between each level of parallel branches is first designed to be one short and one long. In order to change the impedance, the microstrip transmission line adopts a 1 / 4 wavelength transmission line. In this way, two adjacent parallel branches are connected in series with a 1 / 4 wavelength transmission line. When the switch is controlled by a negative voltage, the switch is high impedance on this branch. After the impedance transformation of the 1 / 4 wavelength transmission line, the impedance will become low impedance. At this time, the signal transmission of this branch is through, while the other branch is the opposite. When the switch is controlled by 0 voltage, the switch is low impedance on this branch. After the impedance transformation of the 1 / 4 wavelength transmission line, the impedance will become high impedance. At this time, the signal transmission of this branch is off.

[0057] In this embodiment, in order to improve the anti-burning ability of the switch in the parallel branch, two sets of field effect tubes are connected in series in the field effect tube series unit on each series-parallel branch in the middle. The field effect tube M7 is located at the parallel position of the two sets of field effect tube series units. A 1 / 4 wavelength transmission line is used to add the parallel field effect tube M7. When the bias voltage of the turned-off switch is 0V, its equivalent impedance is set to Z L , the impedance transformation is carried out through the 1 / 4 wavelength transmission line. The input end is high impedance. At this time, the RF signal is open circuit, and its input impedance is Z i n =Z 2 0 / Z L For each FET series unit, FET M6 and FET M7 are connected in series and then in parallel to the transmission line, so that its impedance Z L This is equivalent to twice that of a single field effect tube, thus reducing the off-state input impedance Z in , connecting two field effect tubes in series and then in parallel can increase the burnout resistance by 4 times compared to connecting a single field effect tube in parallel.

[0058] When two field effect transistors are connected in series and then in parallel on one side of the transmission line, the isolation of the entire switch system will be attenuated to a considerable extent. Therefore, in order to maintain the isolation while improving the anti-burnout capability, it is necessary to add a field effect transistor series unit with the same parallel symmetrical structure on the other side of the transmission line. In this way, the two field effect transistor series units of each series-parallel switch branch are symmetrically arranged to improve the isolation.

[0059] According to the above topological structure, the design is as follows Figure 5 The layout structure shown in the figure is simulated according to the layout structure. Figure 6 As shown, it can be seen that the input P-1=28dBm of the single-pole double-throw switch proposed in the present application is greater than the input P-1=25dBm of the traditional switch structure, the entire switch P-1 is significantly improved, and the power capacity is significantly improved.

[0060] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A single-pole double-throw switch with high power capacity, characterized in that: It includes a symmetrically arranged first switch branch and a second switch branch, each of the first switch branch and the second switch branch includes a series branch and five series parallel branches, two adjacent parallel branches are connected in series via a microstrip transmission line, the input end of the series branch is connected to the radio frequency input end, the five parallel branches include two switch parallel branches and three cascaded switch series-parallel branches connected in series between the two switch parallel branches, the input of one switch parallel branch is connected to the output end of the series branch, and the output of another switch parallel branch is connected to the radio frequency output end; The five parallel branches include a first switch parallel branch, a first switch series-parallel branch, a second switch series-parallel branch, a third switch series-parallel branch, and a second switch parallel branch which are sequentially connected in series, the first switch parallel branch and the first switch series-parallel branch are connected via a first microstrip transmission line, the first switch series-parallel branch and the second switch series-parallel branch are connected via a second microstrip transmission line, the second switch series-parallel branch and the third switch series-parallel branch are connected via a third microstrip transmission line, the third switch series-parallel branch and the second switch parallel branch are connected via a fourth microstrip transmission line, and the second switch parallel branch is connected to a radio frequency output terminal via a fifth microstrip transmission line, wherein the circuit topology structures of the first switch series-parallel branch, the second switch series-parallel branch, and the third switch series-parallel branch are all the same; The first switch series-parallel branch, the second switch series-parallel branch and the third switch series-parallel branch each include two field effect tube series units that are symmetrically arranged and connected in parallel at the same point, and each field effect tube series unit includes two field effect tubes connected in series.

2. A single-pole double-throw switch with high power capacity according to claim 1, characterized in that: The first microstrip transmission line, the second microstrip transmission line, the third microstrip transmission line and the fourth microstrip transmission line use 1 / 4 wavelength transmission lines for impedance transformation.

3. A single-pole double-throw switch with high power capacity according to claim 2, characterized in that: The length of the first microstrip transmission line is greater than that of the second microstrip transmission line, the length of the second microstrip transmission line is less than that of the third microstrip transmission line, the length of the third microstrip transmission line is greater than that of the fourth microstrip transmission line, and the length of the fourth microstrip transmission line is greater than that of the fifth microstrip transmission line.

4. A single-pole double-throw switch with high power capacity according to claim 2, characterized in that: The third microstrip transmission line is equivalent to an inductor.

5. A single-pole double-throw switch with high power capacity according to claim 1, characterized in that: The series branch includes a first field effect transistor and a second field effect transistor, the source of the first field effect transistor is connected in series with the drain of the second field effect transistor, the drain of the first field effect transistor of the first switch branch and the drain of the first field effect transistor of the second switch branch are connected together and then connected to the radio frequency input end through a transmission line, and the source of the second field effect transistor is connected to the first switch parallel branch.

6. A single-pole double-throw switch with high power capacity according to claim 1, characterized in that: The first switch parallel branch includes a third field effect tube and a fourth field effect tube connected in series, the source of the third field effect tube is connected in series with the drain of the fourth field effect tube, the drain of the third field effect tube is connected to the source of the second field effect tube, and the source of the fourth field effect tube is grounded.

7. A single-pole double-throw switch with high power capacity according to claim 1, characterized in that: The second switch parallel branch includes a fifth field effect tube, the drain of the fifth field effect tube is connected in parallel between the fourth microstrip transmission line and the fifth microstrip transmission line, and the source of the fifth field effect tube is connected in series with a resistor to ground.

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