CN211125950U - Low pass filter, millimeter wave AAU system and communication device - Google Patents
Low pass filter, millimeter wave AAU system and communication device Download PDFInfo
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- CN211125950U CN211125950U CN201922209390.4U CN201922209390U CN211125950U CN 211125950 U CN211125950 U CN 211125950U CN 201922209390 U CN201922209390 U CN 201922209390U CN 211125950 U CN211125950 U CN 211125950U
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Abstract
The utility model relates to a low pass filter, millimeter wave AAU system and communication device. The low-pass filter comprises a high-low impedance microstrip line low-pass filtering structure and a coupler stub. The low-pass filtering structure of the high-low impedance microstrip line comprises a plurality of microstrip lines which are folded and are electrically connected in sequence. One end of the coupler branch is electrically connected with the signal detection module, and the other end of the coupler branch is grounded through a matched load. After the millimeter wave AIP antenna module is connected to an input port of the millimeter wave AIP antenna module, on one hand, standing wave detection, power detection, DPD function, harmonic wave and out-of-band spurious suppression of signals at the input port of the millimeter wave AIP antenna module can be realized; on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure are folded, the high-low impedance microstrip line low-pass filter structure is designed in a miniaturization mode, the size of the device is reduced to the maximum extent, the occupied space is small, and the miniaturization design can be realized while the planar circuit interconnection design is facilitated.
Description
Technical Field
The utility model relates to the field of communication technology, especially, relate to a low pass filter, millimeter wave AAU system and communication device.
Background
Conventionally, a millimeter wave AAU (Active Antenna Unit) system includes a transmitting terminal for transmitting an intermediate frequency signal, a local oscillator module, a mixer, a power amplifier, a low pass filter, and a millimeter wave AIP Antenna module. The transmitting terminal sends the intermediate frequency signal to the mixer, the mixer carries out mixing up-conversion on the intermediate frequency signal and the local oscillation signal transmitted by the local oscillation module, then the mixed up-conversion is transmitted to the power amplifier, the power amplifier amplifies the signal and transmits the amplified signal to the low-pass filter, and the low-pass filter carries out signal harmonic and spurious suppression processing on the signal transmitted by the power amplifier and then transmits the signal to the millimeter wave AIP antenna module. In conventional designs, the low-pass filter and the coupler are usually two independent devices, and the length of the link size is the sum of the two devices. In order to save space and reduce loss, a traditional high-power low-loss coupling filter usually adopts a mode of cascading a bidirectional coupler and a band-pass filter, and the filter design with the coupler is mainly realized through a cavity structure. However, a miniaturized design cannot be achieved.
SUMMERY OF THE UTILITY MODEL
Accordingly, there is a need to overcome the drawbacks of the prior art and to provide a low pass filter, a millimeter wave AAU system, and a communication apparatus, which can realize a compact design.
The technical scheme is as follows: a low pass filter comprising: the low-pass filter structure comprises a plurality of folded microstrip lines which are electrically connected in sequence, wherein a head end microstrip line at the head end part of the plurality of microstrip lines is used for being connected with the output end of the power amplifier, and a tail end microstrip line at the tail end part of the plurality of microstrip lines is used for being electrically connected with the millimeter wave AIP antenna module; and the coupler minor matters comprise a plurality of transmission lines which are electrically connected in sequence, the coupler minor matters and the high-low impedance microstrip line low-pass filter structures are arranged at intervals and are in mutual coupling fit, the coupler minor matters are matched with the head end microstrip line at the head end part and the tail end microstrip line at the tail end part to form a directional coupler, one end of the coupler minor matters is electrically connected with the signal detection module, and the other end of the coupler minor matters is arranged to be grounded through a matched load.
After the low-pass filter is connected to an input port of a millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function and harmonic and out-of-band spurious suppression of signals at the input port of the millimeter wave AIP Antenna module can be realized, and on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure are folded, the high-low impedance microstrip line low-pass filter structure is in a miniaturized design, the size of a device is reduced to the maximum extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit interconnection design is facilitated.
In one embodiment, the microstrip lines include a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a head microstrip line and a tail microstrip line; the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line and the fifth microstrip line are electrically connected in sequence; the first microstrip line and the second microstrip line are arranged in the same direction, and the fourth microstrip line and the fifth microstrip line are arranged in the same direction; the first microstrip line and the fourth microstrip line are arranged in parallel at intervals, and the second microstrip line and the fifth microstrip line are arranged in parallel at intervals; the first microstrip line is electrically connected with the signal detection module through the head end microstrip line, and the fifth microstrip line is electrically connected with the millimeter wave AIP antenna module through the tail end microstrip line.
In one embodiment, the setting direction of the first microstrip line is perpendicular to the setting direction of the head microstrip line and the setting direction of the tail microstrip line, the setting direction of the first microstrip line is perpendicular to the setting direction of the third microstrip line, and the setting direction of the first microstrip line is parallel to the setting direction of the fourth microstrip line.
In one embodiment, the length L6 of the head microstrip line is the same as the length L7 of the tail microstrip line, and the width W6 of the head microstrip line is the same as the width W7 of the tail microstrip line.
In one embodiment, a straight line passing through a center point of the third microstrip line and perpendicular to the third microstrip line is defined as a symmetry axis P, and the high-low impedance microstrip line low-pass filter structure is arranged axisymmetrically with respect to the symmetry axis P.
In one embodiment, the length L of the first microstrip line is 3.4mm to 4.2mm, the width W1 is 2mm to 2.8mm, the length L of the second microstrip line is 2.5mm to 3.3mm, the width W2 is 0.1mm to 0.3mm, the length L.4 mm to 7.2mm, the width W3 is 2mm to 2.8mm, the length L of the fourth microstrip line is 2.5mm to 3.3mm, the width W4 is 0.1mm to 0.3mm, the length L of the fifth microstrip line is 3.4mm to 4.2mm, the width W5 is 2mm to 2.8mm, the length L of the head microstrip line is 1.5mm to 2.5mm, the width W6 of the head microstrip line is 0.9mm to 1.3mm, the length of the tail end of the microstrip line is 1.5mm to 2.6859 mm, and the width W7.6853 mm.
In one embodiment, one end of the head-end microstrip line connected to the first microstrip line is a tapered section, the width of which gradually decreases toward a direction close to the first microstrip line; and one end of the tail end microstrip line, which is connected with the fifth microstrip line, is a tapered section with the width gradually reduced towards the direction close to the fifth microstrip line.
In one embodiment, the coupler stub includes a first transmission line and two second transmission lines; the first transmission line and the high-low impedance microstrip line low-pass filtering structure are arranged at intervals, and a plurality of tooth parts at intervals are arranged on one side of the first transmission line facing the high-low impedance microstrip line low-pass filtering structure; the two second transmission lines are respectively connected with two ends of the first transmission line.
In one embodiment, the second transmission line comprises a first-component segment and a second-component segment; one end of the first segment is connected with the first transmission line, the other end of the first segment is connected with the second segment, the width of the first segment is smaller than that of the second segment, and the end of the second segment connected with the first segment is a gradual change segment, the width of which is gradually reduced towards the direction close to the first segment.
In one embodiment, the shape of the tooth is triangular, square or semicircular; the interval S between the adjacent tooth parts is 0.12 mm-0.18 mm, the height h of the tooth parts is 0.4 mm-0.8 mm, and the width a of the tooth parts is 0.4 mm-1.2 mm.
A millimeter wave AAU system comprises the low pass filter, a transmitting end for transmitting intermediate frequency signals, a local oscillator module, a mixer, a power amplifier, a signal detection module and a millimeter wave AIP antenna module; the transmitting end and the local oscillator module are both connected with the input end of the mixer, the output end of the mixer is connected with the input end of the power amplifier, the output end of the power amplifier is connected with the head-end microstrip line, and the input port of the millimeter wave AIP antenna module is connected with the tail-end microstrip line; one end of the coupler branch is electrically connected with the signal detection module, and the other end of the coupler branch is grounded through a matched load.
After the millimeter wave AAU system is connected to an input port of a millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function and harmonic wave and out-of-band spurious suppression of an input port signal of the millimeter wave AIP Antenna module can be realized, and on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure are folded, the high-low impedance microstrip line low-pass filter structure is in a miniaturized design, the size of a device is reduced to the maximum extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit interconnection design is facilitated.
A communication device comprises the low-pass filter.
After the communication device is connected to an input port of a millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function and harmonic wave and out-of-band spurious suppression of signals at the input port of the millimeter wave AIP Antenna module can be realized, and on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure are folded, the high-low impedance microstrip line low-pass filter structure is in a miniaturized design, the size of the device is reduced to the maximum extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit interconnection design is facilitated.
Drawings
Fig. 1 is a schematic structural diagram of a low-pass filter according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a low-pass filter according to another embodiment of the present invention;
fig. 3 is a schematic structural diagram of a millimeter wave AAU system according to an embodiment of the present invention;
fig. 4 is a graph showing the insertion loss, return loss, and out-of-band rejection electromagnetic simulation curves of the low pass filter according to an embodiment of the present invention;
fig. 5 is a simulation curve of the coupling degree and the isolation degree of the coupler branch in the low pass filter according to an embodiment of the present invention.
Reference numerals:
100. a low-pass filter; 110. a high-low impedance microstrip line low-pass filter structure; 111. a first microstrip line; 112. A second microstrip line; 113. a third microstrip line; 114. a fourth microstrip line; 115. a fifth microstrip line; 116. a head end microstrip line; 1161. a first beveled edge; 117. a tail end microstrip line; 1171. a second beveled edge; 120. a coupler stub; 121. a first transmission line; 1211. a tooth portion; 122. a second transmission line; 1221. a first component section; 1222. a second section; 1223. a third beveled edge; 200. a transmitting end; 300. a local oscillation module; 400. A mixer; 500. a power amplifier; 600. a signal detection module; 610. a digital-to-analog conversion module; 620. a digital signal processing module; 700. a millimeter wave AIP antenna module; 800. and a circuit control module.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description of the present invention, it is to be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.
In one embodiment, referring to fig. 1 to 3, a low-pass filter 100 includes a high-low impedance microstrip line low-pass filter structure 110 and a coupler stub 120. The high-low impedance microstrip line low-pass filter structure 110 includes a plurality of microstrip lines which are folded and electrically connected in sequence. The head microstrip line 116 at the head of the plurality of microstrip lines is used to connect to the output end of the power amplifier 500, and the tail microstrip line 117 at the tail of the plurality of microstrip lines is used to electrically connect to the millimeter wave AIP antenna module 700. The coupler stub 120 comprises a plurality of transmission lines which are electrically connected in sequence, the coupler stub 120 and the high-low impedance microstrip line low-pass filter structure 110 are arranged at intervals and are in mutual coupling fit, the coupler stub 120 is matched with a head-end microstrip line 116 at a head end part and a tail-end microstrip line 117 at a tail end part to form a directional coupler, one end of the coupler stub 120 is electrically connected with the signal detection module 600, and the other end of the coupler stub 120 is grounded through a matched load.
After the low-pass filter 100 is connected to the input port of the millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function, and harmonic and out-of-band spurious suppression of signals at the input port of the millimeter wave AIP Antenna module 700 can be realized, and on the other hand, since the plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure 110 are folded, the high-low impedance microstrip line low-pass filter structure 110 is designed in a miniaturized manner, so that the size of the device is reduced to the greatest extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit is designed in an interconnected manner.
Further, the microstrip lines include a first microstrip line 111, a second microstrip line 112, a third microstrip line 113, a fourth microstrip line 114, a fifth microstrip line 115, a head microstrip line 116, and a tail microstrip line 117. The first microstrip line 111, the second microstrip line 112, the third microstrip line 113, the fourth microstrip line 114 and the fifth microstrip line 115 are electrically connected in sequence. The first microstrip line 111 and the second microstrip line 112 are arranged in the same direction, and the fourth microstrip line 114 and the fifth microstrip line 115 are arranged in the same direction. The first microstrip line 111 and the fourth microstrip line 114 are arranged in parallel at an interval, and the second microstrip line 112 and the fifth microstrip line 115 are arranged in parallel at an interval. The first microstrip line 111 is electrically connected to the signal detection module 600 through the head microstrip line 116, and the fifth microstrip line 115 is electrically connected to the millimeter wave AIP antenna module 700 through the tail microstrip line 117. The first microstrip line 111, the second microstrip line 112, the third microstrip line 113, the fourth microstrip line 114 and the fifth microstrip line 115 are equivalent to a five-order low-pass filter, and can pass signals below a preset cutoff frequency and inhibit and filter signals above the cutoff frequency. For the fifth-order low-pass filter, the head microstrip line 116 and the tail microstrip line 117 both function as an electrical connection, and the head microstrip line 116 is electrically connected to the output end of the power amplifier 500 to introduce the transmission signal into the fifth-order low-pass filter; the end microstrip line 117 is electrically connected to the input port of the millimeter wave AIP antenna module 700, and transmits a clean, stable, high-quality transmission signal to the millimeter wave AIP antenna module 700. Of course, the high-low impedance microstrip line low-pass filtering structure 110 is not limited to be designed as a fifth-order low-pass filter, and can also be designed as a low-pass filter of other orders.
Referring to fig. 1 or fig. 2 again, the folding manner of the high-low impedance microstrip line low-pass filter structure 110 may specifically be: the setting direction of the first microstrip line 111 is perpendicular to the setting direction of the head microstrip line 116 and the setting direction of the tail microstrip line 117, the setting direction of the first microstrip line 111 is perpendicular to the setting direction of the third microstrip line 113, and the setting direction of the first microstrip line 111 is parallel to the setting direction of the fourth microstrip line 114. So, can guarantee the performance of high low impedance microstrip line low pass filter structure 110 this application on the one hand, on the other hand can realize the miniaturized design of device, reduces volume size and occupation space.
As an alternative, the arrangement direction of the first microstrip line 111 forms an angle with the arrangement direction of the head microstrip line 116 and the arrangement direction of the tail microstrip line 117, respectively, which is, for example, in a range of 60 degrees to 120 degrees.
As an alternative, an angle between the arrangement direction of the first microstrip line 111 and the arrangement direction of the third microstrip line 113 is, for example, in a range of 0 degree to 30 degrees.
In one embodiment, the length L6 of the head microstrip line 116 is the same as the length L7 of the tail microstrip line 117, and the width W6 of the head microstrip line 116 is the same as the width W7 of the tail microstrip line 117.
In one embodiment, a straight line passing through a center point of the third microstrip line 113 and perpendicular to the third microstrip line 113 is defined as a symmetry axis P about which the high-low impedance microstrip line low-pass filter structure 110 is disposed axisymmetrically.
In one embodiment, the length L of the first microstrip line 111 is 3.4mm to 4.2mm, the width W1 is 2mm to 2.8mm, the length L of the second microstrip line 112 is 2.5mm to 3.3mm, the width W2 is 0.1mm to 0.3mm, the length L.4 mm to 7.2mm of the third microstrip line 113 is 2mm to 2.8mm, the length L of the fourth microstrip line 114 is 2.5mm to 3.3mm, the width W4 is 0.1mm to 0.3mm, the length L of the fifth microstrip line 115 is 3.4mm to 4.2mm, the width W5 is 2mm to 2.8mm, the length L of the first microstrip line 116 is 1.5mm to 2.5mm, the width W6 of the tail end is 0.9mm to 1.3mm, the length of the microstrip line 117 is 1.7 mm to 2. 7 mm, and the width W6851.9 mm to 1.3 mm.
Specifically, the head microstrip line 116 and the tail microstrip line 117 are both 50 Ω impedance microstrip lines, for example.
Specifically, the length L1 of the first microstrip line 111 is 3.8mm, the width W1 is 2.4mm, the length L2 of the second microstrip line 112 is 2.9mm, the width W2 is 0.2mm, the length L3 of the third microstrip line 113 is 6.8mm, the width W3 is 2.4mm, the length L4 of the fourth microstrip line 114 is 2.9mm, the width W4 is 0.2mm, the length L5 of the fifth microstrip line 115 is 3.8mm, the width W5 is 2.4mm, the length L6 of the first microstrip line 116 is 2mm, the width W6 is 1.1mm, the length L7 of the end microstrip line 117 is 2mm, and the width W7 is 1.1 mm.
In an embodiment, referring to fig. 1 and fig. 2, an end of the head microstrip line 116 connected to the first microstrip line 111 is a tapered section whose width gradually decreases toward a direction close to the first microstrip line 111. Specifically, a first oblique edge 1161 is disposed on a side portion of one end of the head microstrip line 116 connected to the first microstrip line 111. In this way, a better feed transmission of the signal on the head microstrip line 116 to the first microstrip line 111 can be achieved.
In addition, similarly, one end of the terminal microstrip line 117 connected to the fifth microstrip line 115 is a tapered section whose width gradually decreases toward a direction close to the fifth microstrip line 115. Specifically, a second oblique side 1171 is provided on a side portion of one end of the end microstrip line 117 connected to the fifth microstrip line 115. In this way, a better feed transmission of the signal on the fifth microstrip line 115 to the end microstrip line 117 can be achieved.
In one embodiment, the coupler stub 120 includes a first transmission line 121 and two second transmission lines 122. The first transmission line 121 and the high-low impedance microstrip line low-pass filter structure 110 are arranged at intervals, and a plurality of teeth 1211 at intervals are arranged on one side of the first transmission line 121 facing the high-low impedance microstrip line low-pass filter structure 110. The two second transmission lines 122 are respectively connected to two ends of the first transmission line 121. Thus, under the action of the plurality of teeth 1211 of the first transmission line 121, the difference of the odd-coupled mode phase velocities of the microstrip coupling transmission line can be effectively reduced, and the directivity of the directional coupler can be greatly improved.
Specifically, the first transmission line 121 and the third microstrip line 113 are arranged in parallel and spaced apart. As described above, when the low-pass filter 100 needs to have both the power detection function and the standing wave detection function, it is advantageous to realize that the shape and size of the head microstrip line 116 is the same as the shape and size of the tail microstrip line 117. Of course, as an alternative, the first transmission line 121 may be arranged in parallel with the end microstrip line 117 at an interval, and in order to implement the low-pass filter 100 with both the power detection function and the standing wave detection function, the length of the end microstrip line 117 is usually greater than that of the head microstrip line 116, so that the overall size is larger than that of the first transmission line 121 arranged in parallel with the third microstrip line 113 at an interval.
In one embodiment, the second transmission line 122 includes a first segment 1221 and a second segment 1222. One end of the first segment 1221 is connected to the first transmission line 121, the other end of the first segment 1221 is connected to the second segment 1222, the width of the first segment 1221 is smaller than the width of the second segment 1222, and the end of the second segment 1222 connected to the first segment 1221 is a gradually-changing segment whose width gradually decreases toward the direction close to the first segment 1221. Specifically, the side of the end of the second body segment 1222 connected to the first body segment 1221 is provided with a third chamfered edge 1223. Thus, on the one hand, the first segment 1221 can be matched to the impedance of the second segment 1222, and on the other hand, the transmission signal of the first segment 1221 can be transmitted to the second segment 1222 more smoothly.
In one embodiment, the shape of the teeth 1211 is triangular, square or semi-circular.
In one embodiment, the interval S between adjacent teeth 1211 is 0.12mm to 0.18mm, the height h of the teeth 1211 is 0.4mm to 0.8mm, and the width a of the teeth 1211 is 0.4mm to 1.2 mm.
Specifically, the interval S between adjacent teeth 1211 is 0.15mm, the height h of the teeth 1211 is 0.6mm, and the width a of the teeth 1211 is 0.8 mm.
In an embodiment, referring to fig. 1 to fig. 3, a millimeter wave AAU system includes the low pass filter 100 described in any of the above embodiments, and further includes a transmitting end 200 for transmitting an intermediate frequency signal, a local oscillation module 300, a mixer 400, a power amplifier 500, a signal detection module 600, and a millimeter wave AIP antenna module 700. The transmitting terminal 200 and the local oscillator module 300 are both connected to the input terminal of the mixer 400, the output terminal of the mixer 400 is connected to the input terminal of the power amplifier 500, the output terminal of the power amplifier 500 is connected to the head-end microstrip line 116, and the input port of the millimeter wave AIP antenna module 700 is connected to the tail-end microstrip line 117. One end of the coupler branch 120 is electrically connected to the signal detection module 600, and the other end of the coupler branch 120 is grounded through a matching load.
After the millimeter wave AAU system is connected to the input port of the millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function, and harmonic and out-of-band spurious suppression of the input port signal of the millimeter wave AIP Antenna module 700 can be realized, and on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure 110 are folded, the high-low impedance microstrip line low-pass filter structure 110 is designed in a miniaturized manner, so that the size of the device is reduced to the maximum extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit is designed in an interconnected manner. In addition, the low-pass filter 100 of the above embodiment performs signal harmonic and spurious suppression, power detection, standing wave detection, and DPD functions, and can provide a clean, stable, and high-quality input signal for the rear-end millimeter wave AIP module.
Further, the signal detection module 600 includes a digital-to-analog conversion module 610 and a digital signal processing module 620. One end of the coupler branch 120 is connected to a digital-to-analog conversion processing module, and the digital-to-analog conversion processing module is connected to the digital signal processing module 620.
Further, the millimeter wave AAU system further includes a circuit control module 800. The coupler branch 120 is connected to the digital-to-analog conversion processing module through the circuit control module 800.
When the power detection state needs to be adjusted, the circuit control module 800 switches to the first working state, and is configured to control the second transmission line 122 close to the head-end microstrip line 116 to be connected to the digital-to-analog conversion processing module, and the other second transmission line 122 is connected to a 50 Ω resistor and then grounded, at this time, the second transmission line 122 close to the head-end microstrip line 116 is coupled to the head-end microstrip line 116, the head-end microstrip line 116 not only transmits the transmission signal to the millimeter wave AIP antenna module 700 after filtering through the fifth-order low pass filter, but also transmits the transmission signal to the second transmission line 122 close to the head-end microstrip line 116 in a coupled manner, and then the second transmission line 122 close to the head-end microstrip line 116 transmits the transmission signal to the signal detection module 600, and the signal detection module 600 accordingly can achieve the power. At this time, since the other second transmission line 122 is grounded after being connected with a matching resistor of, for example, 50 Ω, the impedance of the second transmission line 122 can be matched, and the interference effect of the idle second transmission line 122 on the other three ports can be avoided.
When the standing wave detection state needs to be adjusted, the circuit control module 800 switches to a second working state, and is configured to control the second transmission line 122 close to the tail microstrip line 117 to be connected to the digital-to-analog conversion processing module, and the other second transmission line 122 is connected to a 50 Ω resistor and then grounded, at this time, the second transmission line 122 close to the tail microstrip line 117 is coupled to the head microstrip line 116, the tail microstrip line 117 can transmit the standing wave signal of the millimeter wave AIP antenna module 700 to the second transmission line 122 close to the tail microstrip line 117, and the second transmission line 122 close to the tail microstrip line 117 then transmits the standing wave signal to the signal detection module 600, and the signal detection module 600 can correspondingly implement the standing wave detection function. Similarly, since the other second transmission line 122 is grounded after being connected to a resistor of, for example, 50 Ω, the impedance of the second transmission line 122 can be matched, and the interference effect of the idle second transmission line 122 on the other three ports can be avoided.
In one embodiment, a communication device comprises the low pass filter 100 of any of the above embodiments.
After the communication device is connected to the input port of the millimeter wave AIP (Antenna in package) Antenna module, on one hand, standing wave detection, power detection, DPD (Digital Pre-Distortion) function, and harmonic and out-of-band spurious suppression of the input port signal of the millimeter wave AIP Antenna module 700 can be realized, and on the other hand, because a plurality of microstrip lines of the high-low impedance microstrip line low-pass filter structure 110 are folded, the high-low impedance microstrip line low-pass filter structure 110 is designed in a miniaturized manner, so that the size of the device is reduced to the maximum extent, the occupied space is small, and the miniaturized design can be realized while the planar circuit is designed in an interconnected manner.
Referring to fig. 4 and 5, fig. 4 is a simulation graph of insertion loss, return loss and out-of-band rejection of the low-pass filter 100 according to the present embodiment. As can be seen from fig. 4, when the frequency point of the signal is 3.6GHz, the insertion loss is about 0.25dB, and the second harmonic suppression is greater than 19dB, which satisfies the design expectation. Fig. 5 is a simulation curve of the coupling degree and the isolation degree of the coupler branch 120 in the low-pass filter 100 according to the present embodiment. As can be seen from fig. 5, the insertion loss is about 1.4dB in the 800MHz bandwidth (2.8GHz-3.6GHz), and the directivity is greater than 23dB (directivity is isolation-coupling), which satisfies the design expectation.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (12)
1. A low pass filter, comprising:
the low-pass filter structure comprises a plurality of folded microstrip lines which are electrically connected in sequence, wherein a head end microstrip line at the head end part of the plurality of microstrip lines is used for being connected with the output end of the power amplifier, and a tail end microstrip line at the tail end part of the plurality of microstrip lines is used for being electrically connected with the millimeter wave AIP antenna module; and
the coupler minor matters, the coupler minor matters is including a plurality of transmission lines that connect electrically in proper order, the coupler minor matters with interval setting and mutual coupling cooperation between the high-low impedance microstrip line low pass filter structure, the coupler minor matters forms directional coupler with the cooperation of the head end microstrip line at head end position, the terminal microstrip line at terminal position, wherein one end of coupler minor matters is used for with signal detection module electric connection, the other end of coupler minor matters is used for setting up through matching load ground connection.
2. The low-pass filter according to claim 1, wherein the microstrip lines include a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, a fifth microstrip line, a head-end microstrip line, and a tail-end microstrip line; the first microstrip line, the second microstrip line, the third microstrip line, the fourth microstrip line and the fifth microstrip line are electrically connected in sequence; the first microstrip line and the second microstrip line are arranged in the same direction, and the fourth microstrip line and the fifth microstrip line are arranged in the same direction; the first microstrip line and the fourth microstrip line are arranged in parallel at intervals, and the second microstrip line and the fifth microstrip line are arranged in parallel at intervals; the first microstrip line is electrically connected with the signal detection module through the head end microstrip line, and the fifth microstrip line is electrically connected with the millimeter wave AIP antenna module through the tail end microstrip line.
3. The low-pass filter according to claim 2, wherein the direction of arrangement of the first microstrip line is perpendicular to the direction of arrangement of the head microstrip line and the direction of arrangement of the tail microstrip line, respectively, the direction of arrangement of the first microstrip line is perpendicular to the direction of arrangement of the third microstrip line, and the direction of arrangement of the first microstrip line is parallel to the direction of arrangement of the fourth microstrip line.
4. The low pass filter of claim 2, wherein the length L6 of the head microstrip line is equal to the length L7 of the tail microstrip line, and the width W6 of the head microstrip line is equal to the width W7 of the tail microstrip line.
5. The low-pass filter according to claim 2, wherein a straight line passing through a center point of the third microstrip line and perpendicular to the third microstrip line is defined as a symmetry axis P about which the high-low impedance microstrip line low-pass filter structure is disposed axisymmetrically.
6. The low pass filter of claim 2, wherein the first microstrip line has a length L mm to 4.2mm and a width W1 mm to 2.8mm, the second microstrip line has a length L mm to 3.3mm and a width W2 of 0.1mm to 0.3mm, the third microstrip line has a length L.4 mm to 7.2mm and a width W3 of 2mm to 2.8mm, the fourth microstrip line has a length L mm to 3.3mm and a width W4 of 0.1mm to 0.3mm, the fifth microstrip line has a length L mm to 3.4mm to 4.2mm and a width W5 of 2mm to 2.8mm, the first microstrip line has a length 466 mm to 2.5mm and a width W6 mm to 1.3mm, and the second microstrip line has a length 62 mm to 2.8mm and a width W6851.9 mm to 2.3 mm.
7. The low-pass filter according to claim 2, wherein the end of the head-end microstrip line connected to the first microstrip line is a tapered section whose width gradually decreases toward a direction close to the first microstrip line; and one end of the tail end microstrip line, which is connected with the fifth microstrip line, is a tapered section with the width gradually reduced towards the direction close to the fifth microstrip line.
8. A low-pass filter as claimed in claim 1, characterized in that the coupler stub comprises a first transmission line and two second transmission lines; the first transmission line and the high-low impedance microstrip line low-pass filtering structure are arranged at intervals, and a plurality of tooth parts at intervals are arranged on one side of the first transmission line facing the high-low impedance microstrip line low-pass filtering structure; the two second transmission lines are respectively connected with two ends of the first transmission line.
9. A low-pass filter as claimed in claim 8, characterized in that the second transmission line comprises a first and a second component section; one end of the first segment is connected with the first transmission line, the other end of the first segment is connected with the second segment, the width of the first segment is smaller than that of the second segment, and the end of the second segment connected with the first segment is a gradual change segment, the width of which is gradually reduced towards the direction close to the first segment.
10. The low pass filter according to claim 8, wherein the teeth are triangular, square or semi-circular in shape; the interval S between the adjacent tooth parts is 0.12 mm-0.18 mm, the height h of the tooth parts is 0.4 mm-0.8 mm, and the width a of the tooth parts is 0.4 mm-1.2 mm.
11. A millimeter wave AAU system, comprising the low pass filter according to any one of claims 1 to 10, further comprising a transmitting terminal for transmitting an intermediate frequency signal, a local oscillator module, a mixer, a power amplifier, a signal detection module, and a millimeter wave AIP antenna module; the transmitting end and the local oscillator module are both connected with the input end of the mixer, the output end of the mixer is connected with the input end of the power amplifier, the output end of the power amplifier is connected with the head-end microstrip line, and the input port of the millimeter wave AIP antenna module is connected with the tail-end microstrip line; one end of the coupler branch is electrically connected with the signal detection module, and the other end of the coupler branch is grounded through a matched load.
12. A communication device comprising a low-pass filter according to any one of claims 1 to 10.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110994095A (en) * | 2019-12-11 | 2020-04-10 | 京信通信技术(广州)有限公司 | Low pass filter, millimeter wave AAU system and communication device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110994095A (en) * | 2019-12-11 | 2020-04-10 | 京信通信技术(广州)有限公司 | Low pass filter, millimeter wave AAU system and communication device |
| CN110994095B (en) * | 2019-12-11 | 2024-04-26 | 京信网络系统股份有限公司 | Low-pass filter, millimeter wave AAU system and communication device |
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Effective date of registration: 20210805 Address after: 510663 Shenzhou Road 10, Guangzhou Science City, Guangzhou economic and Technological Development Zone, Guangzhou, Guangdong Patentee after: Jingxin Network System Co.,Ltd. Address before: 510730, No. 6, Jin Lu, Guangzhou economic and Technological Development Zone, Guangdong, Guangzhou Patentee before: COMBA TELECOM TECHNOLOGY (GUANGZHOU) Ltd. |
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