CN101729036B - High stop-band restraining microwave intermediate frequency band pass filter - Google Patents

Abstract

The invention discloses a miniature microwave intermediate frequency bandpass filter with high stopband suppression, which comprises a surface-mounted 50-ohm impedance input port, an input inductance, a first-stage parallel resonance unit, a first-stage inter-stage coupling capacitor, and a first zero-point setting circuit, second interstage coupling capacitor, second stage parallel resonant unit, third interstage coupling capacitor, second zero point setting circuit, fourth interstage coupling capacitor, third stage parallel resonant unit, output inductor, surface mounted The 50-ohm impedance output port and ground terminal are realized by multi-layer low-temperature co-fired ceramic technology. The invention has the advantages of small size, light weight, high reliability, excellent electrical performance, linear change of phase frequency characteristics, good temperature stability, good batch consistency of electrical performance indicators, low mass production cost, etc., and is especially suitable for rockets, airborne , missiles, spacecraft, individual mobile communication terminals and other wireless communication handheld terminals, as well as corresponding systems that have strict requirements on volume, weight, performance, and reliability.

Description

Miniature Microwave IF Bandpass Filter with High Stopband Rejection

technical field

The invention belongs to electronic components used in microwave and millimeter wave communication, digital radar, individual satellite mobile communication terminal, military and civilian multi-mode and multi-channel communication system terminal, airborne, missile-borne, aerospace and other wireless communication systems, especially A miniature microwave intermediate frequency bandpass filter with high stopband suppression.

Background technique

In microwave and millimeter wave communication, radar and other systems, especially mobile handheld wireless communication terminals, individual satellite mobile communication terminals, military and civilian multi-mode and multi-channel communication system terminals, airborne, missile-borne, and aerospace communication systems, High stop band suppression Miniature microwave intermediate frequency band pass filter is the key electronic component in the receiving and transmitting branches of this band. The main technical indicators describing the performance of this component are: passband operating frequency range, stopband frequency range, passband input /Output VSWR, passband insertion loss, stopband attenuation, form factor, temperature stability, volume, weight, reliability, etc. Conventional design and manufacturing methods are at the low end of microwave frequency (300MHz~1GHz). Due to the long wavelength (wavelength 0.3m to 1m.), the volume of the filter is proportional to the working wavelength, so the volume is relatively large (generally about 45mm ×32mm×8mm), and the use of surface acoustic wave filter technology, although the volume can be reduced, but its electrical performance has the disadvantage of temperature drift, and the cost is high, the insertion loss is large, and the temperature stability and insertion loss requirements are high. Low applications are greatly restricted.

Contents of the invention

The purpose of the present invention is to provide a high-resistance-band-suppressed miniature microwave intermediate-frequency bandpass with small size, light weight, high reliability, good temperature performance, excellent electrical performance, high yield, good batch electrical performance consistency, and low cost. filter.

The technical solution to realize the object of the present invention is: a high stop band suppression miniature microwave intermediate frequency bandpass filter, including a surface-mounted 50 ohm impedance input port, an input inductance, a first-stage parallel resonant unit, and a first-stage inter-stage coupling capacitance , the first zero point setting circuit, the second interstage coupling capacitor, the second stage parallel resonant unit, the third interstage coupling capacitor, the second zero point setting circuit, the fourth interstage coupling capacitor, the third stage parallel resonant unit, Output inductor, surface-mounted 50-ohm impedance output port and ground terminal; the first-level parallel resonance unit is formed by parallel connection of the first inductor and the first capacitor, and the second-level parallel resonance unit is formed by the parallel connection of the second inductor and the second capacitor , the third parallel resonant unit is formed by the parallel connection of the third inductor and the third capacitor, the first zero point setting circuit is formed by the parallel connection of the first zero point inductance and the first zero point capacitor, and the second zero point setting circuit is formed by the second zero point setting circuit The zero-point inductance and the second zero-point capacitor are connected in parallel; one end of the surface-mounted 50-ohm impedance input port is connected to the input signal, the other end of the input port is connected to one end of the input inductance, and one end of the first-stage parallel resonance unit is connected to the other end of the input inductance. One end is connected to one end of the first interstage coupling capacitor, the other end of the first stage parallel resonance unit is connected to the ground, the other end of the first interstage coupling capacitor is connected to one end of the first zero point setting circuit, and the first The other end of the zero point setting circuit is connected to one end of the second interstage coupling capacitor, and the other end of the second interstage coupling capacitor is respectively connected to one end of the second stage parallel resonant unit and one end of the third interstage coupling capacitor, and the second stage is connected in parallel The other end of the resonance unit is grounded, the other end of the third interstage coupling capacitor is connected to the second zero point setting circuit, the other end of the second zero point setting circuit is connected to one end of the fourth interstage coupling capacitor, the first The other end of the coupling capacitor between the four stages is respectively connected to one end of the third-stage parallel resonance unit and one end of the output inductor, the other end of the third-stage parallel resonance unit is grounded, the other end of the output inductor is connected to one end of the output port, and the other end of the output port Output signal at one end; all input ports, input inductance, first stage parallel resonant unit, first interstage coupling capacitor, first zero point setting circuit, second interstage coupling capacitor, second stage parallel resonant unit, third stage The inter-coupling capacitor, the second zero-point setting circuit, the fourth-stage inter-coupling capacitor, the third-stage parallel resonant unit, the output inductor, the output port and the ground terminal are all realized by multi-layer low-temperature co-fired ceramic technology, in which the input inductor, output The inductance, the first zero-point inductance, and the second zero-point inductance are all realized by the strip line with distributed parameters; the coupling capacitors between the first, second, third and fourth stages are realized by dielectric plate capacitors and distributed parameter capacitors; the first stage parallel resonance The unit, the second-level parallel resonant unit, and the third-level parallel resonant unit are realized by using a distributed parameter five-layer folded coupled stripline structure, in which one end of each layer of stripline is suspended and the other end is grounded; the first zero point sets the inductance in the circuit , using distributed parameter stripline implementation, the first zero-point setting circuit between the first-level parallel resonant unit and the second-level parallel resonant unit, the first zero-point capacitance uses two parallel resonant units, the first level and the second level Between spatial coupling and distributed parameter capacitance implementation, the second In the second zero-point setting circuit between the first-stage parallel resonance unit and the third-stage parallel resonance unit, the inductance in the second zero-point setting circuit is realized by using a strip line with distributed parameters, and the second-stage parallel resonance unit is connected in parallel with the third-stage The second zero point capacitance in the second zero point setting circuit between the resonant units is realized by space coupling and distributed parameter capacitance between two parallel resonant units in the second stage and the third stage.

Compared with the prior art, the present invention has significant advantages: (1) small size, light weight and high reliability; (2) excellent electrical performance, such as low passband insertion loss and high stopband suppression; (3) electrical performance High temperature stability; (4) The circuit realizes a simple structure; (5) The electrical performance is consistent and can realize mass production; (6) The cost is low; (7) It is easy to use and install, and can be installed and installed by a fully automatic placement machine. Welding; (8) It is especially suitable for wireless communication handheld terminals such as rockets, airborne, missile-borne, spacecraft, and individual mobile communication terminals, as well as corresponding systems that have strict requirements on volume, weight, performance, and reliability.

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

Figure 1 is an electrical schematic diagram of the present invention.

Fig. 2 is a schematic diagram of the appearance and internal structure of the present invention.

Fig. 3 is a schematic structural diagram of the parallel resonance unit of the present invention.

Fig. 4 is a real photo of an embodiment of the present invention.

Fig. 5 is the main performance test results of the embodiment of the present invention.

Detailed ways

In conjunction with Fig. 1, Fig. 2, Fig. 3, a kind of high stop band suppression miniature microwave intermediate frequency bandpass filter of the present invention, comprises the 50 ohm impedance input port P1 of surface mount, input inductance L4, first stage parallel resonant unit L1, C1 , the first interstage coupling capacitor C4, the first zero point setting circuit L12, C12, the second interstage coupling capacitor C5, the second stage parallel resonant unit L2, C2, the third interstage coupling capacitor C6, the second zero point setting Circuit L23, C23, the coupling capacitor C7 between the fourth stage, the third stage parallel resonant unit L3, C3, the output inductor L5, the surface-mounted 50 ohm impedance output port P2 and the ground terminal; the input port P1 is connected to the input inductor L4, and the output The port P2 is connected to the output inductance L5, and the first-stage parallel resonant unit L1, C1, the second-stage parallel resonant unit L2, C2 and the third-stage parallel resonant unit L3, C3 between the output inductance L5 and the input inductance L4 are all grounded , the first inter-stage coupling capacitor C4 and the second inter-stage coupling capacitor C5 are connected in series between the first-stage parallel resonant unit L1, C1 and the second-stage parallel resonant unit L2, C2, and the first inter-stage coupling capacitor C4 and the second The first zero-point setting circuit L12, C12 is connected in series between the second-level inter-coupling capacitor C5; the third-level inter-level coupling capacitor C6, the second-level parallel resonant unit L2, C2 and the third-level parallel resonant unit L3, C3 are connected in series. There are four interstage coupling capacitors C7, and the second zero point setting circuits L23 and C23 are connected in series between the third interstage coupling capacitor C6 and the fourth interstage coupling capacitor C7.

In the high-resistance band suppression miniature microwave intermediate frequency band-pass filter of the present invention, one end of the 50-ohm impedance input port P1 installed on the surface is connected to the input signal, the other end of the input port P1 is connected to one end of the input inductance L4, and the first-stage parallel resonance unit L1, C1 It is formed by connecting the first inductance L1 and the first capacitor C1 in parallel. One end of the first-stage parallel resonance unit L1, C1 is respectively connected to the other end of the input inductance L4 and one end of the first inter-stage coupling capacitor C4. The first-stage parallel resonance The other end of the unit L1, C1 is connected to the ground terminal; the first zero point setting circuit L12, C12 is formed by the parallel connection of the first zero point inductance L12 and the first zero point capacitor C12, and the first interstage coupling capacitor C4 The other end is connected to one end of the first zero point setting circuit L12, C12, the other end of the first zero point setting circuit L12, C12 is connected to one end of the second interstage coupling capacitor C5, and the other end of the second interstage coupling capacitor C5 is respectively connected to One end of the second-level parallel resonant unit L2, C2 and one end of the third inter-level coupling capacitor C6, the second-level parallel resonant unit L2, C2 is formed by the parallel connection of the second inductance L2 and the second capacitor C2, and the second-level parallel resonance The other end of the unit L2, C2 is grounded, the other end of the third interstage coupling capacitor C6 is connected to the second zero point setting circuit L23, C23, and the second zero point setting circuit L23, C23 is connected by the second zero point inductance L23 and the second zero-point capacitor C23 in parallel, the other end of the second zero-point setting circuit L23, C23 is connected to one end of the fourth interstage coupling capacitor C7, and the other end of the fourth interstage coupling capacitor C7 is respectively connected to the third One end of the parallel resonance unit L3, C3 and one end of the output inductor L5, the third parallel resonance unit L3, C3 is formed by the parallel connection of the third inductor L3 and the third capacitor C3, the other end of the third parallel resonance unit L3, C3 Grounded, the other end of the output inductor L5 is connected to one end of the output port P2, and the other end of the output port P2 outputs a signal.

In the high stop band suppression miniature microwave intermediate frequency bandpass filter of the present invention, all input ports P1, input inductance L4, first-stage parallel resonant unit L1, C1, first inter-stage coupling capacitor C4, and first zero-point setting circuit L12 , C12, the second interstage coupling capacitor C5, the second stage parallel resonant unit L2, C2, the third interstage coupling capacitor C6, the second zero point setting circuit L23, C23, the fourth interstage coupling capacitor C7, the third stage Parallel resonant unit L3, C3, output inductor L5, output port P2 and ground terminal are realized by multi-layer low-temperature co-fired ceramic technology, in which input inductor L4, output inductor L5, first zero-point inductor L12, second zero-point inductor L23 is implemented by stripline with distributed parameters, and the three parallel resonant units C1, L1, C2, L2, C3, L3 are implemented by five-layer folded coupled stripline, as shown in Figure 3. Both the first zero-point capacitor C12 and the second zero-point capacitor C23 are used between the first and second-level parallel resonant units L1, C1, L2, C2, and the second and third-level parallel resonant units L2, C2, L3, and C3. Space coupling and distributed parameter capacitors are realized. The coupling capacitors C4, C5, C6 and C7 between the first, second, third and fourth stages are realized by dielectric plate capacitors and distributed parameter capacitors. The size (l×w×d) of the miniature microwave intermediate frequency bandpass filter with high stopband suppression is: 4.5mm×3.2mm×1.5mm, and the weight is less than 0.1 gram. Refer to Figure 2 for a schematic diagram of the appearance and internal structure.

The first-stage parallel resonant unit L1, C1, the second-stage parallel resonant unit L2, C2, and the third-stage parallel resonant unit L3, C3 of the high-stop band suppression miniature microwave intermediate frequency bandpass filter of the present invention adopt five-layer folding of distributed parameters The coupled stripline structure is realized (see Figure 2 and Figure 3), in which one end of each layer of stripline is suspended and the other end is grounded.

In the first zero-point setting circuits L12 and C12 between the first-stage parallel resonant unit and the second-stage parallel resonant unit of the high-stop band suppression miniature microwave intermediate frequency bandpass filter of the present invention, the inductance L12 in the first zero-point setting circuit, Stripline implementation using distributed parameters, the coupling capacitor C12 in the first zero point setting circuit between the first parallel resonant unit and the second parallel resonant unit adopts the spatial coupling and distributed parameters between the first and second two parallel resonant units Capacitor implementation, in the second zero-point setting circuit L23 and C23 between the second-level parallel resonant unit and the third-level parallel resonant unit, the inductance L23 in the second zero-point setting circuit is realized by using a strip line with distributed parameters, and the second The coupling capacitor C23 in the first zero-point setting circuit between the parallel resonance unit and the third parallel resonance unit is realized by spatial coupling and distributed parameter capacitance between the second and third parallel resonance units.

The working principle of the miniature microwave intermediate frequency bandpass filter with high stop band suppression of the present invention is as follows: the input broadband microwave signal passes through the input port P1 and reaches the end connected with L1 and C1 in the first-stage parallel resonant unit L1 and C1 through the input inductance L4 and one end of the first interstage coupling capacitor C4, at one end of the first stage parallel resonant unit L1, C1, among the broadband microwave signals, the microwave signal near the resonant frequency of the first parallel resonant unit passes through the first interstage The coupling capacitor C4 enters the first zero-point setting circuit L12 and C12 between the first-stage parallel resonant unit and the second-stage parallel resonant unit, and the microwave signals near the resonant frequency of other non-first parallel resonant units pass through the first-stage parallel resonant unit L1 , L1 and C1 in C1 are grounded to realize the first-stage filtering, and the first zero point sets the stopband microwave signal near the parallel resonance frequency of the circuit L12 and C12 (that is, the microwave signal near the first zero point frequency), because it presents high impedance Suppressed, the microwave frequency signal not near the first zero point reaches one end of the second interstage coupling capacitor C5 through the first zero point setting circuit L12, L12 and C12 in the C12, and reaches the second interstage coupling capacitor C5 through the second interstage coupling capacitor C5. One end of the connection between L2 and C2 in the parallel resonant unit L2 and C2 and one end of the third inter-stage coupling capacitor C6, after the microwave signal of the first-stage filter and the first zero-point setting circuit, the resonant frequency of the second parallel resonant unit Nearby microwave signals enter the second zero-point setting circuits L23 and C23 between the second-stage parallel resonant unit and the third-stage parallel resonant unit through the third inter-stage coupling capacitor C6, and the rest of the microwaves near the resonant frequency of the second parallel resonant unit The signal is grounded through L2 and C2 in the second-stage parallel resonant unit L2 and C2 to realize the second-stage filtering, and the second zero point sets the stopband microwave signal near the parallel resonant frequency of the circuit L23 and C23 (that is, the second zero point frequency nearby microwave signal), because it presents high impedance and is suppressed, the microwave frequency signal not near the second zero point reaches one end of the fourth interstage coupling capacitor C7 through the second zero point setting circuit L23, L23 and C23 in the C23, and passes through the second zero point setting circuit L23 and C23 The coupling capacitor C7 between the four stages reaches the third-stage parallel resonant unit L3, one end of the connection between L3 and C3 in C3 and one end of the output inductance L5, and passes through the first-stage filter, the second-stage filter, the first zero point setting circuit and the second stage. The microwave signal of the circuit is set at 20 points, the microwave signal near the resonant frequency of the third parallel resonant unit is connected to one end of the surface-mounted 50 ohm impedance output port P2 through the output inductance L5, and the microwave signals near the resonant frequency of the other non-third parallel resonant unit The signal is grounded through L3 and C3 in the third-level parallel resonance unit L3 and C3 to realize the third-level filtering, after the first-level filtering, the second-level filtering, the third-level filtering, the first zero point setting circuit and the second zero point The microwave signal of the point setting circuit is output through the other end of the 50 ohm impedance output port P2 installed on the surface, so as to realize the high stop band suppression microwave intermediate frequency band pass filter function.

The high-resistance band suppression miniature microwave intermediate frequency band-pass filter of the present invention is realized by the multi-layer low-temperature co-fired ceramic technology, and is formed by sintering low-temperature co-fired ceramic materials and metal patterns at a temperature of about 900 ° C, so it has very high reliability. Due to the three-dimensional integration and multi-layer folding structure and the metal shielding on the outer surface to achieve grounding and packaging, the volume is greatly reduced.

See Figure 4 for the physical photos and dimensions of the embodiment of the high stop band suppression miniature microwave intermediate frequency bandpass filter, and see Figure 5 for the main performance test results of the embodiment of the high stop band suppression miniature microwave intermediate frequency bandpass filter.

Claims (1)

1. one kind high stopband restraining microwave if bandpas filter, 50 ohmage input ports (P1), input inductance (L4), first order parallel resonance unit (L1, C1), first blocking condenser (C4), the first zero that it is characterized in that comprising mounted on surface are provided with between circuit (L12, C12), second blocking condenser (C5), parallel resonance unit, the second level (L2, C2), the third level 50 ohmage output port (P2) and earth terminals of coupling capacitance (C7), third level parallel resonance unit (L3, C3), outputting inductance (L5), mounted on surface between coupling capacitance (C6), the second reset circuit (L23, C23), the fourth stage; First order parallel resonance unit (L1, C1) is formed in parallel by first inductance (L1) and first electric capacity (C1); Parallel resonance unit, the second level (L2, C2) is formed in parallel by second inductance (L2) and second electric capacity (C2); Third level parallel resonance unit (L3, C3) is formed in parallel by the 3rd inductance (L3) and the 3rd electric capacity (C3); The first zero is provided with circuit (L12, C12) and is formed in parallel by first zero inductance (L12) and first zero electric capacity (C12), and the second reset circuit (L23, C23) is formed in parallel by second inductance at zero point (L23) and second minimum capacity (C23); 50 ohmage input ports (P1) termination input signal of mounted on surface; One end of another termination input inductance (L4) of input port (P1); One end of first order parallel resonance unit (L1, C1) is connected with the other end of input inductance (L4) and an end of first blocking condenser (C4) respectively; The other end of first order parallel resonance unit (L1, C1) links to each other with earth terminal; The other end of described first blocking condenser (C4) connects the end that the first zero is provided with circuit (L12, C12); The first zero is provided with an end of coupling capacitance (C5) between another termination second level of circuit (L12, C12); The other end of second blocking condenser (C5) connects an end of coupling capacitance (C6) between an end and the third level of parallel resonance unit, the second level (L2, C2) respectively; The other end ground connection of parallel resonance unit, the second level (L2, C2), the other end of coupling capacitance between the described third level (C6) is connected with the second reset circuit (L23, C23), and one end of coupling capacitance (C7) is connected between the other end of the second reset circuit (L23, C23) and the fourth stage; The other end of coupling capacitance between this fourth stage (C7) connects an end and outputting inductance (L5) end of third level parallel resonance unit (L3, C3) respectively; The other end ground connection of third level parallel resonance unit (L3, C3), the other end of outputting inductance (L5) is connected with an end of output port (P2), the other end output signal of output port (P2); All input ports (P1), input inductance (L4), first order parallel resonance unit (L1, C1), first blocking condenser (C4), the first zero are provided with between circuit (L12, C12), second blocking condenser (C5), parallel resonance unit, the second level (L2, C2), the third level between coupling capacitance (C6), the second reset circuit (L23, C23), the fourth stage coupling capacitance (C7), third level parallel resonance unit (L3, C3), outputting inductance (L5), output port (P2) and earth terminal and all adopt multilayer and realize that with LTCC technology wherein input inductance (L4), outputting inductance (L5), first zero inductance (L12), second inductance at zero point (L23) all adopt the strip line of distributed constant to realize; First, second, third and fourth blocking condenser (C4), (C5), (C6), (C7) adopt media plate electric capacity and distributed constant electric capacity to realize; First order parallel resonance unit (L1, C1), parallel resonance unit, the second level (L2, C2), third level parallel resonance unit (L3, C3) adopt five layers of folding coupling strip line structure of distributed constant to realize that wherein every layer of strip line one end is unsettled, other end ground connection; The first zero is provided with inductance in the circuit (L12); Adopt the strip line of distributed constant to realize; The first zero is provided with in the circuit first zero electric capacity (C12) and adopts space coupling and the realization of distributed constant electric capacity between the first order and two parallel resonance unit, the second level between first order parallel resonance unit and the parallel resonance unit, the second level; Between parallel resonance unit, the second level and the third level parallel resonance unit in the second reset circuit (L23, C23); Inductance (L23) in the second reset circuit; Adopt the strip line of distributed constant to realize, between parallel resonance unit, the second level and the third level parallel resonance unit in the second reset circuit second minimum capacity (C23) adopt space coupling and the realization of distributed constant electric capacity between the second level and two parallel resonance unit of the third level.

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