阅读说明：本技术 一种lc开关滤波器组分段滤波电路 (LC switch filter bank segmented filter circuit ) 是由 刘文根 唐维 胡波 陈慧 付航 于 2021-08-26 设计创作，主要内容包括：发明公开了一种LC开关滤波器组分段滤波电路,主要解决现有滤波器的滤波频段都是固定的,无法根据不同的抑制需求获得相应的滤波频率的问题。该滤波电路包括4个射频开关芯片U1、U2、U3、U4及频率段分别为20-80MHz,80-140MHz,140-250MHz,250-420MHz,420-710MHz,710-1220MHz,1.2-2GHz的滤波电路。通过上述设计,发明通过设置多频段的滤波电路,可通过射频开关选择对应的滤波频段。此技术于低频段方便调试,可根据不同抑制需求调出相应指标,成本低,且可通过开关选择实现较宽频率谐波拆分成多段窄带频率,通过LC滤波器实现谐波频率抑制,可灵活变通,根据自己实际需求实现分段选择,可应用多种场景,减低滤波器调试配置成本。因此,适宜推广应用。(The invention discloses a segmented filter circuit of an LC switch filter bank, which mainly solves the problem that the filter frequency band of the existing filter is fixed and the corresponding filter frequency can not be obtained according to different suppression requirements. The filter circuit comprises 4 radio frequency switch chips U1, U2, U3 and U4 and filter circuits with frequency sections of 20-80MHz, 80-140MHz, 140-250MHz, 250-420MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz respectively. Through the design, the invention can select the corresponding filtering frequency band through the radio frequency switch by setting the filtering circuit with multiple frequency bands. The technology is convenient to debug in a low frequency band, can call corresponding indexes according to different suppression requirements, is low in cost, can realize the splitting of wider frequency harmonic waves into multiple sections of narrow-band frequencies through switch selection, realizes the suppression of harmonic frequencies through an LC filter, can be flexibly changed, realizes the segmentation selection according to the actual requirements, can be applied to various scenes, and reduces the debugging and configuration cost of the filter. Therefore, the method is suitable for popularization and application.)

1. An LC switch filter bank segmented filter circuit is characterized by comprising 4 radio frequency switch chips U1, U2, U3 and U4 and filter circuits with frequency segments of 20-80MHz, 80-140MHz, 140-250MHz, 250-420MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz respectively;

the filter circuit with the frequency segments of 80-140MHz, 140-250MHz and 250-420MHz is connected between the two radio frequency switch chips U1 and U2, the circuit topological structures are the same, and the circuit element parameters are different;

the filter circuit with the frequency segments of 20-80MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz is connected between the other two radio frequency switch chips U3 and U4; the radio frequency switch chips U1 and U3 are connected.

2. The segmented filter circuit of the LC switch filter bank as claimed in claim 1, wherein the RF switch chips U1, U2 are model HMC24LP 3; the filter circuit with the frequency band of 80-140MHz comprises a resistor R336 connected with an RF1 pin of a radio frequency switch chip U1, a resistor R337 connected with an RF4 pin of a switch chip U2, and a plurality of capacitors and LC filter circuits which are alternately arranged and connected between the resistor R336 and the resistor R337.

3. The LC switched filter bank segmented filter circuit as claimed in claim 1, wherein the RF switch chip U3 has a model number XND42482MQI, and the RF switch chip U4 has a model number HMC252AQS 24E; the RF8 pin of the radio frequency switch chip U3 is connected with the RFC pin of the radio frequency switch chip U1 through a capacitor C190.

4. The LC switch filter bank segmented filter circuit as claimed in claim 3, wherein the filter circuit with the frequency range of 20-80MHz comprises a resistor R672 connected with an RF4 pin of a radio frequency switch chip U3, inductors L200, L201, L204 connected with one end of the resistor C672 at the other end after series connection, capacitors C668, C669, C670 connected with two ends of the inductors L200, L201, L204 in parallel respectively, capacitors C676, C678, C675 connected with input ends of the inductors L200, L201, L204 at one end and grounded at the other end, an inductor L211 connected with an output end of the inductor L204 at one end and grounded at the other end, a capacitor C674 connected with two ends of the inductor L211 in parallel, a capacitor C673 connected with an output end of the inductor L204 at one end, an inductor L218 connected with one end and grounded at the other end of the capacitor C673 and a capacitor C671 connected with a common end of the inductor L218; the other end of the capacitor C671 is connected to the RF2 pin of the RF switch chip U4 through a resistor R345.

5. The LC switch filter bank segmented filter circuit as claimed in claim 3, wherein the filter circuit with the frequency band of 420-710MHz comprises a resistor R372 connected to the RF6 pin of the RF switch chip U3, a capacitor C427 connected to the other end of the resistor R372, an inductor L129 and a capacitor C453 connected to the other end of the capacitor C427, inductors L128 and L130 connected to the other end of the capacitor C453, a capacitor C520 connected in parallel to the two ends of the inductor L128, an inductor L134 and a capacitor C490 connected to the other end of the inductor L128, an inductor L139 and a low pass filter F166 connected to the other end of the capacitor C490, and a capacitor C459 connected to the other end of the low pass filter F166, the other end of the capacitor C459 being connected to the RF4 pin of the RF switch chip U4 via the resistor R373; the other ends of the inductors L129, L130, L134, and L139 are grounded.

6. The LC switch filter bank segmented filter circuit as claimed in claim 3, wherein the filter circuit with the frequency band of 710-1220MHz comprises a resistor R374 connected to the RF5 pin of the RF switch chip U3, a capacitor C524 connected to the other end of the resistor R374, a low-pass filter F154 connected to the other end of the capacitor C524, an inductor L142 and a capacitor C526 of a capacitor C459 connected to the other end of the low-pass filter F154, inductors L191 and L141 connected to the other end of the capacitor C526, a capacitor C644 connected in parallel to both ends of the inductor L141, an inductor L197 and a capacitor C628 connected to the other end of the inductor L141, a low-pass filter F155, and a capacitor C527 connected to the other end of the low-pass filter F155, the other end of the capacitor C527 being connected to the RF3 pin of the RF switch chip U4 via the resistor R375; the other ends of the inductors L142, L191, L197 and L198 are grounded.

7. The LC switch filter bank segmented filter circuit as claimed in claim 3, wherein the filter circuit with the frequency band of 1.2-2GHz comprises a resistor R370 connected to the RF7 pin of the RF switch chip U3, a capacitor C362 connected to the other end of the resistor R370, a capacitor C363 and an inductor L125 connected to the other end of the capacitor C362, a capacitor C384 connected to the other end of the inductor L125 at one end and grounded at the other end, a capacitor C364 and an inductor L126 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L126 at one end and grounded at the other end, a capacitor C367 and an inductor L127 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L127 at one end and grounded at the other end, a capacitor C368 connected to the other end of the capacitor C390, and inductors L121, L122, L123, L124 and C381 connected to the other end of the capacitor C368 after being connected in series, capacitors C369, C370, C372 and C373 connected in parallel to the inductors L121, L122, L123 and L123, respectively, capacitors C391, C393, C394 and C395 connected to the input terminals of the inductors L121, L122, L123 and L123, respectively, and connected to the ground at the other end, and capacitor C426 connected to the output terminal of the inductor L124 and connected to the ground at the other end; the other end of the capacitor C381 is connected to the RF5 pin of the RF switch chip U4 through the resistor R371.

Technical Field

The invention relates to a filter circuit, in particular to an LC switch filter bank segmented filter circuit.

Background

The LC switch filter is also called as a passive filter, adopts lumped mixed parameter design, and has the characteristics of small volume, light weight, stable and reliable performance and the like. The method is widely applied to harmonic suppression and background noise improvement, and is generally applicable to high-frequency signal filtering to reduce interference signals. The LC switch filter bank can carry out selective filtering in the circuit by section filtering, and the purpose of selective filtering is achieved by different signals according to the input of different frequencies.

The LC filter is called a passive filter, i.e. the device does not require an additional power supply. The LC filter is generally formed by combining a capacitor and an inductor, is connected with a harmonic source in parallel, and not only eliminates the filtering function, but also meets the requirement of reactive compensation. The filters are classified according to the pass band characteristics as: low pass filter, high pass filter, band pass filter. The most common function of the inductor in the circuit is to form an LC filter circuit together with a capacitor. The capacitor has the functions of blocking direct current and alternating current, and the inductor has the functions of blocking direct current, alternating current, low frequency and high frequency. If the direct current with a plurality of interference signals passes through the LC filter circuit, most of the alternating current interference signals are prevented by the inductor from being absorbed into magnetic induction and heat energy, the rest most of the alternating current interference signals are bypassed to the ground by the capacitor, the effect of the interference signals can be inhibited, and the direct current with relatively pure direct current can be obtained after the direct current is output.

The filtering frequency band of the traditional filter is fixed, the corresponding filtering frequency cannot be obtained according to different suppression requirements, and the filter configuration cost is high for debugging equipment requiring multiple frequency bands.

Disclosure of Invention

The invention aims to provide a segmented filter circuit of an LC switch filter bank, which mainly solves the problem that the filter frequency band of the existing filter is fixed and the corresponding filter frequency can not be obtained according to different suppression requirements.

In order to achieve the purpose, the invention adopts the following technical scheme:

an LC switch filter bank segmented filter circuit comprises 4 radio frequency switch chips U1, U2, U3 and U4 and filter circuits with frequency segments of 20-80MHz, 80-140MHz, 140 plus 250MHz, 250 plus 420MHz, 420 plus 710MHz, 710 plus 1220MHz and 1.2-2GHz respectively;

the filter circuit with the frequency segments of 80-140MHz, 140-250MHz and 250-420MHz is connected between the two radio frequency switch chips U1 and U2, the circuit topological structures are the same, and the circuit element parameters are different;

the filter circuit with the frequency segments of 20-80MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz is connected between the other two radio frequency switch chips U3 and U4; the radio frequency switch chips U1 and U3 are connected.

Further, the radio frequency switch chips U1 and U2 are HMC24LP 3; the filter circuit with the frequency band of 80-140MHz comprises a resistor R336 connected with an RF1 pin of a radio frequency switch chip U1, a resistor R337 connected with an RF4 pin of a switch chip U2, and a plurality of capacitors and LC filter circuits which are alternately arranged and connected between the resistor R336 and the resistor R337.

Furthermore, the model of the radio frequency switch chip U3 is XND42482MQI, and the model of the radio frequency switch chip U4 is HMC252AQS 24E; the RF8 pin of the radio frequency switch chip U3 is connected with the RFC pin of the radio frequency switch chip U1 through a capacitor C190.

Further, the filter circuit with the frequency band of 20-80MHz includes a resistor R672 connected to an RF4 pin of a radio frequency switch chip U3, inductors L200, L201, L204 with one end connected to the other end of the resistor C672 after being connected in series, capacitors C668, C669, C670 connected in parallel to two ends of the inductors L200, L201, L204, respectively, capacitors C676, C678, C675 with one end connected to input ends of the inductors L200, L201, L204, respectively, and with the other end grounded, an inductor L211 with one end connected to an output end of the inductor L204 and with the other end grounded, a capacitor C674 connected in parallel to two ends of the inductor L211, a capacitor C673 with one end connected to an output end of the inductor L204, an inductor L218 with one end connected to the other end of the capacitor C673 and with the other end grounded, and a capacitor C671 connected to a common terminal of the capacitors C673 and L218; the other end of the capacitor C671 is connected to the RF2 pin of the RF switch chip U4 through a resistor R345.

Further, the filter circuit with the frequency band of 420-710MHz comprises a resistor R372 connected to the RF6 pin of the RF switch chip U3, a capacitor C427 connected to the other end of the resistor R372, an inductor L129 and a capacitor C453 connected to the other end of the capacitor C427, inductors L128 and L130 connected to the other end of the capacitor C453, a capacitor C520 connected in parallel to both ends of the inductor L128, an inductor L134 and a capacitor C490 connected to the other end of the inductor L128, an inductor L139 and a low-pass filter F166 connected to the other end of the capacitor C490, and a capacitor C459 connected to the other end of the low-pass filter F166, wherein the other end of the capacitor C459 is connected to the RF4 pin of the RF switch chip U4 via a resistor R373; the other ends of the inductors L129, L130, L134, and L139 are grounded.

Further, the filter circuit with the frequency band of 710-1220MHz comprises a resistor R374 connected to the RF5 pin of the RF switch chip U3, a capacitor C524 connected to the other end of the resistor R374, a low-pass filter F154 connected to the other end of the capacitor C524, an inductor L142 and a capacitor C526 of a capacitor C459 connected to the other end of the low-pass filter F154, inductors L191 and L141 connected to the other end of the capacitor C526, a capacitor C644 connected in parallel to both ends of the inductor L141, an inductor L197 and a capacitor C628 connected to the other end of the inductor L141, an inductor L198 and a low-pass filter F155 connected to the other end of the capacitor C628, and a capacitor C527 connected to the other end of the low-pass filter F155, wherein the other end of the capacitor C527 is connected to the RF3 pin of the RF switch chip U4 through the resistor R375; the other ends of the inductors L142, L191, L197 and L198 are grounded.

Further, the filter circuit with the frequency band of 1.2-2GHz includes a resistor R370 connected to the RF7 pin of the RF switch chip U3, a capacitor C362 connected to the other end of the resistor R370, a capacitor C363 and an inductor L125 connected to the other end of the capacitor C362, a capacitor C384 connected to the other end of the inductor L125 and having the other end grounded, a capacitor C364 and an inductor L126 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L126 and having the other end grounded, a capacitor C369 and an inductor L127 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L127 and having the other end grounded, a capacitor C368 connected to the other end of the capacitor C390, inductors L121, L122, L123, L124, and a capacitor C381 connected to the other end of the capacitor C368 after series connection, and capacitors C373, C372, C370 and C372, capacitors C391, C393, C394, and C395 having one ends respectively connected to the input ends of the inductors L121, L122, L123, and L123 and the other ends grounded, and a capacitor C426 connected to the output end of the inductor L124 and the other end grounded; the other end of the capacitor C381 is connected to the RF5 pin of the RF switch chip U4 through the resistor R371.

Compared with the prior art, the invention has the following beneficial effects:

the invention can select the corresponding filtering frequency band through the radio frequency switch by setting the filtering circuit with multiple frequency bands. The technology is convenient to debug in a low frequency band, can call corresponding indexes according to different suppression requirements, is low in cost, can realize the splitting of wide frequency harmonic into multiple sections of narrow-band frequencies through switch selection, realizes the suppression of harmonic frequency through an LC filter, can be flexible and flexible, realizes the segmentation selection according to the actual requirements of the user, and can be applied to various scenes. Reduce the debugging configuration cost of the filter.

Drawings

FIG. 1 is a schematic diagram of a filter circuit with frequency bands of 80-140MHz, 140-250MHz, and 250-420MHz according to the present invention.

Fig. 2 is a schematic circuit diagram of the rf switch chip U3 according to the present invention.

Fig. 3 is a schematic circuit diagram of the rf switch chip U4 according to the present invention.

FIG. 4 is a schematic diagram of a filter circuit of the present invention with a frequency range of 20-80 MHz.

FIG. 5 is a schematic diagram of the filter circuit of the present invention with the frequency band of 710-1220 MHz.

FIG. 6 is a schematic diagram of the filter circuit of the invention with a frequency band of 420-710 MHz.

FIG. 7 is a schematic diagram of a filter circuit with a frequency band of 1.2-2GHz according to the invention.

Detailed Description

The invention will be further described with reference to the following description and examples, which include but are not limited to the following examples.

Examples

As shown in FIGS. 1 to 7, the LC switch filter bank segmented filter circuit disclosed in the present invention comprises 4 RF switch chips U1, U2, U3 and U4 and filter circuits with frequency segments of 20-80MHz, 80-140MHz, 140-250MHz, 250-420MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz, respectively. When the frequency band filtering circuit is used, the required frequency band circuit is switched on according to requirements, and then the corresponding filtered signal can be obtained.

In this embodiment, the filter circuit with the frequency band of 80-140MHz, 140-250MHz and 250-420MHz is connected between the two rf switch chips U1 and U2, and the circuit topology is the same, and the circuit element parameters are different; that is, the inductance value and the capacitance value in the circuit are different, and the specific parameter size can be obtained through calculation, debugging and calculation. The radio frequency switch chips U1 and U2 are HMC24LP 3; the filter circuit with the frequency band of 80-140MHz comprises a resistor R336 connected with an RF1 pin of a radio frequency switch chip U1, a resistor R337 connected with an RF4 pin of a switch chip U2, and a plurality of capacitors and LC filter circuits which are alternately arranged and connected between the resistor R336 and the resistor R337.

The filter circuit with the frequency segments of 20-80MHz, 420-710MHz, 710-1220MHz and 1.2-2GHz is connected between the other two radio frequency switch chips U3 and U4; the radio frequency switch chips U1 and U3 are connected.

In this embodiment, the model of the rf switch chip U3 is XND42482MQI, and the model of the rf switch chip U4 is HMC252AQS 24E; the RF8 pin of the radio frequency switch chip U3 is connected with the RFC pin of the radio frequency switch chip U1 through a capacitor C190.

In this embodiment, the filter circuit with a frequency band of 20-80MHz includes a resistor R672 connected to an RF4 pin of an RF switch chip U3, inductors L200, L201, and L204 connected in series with one end thereof connected to the other end of the resistor C672, capacitors C668, C669, and C670 connected in parallel to both ends of the inductors L200, L201, and L204, capacitors C676, C678, and C675 connected in series with input ends of the inductors L200, L201, and L204, respectively, and grounded at the other end thereof, an inductor L211 connected in parallel to an output end of the inductor L204 and grounded at the other end thereof, a capacitor C674 connected in parallel to both ends of the inductor L211, a capacitor C673 connected to an output end of the inductor L204, an inductor L218 connected in parallel with one end thereof connected to the other end of the capacitor C673 and grounded at the other end thereof, and a capacitor C671 connected to a common terminal of the capacitors C673 and L218; the other end of the capacitor C671 is connected to the RF2 pin of the RF switch chip U4 through a resistor R345.

In this embodiment, the filter circuit with the frequency band of 420-710MHz includes a resistor R372 connected to the RF6 pin of the RF switch chip U3, a capacitor C427 connected to the other end of the resistor R372, an inductor L129 and a capacitor C453 connected to the other end of the capacitor C427, inductors L128 and L130 connected to the other end of the capacitor C453, a capacitor C520 connected in parallel to both ends of the inductor L128, an inductor L134 and a capacitor C490 connected to the other end of the inductor L128, an inductor L139 and a low pass filter F166 connected to the other end of the capacitor C490, and a capacitor C459 connected to the other end of the low pass filter F166, wherein the other end of the capacitor C459 is connected to the RF4 pin of the RF switch chip U4 via a resistor R373; the other ends of the inductors L129, L130, L134, and L139 are grounded.

In this embodiment, the filter circuit with a frequency band of 710-1220MHz includes a resistor R374 connected to the RF5 pin of the RF switch chip U3, a capacitor C524 connected to the other end of the resistor R374, a low-pass filter F154 connected to the other end of the capacitor C524, an inductor L142 and a capacitor C526 of a capacitor C459 connected to the other end of the low-pass filter F154, inductors L191 and L141 connected to the other end of the capacitor C526, a capacitor C644 connected in parallel to both ends of the inductor L141, an inductor L197 and a capacitor C628 connected to the other end of the inductor L141, an inductor L198 and a low-pass filter F155 connected to the other end of the capacitor C628, and a capacitor C527 connected to the other end of the low-pass filter F155, where the other end of the capacitor C527 is connected to the RF3 pin of the RF switch chip U4 via the resistor R375; the other ends of the inductors L142, L191, L197 and L198 are grounded.

In this embodiment, the filter circuit with a frequency band of 1.2-2GHz includes a resistor R370 connected to an RF7 pin of an RF switch chip U3, a capacitor C362 connected to the other end of the resistor R370, a capacitor C363 and an inductor L125 connected to the other end of the capacitor C362, a capacitor C384 connected to the other end of the inductor L125 and grounded at the other end, a capacitor C364 and an inductor L126 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L126 and grounded at the other end, a capacitor C369 and an inductor L127 connected to the other end of the capacitor C363, a capacitor C389 connected to the other end of the inductor L127 and grounded at one end, a capacitor C368 connected to the other end of the capacitor C390, inductors L121, L122, L123, L124, and a capacitor C381 connected to the other end of the capacitor C368 after being connected in series, and capacitors C370, L123, and C370 connected in parallel to the inductors L121, L122, L123, and L123, respectively, C372 and C373, capacitors C391, C393, C394 and C395 connected to the input terminals of the inductors L121, L122, L123 and L123, respectively, and grounded at the other end, and a capacitor C426 connected to the output terminal of the inductor L124 and grounded at the other end; the other end of the capacitor C381 is connected to the RF5 pin of the RF switch chip U4 through the resistor R371.

In addition, in the invention, power filters are arranged at the power supply ends of the radio frequency switch chips U1, U2, U3 and U4, so that stable power supply to the radio frequency chips is realized, and the circuit works more stably.

Through the design, the invention can select the corresponding filtering frequency band through the radio frequency switch by setting the filtering circuit with multiple frequency bands. The technology is convenient to debug in a low frequency band, can call corresponding indexes according to different suppression requirements, is low in cost, can realize the splitting of wider frequency harmonic waves into multiple sections of narrow-band frequencies through switch selection, realizes the suppression of harmonic frequencies through an LC filter, can be flexibly changed, realizes the segmentation selection according to the actual requirements, can be applied to various scenes, and reduces the debugging and configuration cost of the filter. Therefore, the invention has substantial features and advances over the prior art.

The above-mentioned embodiment is only one of the preferred embodiments of the invention, and should not be used to limit the scope of the invention, but all the modifications or additions made to the spirit and the scope of the main body of the invention, which still solve the technical problems consistent with the invention, should be included in the scope of the invention.