CN211209677U

CN211209677U - Low-pass filter with small dynamic high out-of-band rejection

Info

Publication number: CN211209677U
Application number: CN201921977707.2U
Authority: CN
Inventors: 李琛; 李平; 项玮; 曹狄峰
Original assignee: CETC 43 Research Institute
Current assignee: CETC 43 Research Institute
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2020-08-07
Anticipated expiration: 2029-11-15

Abstract

The utility model discloses a low pass filter of high outband of little fluctuation can solve and reduce the undulant technical problem of passband when improving the outband suppression. The filter comprises an attenuation network, a 13-order low-pass filter network and an all-pass filter network which are connected in sequence; the 13 th-order low-pass filter adopts a resonant absorption type structure. Full pass filter network plays undulant compensation and group delay compensation effect, and concrete electric capacity, inductance, resistance parameter can adjust the use according to actual need. A low pass filter of high outband suppression of little fluctuation, this merit divides utensil to have that the passband is undulant little, the outband suppression is high, advantage that group delay is little. The method has the advantages of high out-of-band rejection, effective resistance to signal interference, small passband fluctuation and capability of improving the gain stability of the receiver. The circuit has the advantages of simple structure, low cost and good application prospect.

Description

Low-pass filter with small dynamic high out-of-band rejection

Technical Field

The utility model relates to a signal filtering handles technical field, concretely relates to low pass filter of high outband suppression of little fluctuation.

Background

With the development of communication technology, signal transmission distances are farther and farther, signal interference is enhanced, and the requirements on out-of-band rejection of filters are higher and higher. At present, the known filter is obtained by engineering transformation of mathematical models such as Butterworth, Chebyshev, ellipse and the like, the improvement of out-of-band rejection requires the increase of circuit order, the size of the filter is increased, the process manufacturing difficulty and the cost are increased, the passband fluctuation is increased, and the gain stability of a receiver is reduced.

SUMMERY OF THE UTILITY MODEL

The utility model provides a low pass filter of high outband of little fluctuation can solve and reduce the undulant technical problem of passband when improving the outband and suppression.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a low-pass filter with small fluctuation and high out-of-band rejection comprises an attenuation network, a 13-order low-pass filter network and an all-pass filter network which are sequentially connected;

further, the 13 th order low-pass filter adopts a resonant absorption type structure.

Further, the attenuation network comprises a capacitor C1, an inductor L1 and a resistor R1;

one ends of the capacitor C1 and the inductor L1 are grounded, the other ends of the capacitor C1 and the inductor L1 are connected with one end of the resistor R1, and the other end of the resistor R1 forms an output end of the attenuation network and is connected with an input end of the 13-order low-pass filter network.

Further, the 13 th order low pass filter network comprises inductors L2, L3, L4, L5, L6 and L7 which are connected in series in sequence;

capacitors C4 and C8 are respectively connected in parallel at two ends of the inductors L3 and L6;

one end of each of the inductors L2, L3, L4, L5, L6 and L7 is further connected to one end of each of capacitors C2, C3, C5, C6, C7 and C9, the other end of each of the inductors L7 and L is connected to one end of a capacitor C10, the other ends of the capacitors C2, C3, C5, C6, C7, C9 and C10 are all connected to ground, one end of each of the inductors L2 is used as an input end of a 13-step low-pass filter network and is connected to an attenuation network, and the other end of each of the inductors L7 is used as an output end of the 13-step low-pass filter network and is connected to an input end of an all-pass filter network.

Further, the all-pass filter network comprises capacitors C11, C12 connected in series;

one end of the capacitor C11 and one end of the capacitor C12 are further connected with one end of an inductor L9, the other end of the inductor L9 is connected with one end of a capacitor C13, and the other end of the capacitor C13 is connected with ground;

the other end of the capacitor C11 is connected to the inductor L8, the other end of the capacitor C12 is connected to the other end of the inductor L8, one end of the inductor L8 is connected to the 13 th-order low-pass filter network as the input end of the all-pass filter network, and the other end of the inductor L8 is connected to the output end of the all-pass filter network.

Further, the cut-off frequency of the 13 th-order low-pass filter is 1210 MHz.

According to the above technical scheme, the utility model discloses a low pass filter of high outband suppression of small fluctuation is according to the interference signal frequency of the operating frequency of receiver, the utility model discloses a low pass filter, the passing frequency is at DC ~ 1210MHz, and 1420MHz ~ 5000MHz within range is by the filtering by a wide margin, can avoid out of band signal to disturb, guarantees signal reception, 13 order low pass filter network's cut-off frequency is 1210MHz, the attenuation network plays undulant compensation effect, the all-pass filter network plays undulant compensation and group delay compensation effect, and concrete electric capacity, inductance, resistance parameter can adjust the use according to actual need.

A low pass filter of high outband suppression of little fluctuation, this merit divides utensil to have that the passband is undulant little, the outband suppression is high, advantage that group delay is little. The method has the advantages of high out-of-band rejection, effective resistance to signal interference, small passband fluctuation and capability of improving the gain stability of the receiver. The circuit has the advantages of simple structure, low cost and good application prospect.

Drawings

Fig. 1 is a schematic circuit diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.

As shown in fig. 1, the low-pass filter with small fluctuation and high out-of-band rejection in this embodiment includes an attenuation network, a 13 th order low-pass filter network, and an all-pass filter network, where the attenuation network is connected to the 13 th order low-pass filter network, and the 13 th order low-pass filter network is connected to the all-pass filter network.

The 13-order low-pass filter network adopts a resonance absorption structure, so that the out-of-band rejection degree of the filter is improved.

The attenuation network comprises a capacitor C1, an inductor L1 and a resistor R1, one ends of the capacitor C1 and the inductor L1 are grounded, the other ends of the capacitor C1 and the inductor L1 are connected with one end of the resistor R1, and the other end of the resistor R1 forms an input end of the attenuation network and an output end of the attenuation network is connected with an input end of the 13-order low-pass filter network.

The 13-order low-pass filter network comprises inductors L2, L3, L04, L15, L26 and L37 which are connected in series, wherein the other end of the previous inductor is connected with one end of the next inductor, two ends of the inductors L43 and L56 are respectively connected with capacitors C4 and C8 in parallel, one ends of the inductors L62, L3, L4, L5, L6 and L7 are respectively connected with one ends of capacitors C2, C3, C5, C6, C7 and C9, the other end of the inductor L7 is connected with one end of a capacitor C10, the other ends of the capacitors C2, C3, C5, C6, C7, C9 and C10 are connected with the ground, one end of the inductor L2 is connected with the attenuation network as the input end of the 13-order low-pass filter network, and the other end of the inductor L7 is connected with the input end of the full-pass filter network as the output end of the 13-order low-pass filter network.

The all-pass filter network comprises capacitors C11 and C12 which are connected in series, the other end of a capacitor C11 is connected with one end of a capacitor C12, the other end of the capacitor C11 and one end of the capacitor C12 are also connected with one end of an inductor L9, the other end of the inductor L9 is connected with one end of the capacitor C13, the other end of the capacitor C13 is connected with the ground, one end of the capacitor C11 is connected with an inductor L8, the other end of the capacitor C12 is connected with the other end of an inductor L8, one end of the inductor L8 serves as an input end of the all-pass filter network and is connected with a 13-step low-pass filter network, and the other end of the inductor L8 serves as an output end of the all-pass filter network.

According to the operating frequency's of receiver interfering signal frequency, the utility model discloses low pass filter, through the frequency at DC ~ 1210MHz, 1420MHz ~ 5000MHz within range is filtered by a wide margin, can avoid out of band signal interference, guarantees signal reception, 13 order low pass filter network's cut-off frequency is 1210MHz, the attenuation network plays undulant compensation effect, the all-pass filter network plays undulant compensation and group delay compensation effect, and concrete electric capacity, inductance, resistance parameter can adjust the use according to actual need.

According to the above technical scheme, the embodiment of the utility model provide a low pass filter of high outband suppression of little fluctuation, have high outband suppression, can effectively resist signal interference, the passband is undulant little, can improve receiver gain stability. The circuit has the advantages of simple structure, low cost and good application prospect.

The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. A low pass filter with low ripple high out-of-band rejection, characterized by: the filter comprises an attenuation network, a 13-order low-pass filter network and an all-pass filter network which are connected in sequence;

the 13 th-order low-pass filter adopts a resonant absorption type structure.

2. The low pass filter with small fluctuation and high out-of-band rejection of claim 1, wherein the attenuation network comprises a capacitor C1, an inductor L1, and a resistor R1;

3. The low pass filter with small dynamic high out-of-band rejection of claim 2, wherein said 13 th order low pass filter network comprises inductors L2, L3, L4, L5, L6, L7 connected in series;

4. The low-pass filter with small dynamic high out-of-band rejection of claim 3, wherein: the all-pass filter network comprises capacitors C11, C12 connected in series;

5. The low-pass filter with small dynamic high out-of-band rejection of claim 1, wherein: the cut-off frequency of the 13 th-order low-pass filter is 1210 MHz.