CN105322907A - A duplexing filter circuit and an implementation method - Google Patents

Abstract

The invention provides a duplexing filter circuit and an implementation method. A filter circuit between a Term 1 port and a Term 2 port is a reciprocal network, and the Term 1 port serves as an input port while the term 2 port serves as an output port and vice versa. A radio frequency signal RF1 is input from the Term 2 port and is output from the Term 1 port via high frequency capacitors; or the radio frequency signal RF1 is input from the Term 1 port and is output from the Term 2 port via the high frequency capacitors. A filter circuit between the Term 1 port and a Term 3 port is a reciprocal network, and the Term 1 port serves as an input port while the term 3 port serves as an output port and vice versa. A frequency signal RF2 is input from the Term 3 port and is output from the Term 1 port via high frequency inductors; or the frequency signal RF2 is input from the Term 1 port and is output from the Term 3 port via the high frequency inductors. For high frequency circuits within the short-wave and ultrashort-wave frequency range, two paths of radio frequency signals with different frequencies can be isolated from each other and share transmitting and receiving antennas; if the power of any one path of radio frequency signals is attenuated by more than 60dB in the frequency range of the other path of radio frequency signals, the isolation between the two paths of radio frequency signals exceeds 60dB.

Description

A kind of diplex filter circuit and implementation method

Technical field

Circuit of the present invention relates to a kind of diplex filter circuit for two-way radiofrequency signal mutually isolated common transmit-receive antenna and implementation method.

Background technology

Under normal conditions, radio-frequency filter has two ports, and one is signal input, and another is signal output, and the impedance of two ports is all mated at 50 ohm.When a high pass filter and a low pass filter are connected in parallel by needs, when forming a kind of duplexer filter for the mutually isolated common transmit-receive antenna of two-way radiofrequency signal, the common port of two parallel filters can not be connected directly between together, and will by just linking together after suitable impedance matching.When RF signal power is very large, can make duplexer filter by cavity resonator, when radiofrequency signal is smaller, available discrete component builds filter circuit.Existing duplexer cavity body filter common configuration is comparatively large, and cost is also higher simultaneously, once circuit parameter requires change, need re-start debugging, versatility aspect Shortcomings.Also have the duplexer by two logical LC filter compositions of band, shortcoming is that circuit is comparatively complicated, and design difficulty is also larger.

Summary of the invention

In view of the deficiency that prior art exists, the invention provides a kind of diplex filter circuit and implementation method, the basic design scheme using discrete component to make duplexer filter, be mainly used in shortwave and ultrashort wave frequency range, radiofrequency signal RF1 frequency range is higher, radiofrequency signal RF2 frequency range is lower, and the frequency bandwidth of the two is variable, can be adjusted by the value of discrete component.

For achieving the above object, the technical scheme taked is in the present invention: a kind of diplex filter circuit and implementation method, is characterized in that: described diplex filter circuit is by Term1 port, Term2 port, Term3 port and high frequency capacitance C1, C2, C3, C4, C5, C6, C7, C8, C9 and high-frequency inductor L1, L2, L3, L4, L5, L6, L7, L8, L9 forms, and one end of described Term2 port is successively by high frequency capacitance C5, C4, C3, C2, C1, high-frequency inductor L5, L6, L7, L8, L9 connects one end of Term3 port, the other end ground connection respectively of described Term2 port and Term3 port, and the link of high frequency capacitance C1 and high-frequency inductor L5 passes through Term1 port ground connection, high frequency capacitance C5, the link of C4 passes through high-frequency inductor L4 ground connection, high frequency capacitance C4, the link of C3 passes through high-frequency inductor L3 ground connection, high frequency capacitance C3, the link of C2 passes through high-frequency inductor L2 ground connection, high frequency capacitance C2, the link of C1 passes through high-frequency inductor L1 ground connection, high-frequency inductor L5, the link of L6 passes through high frequency capacitance C6 ground connection, high-frequency inductor L6, the link of L7 passes through high frequency capacitance C7 ground connection, high-frequency inductor L7, the link of L8 passes through high frequency capacitance C8 ground connection, high-frequency inductor L8, the link of L9 is by high frequency capacitance C9 ground connection,

Implementation method is: the filter circuit between Term1 port and Term2 port is reciprocal network, can input/output port each other, radiofrequency signal RF1 inputs from Term2 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF1 through high frequency capacitance C5, C4, C3, C2, C1 successively, export from Term2 port through high frequency capacitance C1, C2, C4, C3, C5 successively;

Filter circuit between Term1 port and Term3 port is reciprocal network, can input/output port each other, radiofrequency signal RF2 inputs from Term3 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF2 through high-frequency inductor L9, L8, L7, L6, L5 successively, export from Term3 port through high-frequency inductor L5, L6, L7, L8, L9 successively;

Filter circuit between Term1 port and Term2 port is Chebyshev's high pass filter, the high frequency capacitance of series connection has the effect of filtering low frequency signal, high-frequency inductor in parallel also can filtering low frequency signal, by the filtering step by step of high frequency capacitance and high-frequency inductor, reach the object of filtering low frequency signal; Filter circuit between Term1 port and Term3 port is chebyshev low-pass filter, the high-frequency inductor of series connection has the effect of filtering high-frequency signal, high frequency capacitance in parallel also can filtering high-frequency signal, by the filtering step by step of high-frequency inductor and high frequency capacitance, reach the object of filtering high-frequency signal.

The invention has the beneficial effects as follows: for the high-frequency circuit in shortwave and ultrashort wave frequency range, the mutually isolated common transmit-receive antenna of the radiofrequency signal of two-way different frequency can be enable, the power of any road radiofrequency signal is attenuated more than 60dB in the frequency range of another road radiofrequency signal, and the isolation between two-way radiofrequency signal is more than 60dB.Circuit volume is little, and implementation method is simple, flexible, needs the exponent number that can also increase or reduce filter, design very convenient according to index.

Accompanying drawing explanation

Fig. 1 is circuit diagram of the present invention;

Fig. 2 is frequency response simulation curve figure.

Embodiment

As shown in Figure 1, a kind of diplex filter circuit, is made up of Term1 port, Term2 port, Term3 port and high frequency capacitance C1, C2, C3, C4, C5, C6, C7, C8, C9 and high-frequency inductor L1, L2, L3, L4, L5, L6, L7, L8, L9.

Circuit connects, one end of Term2 port is successively by high frequency capacitance C5, C4, C3, C2, C1, high-frequency inductor L5, L6, L7, L8, L9 connects one end of Term3 port, the other end ground connection respectively of Term2 port and Term3 port, the link of high frequency capacitance C1 and high-frequency inductor L5 is by Term1 port ground connection, high frequency capacitance C5, the link of C4 is by high-frequency inductor L4 ground connection, high frequency capacitance C4, the link of C3 is by high-frequency inductor L3 ground connection, high frequency capacitance C3, the link of C2 is by high-frequency inductor L2 ground connection, high frequency capacitance C2, the link of C1 is by high-frequency inductor L1 ground connection, high-frequency inductor L5, the link of L6 is by high frequency capacitance C6 ground connection, high-frequency inductor L6, the link of L7 is by high frequency capacitance C7 ground connection, high-frequency inductor L7, the link of L8 is by high frequency capacitance C8 ground connection, high-frequency inductor L8, the link of L9 is by high frequency capacitance C9 ground connection.

A kind of implementation method of diplex filter circuit is: the filter circuit between Term1 port and Term2 port is reciprocal network, can input/output port each other, radiofrequency signal RF1 inputs from Term2 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF1 through high frequency capacitance C5, C4, C3, C2, C1 successively, export from Term2 port through high frequency capacitance C1, C2, C4, C3, C5 successively;

Filter circuit between Term1 port and Term3 port is reciprocal network, can input/output port each other, radiofrequency signal RF2 inputs from Term3 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF2 through high-frequency inductor L9, L8, L7, L6, L5 successively, export from Term3 port through high-frequency inductor L5, L6, L7, L8, L9 successively;

Filter circuit between Term1 port and Term2 port is Chebyshev's high pass filter, the high frequency capacitance of series connection has the effect of filtering low frequency signal, high-frequency inductor in parallel also can filtering low frequency signal, by the filtering step by step of high frequency capacitance and high-frequency inductor, reach the object of filtering low frequency signal; Filter circuit between Term1 port and Term3 port is chebyshev low-pass filter, the high-frequency inductor of series connection has the effect of filtering high-frequency signal, high frequency capacitance in parallel also can filtering high-frequency signal, by the filtering step by step of high-frequency inductor and high frequency capacitance, reach the object of filtering high-frequency signal.

As shown in Figure 2, assuming that two-way radio frequency signal frequency is respectively 100MHz and 200MHz in duplexer, filter circuit between Term1 port and Term2 port is greater than 80dB for the suppression of 100MHz signal, for the suppression of 200MHz signal close to 0dB, is almost harmless.

Filter circuit between Term1 port and Term3 port is greater than 80dB for the suppression of 200MHz signal, for the suppression of 100MHz signal close to 0dB, is almost harmless.So this duplex filter structure can make two paths of signals respectively normal work and mutually isolated.

Claims (1)

1. diplex filter circuit and an implementation method, is characterized in that: described diplex filter circuit is by Term1 port, Term2 port, Term3 port and high frequency capacitance C1, C2, C3, C4, C5, C6, C7, C8, C9 and high-frequency inductor L1, L2, L3, L4, L5, L6, L7, L8, L9 forms, and one end of described Term2 port is successively by high frequency capacitance C5, C4, C3, C2, C1, high-frequency inductor L5, L6, L7, L8, L9 connects one end of Term3 port, the other end ground connection respectively of described Term2 port and Term3 port, and the link of high frequency capacitance C1 and high-frequency inductor L5 passes through Term1 port ground connection, high frequency capacitance C5, the link of C4 passes through high-frequency inductor L4 ground connection, high frequency capacitance C4, the link of C3 passes through high-frequency inductor L3 ground connection, high frequency capacitance C3, the link of C2 passes through high-frequency inductor L2 ground connection, high frequency capacitance C2, the link of C1 passes through high-frequency inductor L1 ground connection, high-frequency inductor L5, the link of L6 passes through high frequency capacitance C6 ground connection, high-frequency inductor L6, the link of L7 passes through high frequency capacitance C7 ground connection, high-frequency inductor L7, the link of L8 passes through high frequency capacitance C8 ground connection, high-frequency inductor L8, the link of L9 is by high frequency capacitance C9 ground connection,

Implementation method is: the filter circuit between Term1 port and Term2 port is reciprocal network, can input/output port each other, radiofrequency signal RF1 inputs from Term2 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF1 through high frequency capacitance C5, C4, C3, C2, C1 successively, export from Term2 port through high frequency capacitance C1, C2, C4, C3, C5 successively;

Filter circuit between Term1 port and Term3 port is reciprocal network, can input/output port each other, radiofrequency signal RF2 inputs from Term3 port, input from Term1 port from the output of Term1 port or radiofrequency signal RF2 through high-frequency inductor L9, L8, L7, L6, L5 successively, export from Term3 port through high-frequency inductor L5, L6, L7, L8, L9 successively;

Filter circuit between Term1 port and Term2 port is Chebyshev's high pass filter, the high frequency capacitance of series connection has the effect of filtering low frequency signal, high-frequency inductor in parallel also can filtering low frequency signal, by the filtering step by step of high frequency capacitance and high-frequency inductor, reach the object of filtering low frequency signal; Filter circuit between Term1 port and Term3 port is chebyshev low-pass filter, the high-frequency inductor of series connection has the effect of filtering high-frequency signal, high frequency capacitance in parallel also can filtering high-frequency signal, by the filtering step by step of high-frequency inductor and high frequency capacitance, reach the object of filtering high-frequency signal.