CN103346373A - Lumped-parameter broadband 180-degree coupler - Google Patents

Abstract

The invention relates to a lumped-parameter broadband 180-degree coupler which comprises four capacitors and four inductors, wherein the four capacitors and the three inductors form double circuits in a connecting mode. One end of another inductor is connected with a third connection point, the other end of the inductor is grounded, and therefore inductive coupling is formed to improve the working bandwidth of the coupler. A first connection point is connected with a first port, a second connection point is connected with a second port, and a fourth connection point is connected with a third port. The lumped-parameter broadband 180-degree coupler is small in number of elements in use, small in occupied area, low in achieving cost, capable of keeping excellent output amplitude balance degrees and phase balance degrees within a very wide frequency band range, and suitable for an existing hand type mobile radio-frequency wireless communication system.

Description

A kind of broadband 180 degree couplers of lumped parameter

Technical field

The present invention relates to the communication circuit elements technical field, particularly relate to a kind of broadband 180 degree couplers of lumped parameter.

Background technology

In Modern Communication System, in radio frequency and the microwave and millimeter wave circuit, as balance amplifier, image-reject mixer in balanced type frequency multiplier etc., usually needs to use 180 degree couplers.Especially in current mobile electron Communications Market, along with the development of multifrequency (multi-band) multimode (multi-mode) technology, the radio frequency transceiver that can satisfy various frequency ranges and communication standard simultaneously becomes present developing direction.As device important in the receive-transmit system, the demand of the 180 degree couplers in broadband is just constantly strengthened.At present popular 180 traditional degree couplers adopt microstrip structure mostly, as Marchand Ba Lun, 180 little band hybrid rings, the Lange coupler to etc.These are very big based on microstrip structures 180 degree couplers of electrical length shared area in the radio frequency band scope, have greatly increased area and the cost of radio system.Recently, some are reported in periodical to some extent based on 180 degree couplers of lump components and parts, as " Compact28-GHzsubharmonically pumpedresistivemixerMMICusingalumped-elementhigh-pass/ba nd-passbalun; " IEEE Microw.WirelessCompon.Lett., vol.15, no.2, pp.62-64, Feb.2005 and " Designofcompact 90oand180ocouplerswithharmonicsuppressionusinglumped-ele mentbandstopresonators; " IEEETrans.Microw.TheoryTech., vol.58, no.11, pp.2932-2939, Nov.2010. still these circuit can only provide very narrow frequency bandwidth (less than 10%), thereby limited its application greatly, especially in present mobile communication system.

Summary of the invention

The invention provides a kind of broadband 180 degree couplers of lumped parameter, it uses number of devices few, area occupied is little, and has wideer working band, thereby solved present broadband 180 technical problem that degree coupler area occupied is big and price is high, also solved the problem of 180 degree coupler bandwidth deficiencies of lumped device simultaneously.

The technical solution adopted for the present invention to solve the technical problems is: the broadband 180 degree couplers that a kind of lumped parameter is provided, comprise four electric capacity and three inductance, four electric capacity are respectively first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity, three inductance are respectively first inductance, second inductance and the 3rd inductance, and an end of described first inductance and an end of first electric capacity all are connected in first tie point; One end of the other end of described first inductance and second electric capacity all is connected in second tie point; One end of one end of the other end of described second electric capacity, second inductance and an end of the 3rd electric capacity all is connected in the 3rd tie point; One end of the other end of described the 3rd electric capacity and the 3rd inductance is connected in the 4th tie point; One end of the other end of described the 3rd inductance and the 4th electric capacity is connected in the 5th tie point; The other end of the other end of the other end of described first electric capacity, second inductance and the 4th electric capacity is connected in the 6th tie point; Described first tie point connects first port; Described second tie point connects second port; Described the 3rd tie point links to each other with earth terminal; Described the 4th tie point connects the 3rd port.

Also be connected with the 4th inductance between described the 3rd tie point and the earth terminal.

Described first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity have identical capacitance.

Described first inductance has identical inductance value with the 3rd inductance.

The inductance value of described second inductance is half of inductance value of first inductance.

The inductance value of described the 4th inductance is the 1/n of the inductance value of first inductance, and wherein, n is proportionality constant.

Described proportionality constant is between 0.1 to 0.2.

The capacitance of described first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity is Wherein, Z _InBe the impedance of system input mouth, Z _OutBe the impedance of system input mouth, ω is operating frequency.

The inductance value of described first inductance and the 3rd inductance is Wherein, Z _InBe the impedance of system input mouth, Z _OutBe the impedance of system input mouth, ω is operating frequency.

Beneficial effect

Owing to adopted above-mentioned technical scheme, the present invention compared with prior art, have following advantage and good effect: the present invention adopts lumped-parameter element, can greatly dwindle area and cost than traditional little 180 degree couplers of being with, bandwidth of operation can be improved greatly compared to traditional lumped parameter 180 degree couplers, thereby the miniaturization of mobile radio system and the requirement of multiband can be satisfied.

Description of drawings

Fig. 1 is lumped parameter of the present invention broadband 180 degree coupler circuit topological structure schematic diagrames;

Fig. 2 is the strange mould topological structure schematic diagram of lumped parameter of the present invention broadband 180 degree coupler circuits (one side of something);

Fig. 3 is the even mould topological structure schematic diagram of lumped parameter of the present invention broadband 180 degree coupler circuits (one side of something);

Fig. 4 is the scattering parameter curve chart of lumped parameter of the present invention broadband 180 degree coupler circuit emulation;

Fig. 5 is the amplitude imbalance of (second port and the 3rd port) between the output port of the lumped parameter of the present invention broadband 180 degree coupler circuit emulation line chart of writing music;

Fig. 6 is the phase unbalance degree curve chart of (second port and the 3rd port) between the output port of lumped parameter of the present invention broadband 180 degree coupler circuit emulation.

Embodiment

Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used for explanation the present invention and be not used in and limit the scope of the invention.Should be understood that in addition those skilled in the art can make various changes or modifications the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims institute restricted portion equally.

A kind of broadband 180 degree couplers of lumped parameter, as shown in Figure 1, comprise four electric capacity and four inductance, be respectively first inductance L 1, second inductance L 2, the 3rd inductance L 3, the 4th inductance L 4, first capacitor C 1, second capacitor C 2, the 3rd capacitor C 3 and the 4th capacitor C 4.Wherein, an end of an end of described first inductance L 1 and first capacitor C 1 is connected in first tie point 01; One end of the other end of described first inductance L 1 and second capacitor C 2 is connected in second tie point 02; One end of one end of one end of the other end of described second capacitor C 2, second inductance L 2, the 3rd capacitor C 3 and the 4th inductance L 4 is connected in the 3rd tie point 03; The other end ground connection of described the 4th inductance L 4; One end of the other end of described the 3rd capacitor C 3 and the 3rd inductance L 3 is connected in the 4th tie point 04; One end of the other end of described the 3rd inductance L 3 and the 4th capacitor C 4 is connected in the 5th tie point 05; The other end of the other end of the other end of described first capacitor C 1, second inductance L 2 and the 4th capacitor C 4 is connected in the 6th tie point 06; Described first tie point 01 connects first port one; Described second tie point 02 connects second port 2; Described the 4th tie point 04 connects the 3rd port 3.Described the 4th inductance L 4 is connected across between the 3rd tie point 03 and the ground, and it is inductive coupled to form secondary, improves the working band bandwidth.

According to microwave network theory, employing parity mode method is analyzed circuit network topology as shown in fig. 1.Fig. 2 and Fig. 3 represent its strange mould and even moding circuit respectively.Suppose that first port is the network input port, second port is the straight-through port of network, and the 3rd port is the coupling port of network, and the 4th port is the isolated port of network.The scattering parameter matrix of parity mode circuit is respectively:

${\left[S\right]}_{\mathrm{odd}}=\left[\begin{array}{cc}{S}_{11}^o& S_{21}^o\\ S_{12}^o& S_{22}^o\end{array}\right]---1)$

${\left[S\right]}_{\mathrm{even}}=\left[\begin{array}{cc}{S}_{11}^e& S_{21}^e\\ S_{12}^e& S_{22}^e\end{array}\right]---2)$

Wherein Represent that strange mould energy injects from the j mouth, records energy at the i mouth; Represent that even mould energy injects from the j mouth, records energy at the i mouth.

Be expressed as strange mould signal from the energy of first port one reflection and the square root of first port one input energy ratio;

When being expressed as second port, 2 couplings, the strange forward transmission coefficient of mould signal from first port one to second port 2;

When being expressed as first port one coupling, strange mould signal is from the forward transmission coefficient of second port, 2 to first port ones;

Be expressed as strange mould signal from the energy of second port, 2 reflections and the square root of second port, 2 input energy ratio;

Be expressed as even mould signal from the energy of first port one reflection and the square root of first port one input energy ratio; When being expressed as second port, 2 couplings, the forward transmission coefficient of even mould signal from first port one to second port 2;

When being expressed as first port one coupling, even mould signal is from the forward transmission coefficient of second port, 2 to first port ones;

Be expressed as even mould signal from the energy of second port, 2 reflections and the square root of second port, 2 input energy ratio.

Can be obtained the scattering parameter of directional coupler by network theory:

$S_{11}=\frac{1}{2}(S_{11}^e+S_{11}^o)---3)$

$S_{21}=\frac{1}{2}(S_{11}^e-S_{11}^o)---4)$

$S_{31}=\frac{1}{2}(S_{21}^e-S_{21}^o)---5)$

$S_{41}=\frac{1}{2}(S_{21}^e+S_{21}^o)---6)$

The parameter that is optimized is:

$C=\frac{1}{\mathrm{\ω}\sqrt{2Z_{\mathrm{in}}{Z}_{\mathrm{out}}}}---7)$

$L=\frac{\sqrt{2Z_{\mathrm{in}}{Z}_{\mathrm{out}}}}{\mathrm{\ω}}---8)$

0.1＜n＜0.2 9)

Wherein, Z _InThe impedance of expression input port, Z _OutThe impedance of expression output port, ω ₀Expression coupler operating frequency.Proportionality constant n is between 0.1 and 0.2, and optimum value is about 0.15.

Suppose that input/output port is 50 ohmages, (thereby output inserts loss less than 1dB to the bandwidth of operation that is optimized, phase difference departs from 180 degree less than 2 degree between output port, amplitude difference is less than 0.5dB between output port) greater than 50%, and the bandwidth of operation of traditional lumped parameter 180 degree couplers is less than 10%.

First capacitor C 1, second capacitor C 2, the 3rd capacitor C 3 and the 4th capacitor C 4 have identical capacitance; First inductance L 1 has identical inductance value with the 3rd inductance L 3; The inductance value of second inductance L 2 is that first inductance L, 1 inductance value gets half; The inductance value of the 4th inductance L 4 is 15% of first inductance L 1.In the present embodiment, be example with the broadband 180 degree couplers of the lumped parameter of 2.45GHz, but be not limited only to the 180 degree couplers of 2.45GHz.According to formula 7), 8) and 9), the parameter value that obtains above-mentioned each components and parts is selected as follows:

The device name	Device value
		C1	0.9pF
C2	0.9pF
		C3	0.9pF
C4	0.9pF
		L1	4.7nH
L2	4.7nH
		L3	2.3nH
L4	0.7nH

In the present embodiment, first port one is input port, and second port 2 is straight-through port, and the 3rd port 3 is coupling port, the isolated port open circuit.

Accompanying drawing 4 is port reflection coefficient and transmission coefficient curves of each port of present embodiment.The implication of Sij is: energy injects from the j mouth, records energy at the i mouth.S ₁₁Be expressed as from the energy of first port one reflection and the square root of first port one input energy ratio; S ₂₁When being expressed as second port, 2 couplings, first port one is to the forward transmission coefficient of second port 2; S ₃₁When being expressed as the 3rd port 3 couplings, the forward transmission coefficient of first port one to the, three ports 3.Among Fig. 4 as can be seen, in the frequency range from 2.3GHz to 3.2GHz, S ₂₁And S ₃₁All less than 3.5dB, S11 is greater than 10dB.

Fig. 5 is the amplitude imbalance of (second port and the 3rd port) between the output port of lumped parameter broadband 180 degree coupler circuit emulation in the present embodiment line of writing music, the amplitude imbalance degree 2.2GHz in the 3.2GHz all less than 0.3dB.

Fig. 6 is the phase unbalance degree curve of (second port and the 3rd port) between the output port of lumped parameter broadband 180 degree coupler circuit emulation in the present embodiment, phase unbalance degree 2.2GHz in the 3.2GHz all less than 5 degree.

In sum, lumped parameter of the present invention broadband 180 degree couplers are compared with 180 traditional degree couplers, have following good effect:

1) compared to 180 degree couplers of the little band forms of tradition, lumped parameter of the present invention broadband 180 degree coupler areas are little, difficulty of processing is little, cost is low;

2) in a single day 180 degree couplers of traditional little band forms complete and just can not revise, and by contrast, lumped parameter of the present invention broadband 180 degree couplers use lamped element, have adjustable property;

3) compared to 180 degree couplers of traditional lumped parameter, lumped parameter of the present invention broadband 180 degree couplers have adopted the inductive coupled technology of secondary at the 3rd tie point place, have significantly improved bandwidth of operation.

Claims (9)

1. couplers are spent in the broadband 180 of a lumped parameter, comprise four electric capacity and three inductance, four electric capacity are respectively first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity, three inductance are respectively first inductance, second inductance and the 3rd inductance, it is characterized in that an end of described first inductance and an end of first electric capacity all are connected in first tie point; One end of the other end of described first inductance and second electric capacity all is connected in second tie point; One end of one end of the other end of described second electric capacity, second inductance and an end of the 3rd electric capacity all is connected in the 3rd tie point; One end of the other end of described the 3rd electric capacity and the 3rd inductance is connected in the 4th tie point; One end of the other end of described the 3rd inductance and the 4th electric capacity is connected in the 5th tie point; The other end of the other end of the other end of described first electric capacity, second inductance and the 4th electric capacity is connected in the 6th tie point; Described first tie point connects first port; Described second tie point connects second port; Described the 3rd tie point links to each other with earth terminal; Described the 4th tie point connects the 3rd port.

2. the broadband 180 degree couplers of lumped parameter according to claim 1 is characterized in that, also are connected with the 4th inductance between described the 3rd tie point and the earth terminal.

3. the broadband 180 degree couplers of lumped parameter according to claim 1 is characterized in that described first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity have identical capacitance.

4. the broadband 180 degree couplers of lumped parameter according to claim 1 is characterized in that described first inductance has identical inductance value with the 3rd inductance.

5. degree couplers in the broadband 180 of lumped parameter according to claim 1 is characterized in that, the inductance value of described second inductance is half of inductance value of first inductance.

6. the broadband 180 degree couplers of lumped parameter according to claim 2 is characterized in that the inductance value of described the 4th inductance is the 1/n of the inductance value of first inductance, and wherein, n is proportionality constant.

7. the broadband 180 degree couplers of lumped parameter according to claim 6 is characterized in that described proportionality constant is between 0.1 to 0.2.

8. the broadband 180 degree couplers of lumped parameter according to claim 1 is characterized in that the capacitance of described first electric capacity, second electric capacity, the 3rd electric capacity and the 4th electric capacity is

Wherein, Z _InBe the impedance of system input mouth, Z _OutBe the impedance of system input mouth, ω is operating frequency.

9. the broadband 180 degree couplers of lumped parameter according to claim 1 is characterized in that the inductance value of described first inductance and the 3rd inductance is Wherein, Z _InBe the impedance of system input mouth, Z _OutBe the impedance of system input mouth, ω is operating frequency.

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