JPH01208901A - Microwave integrated circuit - Google Patents

Abstract

PURPOSE:To easily realize a microwave integrated circuit with dense coupling by using other board than a board for an input/output circuit so as to constitute a dense coupling part in a directional coupler, etc. CONSTITUTION:Boards 1, 2 are connected by a connecting piece 3, and in this case, as required, a prescribed gap G depending on the coupling or a board with a low dielectric constant is clipped as a spacer to place the board 2 onto the board 1. The boards 1, 2 are fixed by using an adhesives, etc., at a position sufficiently parted from the line 4. A microwave power applied to a terminal 1' of a microwave transmission circuit comprising a ground conductor 7 and a microstrip line 4 passes through a coupling pattern 5. A desired coupling is obtained at a terminal 2' by selecting properly a thickness T of the coupling line board 2, a line width C of the coupling line patterns 5, 6 and the gap G from the surface of the input/output line board 1 up to the coupling line patterns 5, 6 on the coupling line board 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a microwave integrated circuit such as a directional coupler using ceramic or the like as a dielectric substrate.

[Prior art] Figure 3 (a) shows the direction using the conventional microstrip line shown in Figures 2.18 and 2.23 (b) published in "Microwave circuits for communication" edited by the Institute of Electronics and Communication Engineers. In the figure, 1 is a dielectric substrate such as ceramic, 4, 5.6 are microstrip lines formed on the substrate 1, 5, 6 are coupling line parts, and 4 is a coupling line. Railroad 5.6
This line connects the input/output terminals ■ to ■ of the directional coupler. 7 is a ground conductor.

(in Figure 3) is a type of 3 dB direction generator using the conventional microstrip line shown in Figure 2.25 of the above-mentioned "Microwave circuit for communication", and in the figure, Figure 3 (a) The same reference numerals indicate the same elements, and 11 is a wire connecting the coupling lines 5 and 6.

Next, the operation will be explained. In FIG. 3(a), when the microwave power applied to the terminal ■ of the microwave transmission line composed of the ground conductor 7 and the microstrip line 4 passes through the coupling line 5, a part of the power is coupled to the coupling line 6. Most of the remaining power is transmitted to terminal ■. Therefore, by appropriately selecting the gap G between the coupling lines 5, 6, the substrate thickness H, and the line width W, a desired amount of coupling can be obtained at the terminal (2).

Figure 3 (bl is an example of a 3 dB directional coupler. In such a tightly coupled directional coupler, the gap G between the coupling lines becomes extremely narrow in the structure shown in Figure 3 (8). This is not possible, so a structure as shown in FIG. 3(b) is adopted.

The operation is the same as in Fig. 3(a) except that the positions of terminal numbers ■ to ■ are different, and the amount of coupling from terminal ■ to ■ is 3 dB, so 3 dB is also transmitted to terminal ■. Ru.

[Problem to be solved by the invention]

Conventional directional couplers are configured as described above, so when close coupling is required, the gap between the coupling lines becomes very narrow, and unless the pattern accuracy is extremely high, it will not work as designed. It is difficult to obtain the amount of binding, and the productivity is poor.

In addition, since the gap is narrow, the power resistance is low, and since all of the coupling line sections are planar paths, there are problems such as a large area is required. Similar problems occur in microwave integrated circuits other than directional couplers, such as filters using coupled lines using microstrip lines.

This invention was made to solve the above-mentioned problems, and does not require precise control of the gap between coupled lines, has good productivity, has excellent power durability, and saves space. The aim is to obtain microwave integrated circuits such as narrow, directional couplers.

[Means to solve the problem]

The microwave integrated circuit according to the present invention is constructed by patterning the coupled line portions on both sides of a high dielectric substrate such as a ceramic having a predetermined thickness, and then patterning the coupling line portions on both sides of a high dielectric substrate made of ceramic or the like, and forming a predetermined space on the substrate patterned with the human output line. The input/output line and the coupling line part are connected to each other with an open space.

[Effect]

In the microwave integrated circuit according to the present invention, in order to realize a relatively tightly coupled coupler, the coupled line sections are formed on both sides of a high dielectric substrate having a predetermined thickness determined by the amount of coupling, etc. By using a thin dielectric substrate with high power resistance, it is possible to realize a tightly coupled circuit with a coupling amount of 3 dB or more, which was impossible with conventional microstrip lines, and by adjusting the gap width, it is possible to achieve the desired The amount of binding can be easily obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a microwave integrated circuit according to an embodiment of the present invention, here shown as being applied to a directional coupler.

In the figure, 1 is an input/output line substrate 1 (first substrate) made of ceramic or the like, 2 is a coupled line substrate (second substrate) also made of ceramic or the like, and 4 is formed on substrate 1. This is a microstrip line input/output circuit. 5.6
Reference numeral 3 indicates a coupling line portion pattern formed on both sides of the substrate 2 so as to face each other with the substrate in between, and 3 indicates four terminals ① and ③ constituted by the human output line 4 on the substrate 1.

(2) and (2) are connection pieces made of gold ribbons or the like that connect the four ends of each of the coupling lines 5.degree.6 formed on both sides of the substrate 2, respectively. 7 is a ground conductor of the substrate 1.

The substrate 1 and the substrate 2 are connected by a connecting piece 3, and if necessary, a predetermined gap G determined depending on the amount of coupling may be left, or a low dielectric constant substrate may be used as a spacer to place the substrate 2 on the substrate 1. let

For structural assembly of the substrate 1 and the substrate 2, they are fixed with adhesive (not shown) or the like at a position sufficiently distant from the line 4.

Next, the operation will be explained. In FIG. 1, when the microwave power applied to the terminal ■ of the microwave transmission circuit composed of the ground conductor 7 and the microstrip line 4 passes through the coupled line pattern 5, part of the power is transferred to the coupled line pattern 5. 6 and sent to terminal ■, and the remaining power is transmitted to terminal ■.

In this device, the thickness T of the coupled line substrate 2, the line width C of the coupled line patterns 5 and 6, and the coupled line pattern 5. By appropriately selecting the gap G up to 6, the desired amount of coupling can be obtained at the terminal (2).

Next, in order to obtain the desired amount of bonding, the thickness T of the substrate is determined.

The relationship between line width C, etc. will be explained.

- In a TEM mode directional coupler for boat fishing, the above relationships are explained by the following equations (1) to (4).

For formulas (1) to (4), McGraw-Hill (McG
Published by RAW-formerly LL) GL Mahtahai (
"Microwave Filters, Impedance Matching Networks and Coupling Structures" by G, L, M^TTHAEl) et al.
edance-Matching Networks+
and Coupling 5 structures”
)-hereinafter referred to as Reference Material 1-p, 778. SHC,1
See 3.02.

Zo = $ ... (2) Zo
is the characteristic impedance of the line connected to the input/output terminal of the coupler, and is assumed to be matched with the impedance of the input/output terminal of the coupler.

Zoe and Zoo are the even mode and odd mode impedances of the coupled line section, and the dimensions of each part are the required Z O
Calculated from the el Z ooO value.

Even mode, odd mode impedance Zoe, Zo
o and the capacity per unit length of the line in each mode]
Coe and Coo have the following relationship (Reference Material 1)
+ p, 182) e, /TT, Zoe= 376.6 g/Coe
...(5)5-Zoo= 376.68
/Coo = (6) Even mode and odd mode capacitance per unit length of a general parallel coupled line Coe/t, Co.

/ε is reference material 1. p, 191. Equation 5.05-24.
As shown in Equation 5.05-25 and Figure 5.05-11, it is expressed as the sum of various fringing capacitances and parallel plate capacitances.

In order to obtain a design formula for the configuration of the coupling portion according to the present invention, a description will be given below using FIG. 2.

FIG. 2(a) shows the even mode state of the coupling portion according to the present invention, and it can be seen that the capacitance Coe/l per unit length is given only by the fringing capacitance ICg/ε.

Coe/s = 2 Cg/8
(7) FIG. 2('b) shows the odd mode state, and it can be seen that the capacitance Coo/ε per unit length is expressed by a quadratic equation.

Coo/g= (Cop/g)+ (Ch/l>+2
(Cg /ε) ...(8) Next,
Fringing capacitance Cg/ε, Ch/ according to the configuration of the present invention
In order to obtain ε from the fringing capacitance calculated in Reference Material 1, the equivalent configuration diagrams for even mode and odd mode are shown in Figures 2 (C) and (d), and the coupling part conductor is A. , B, as shown in Figure 2 (C), Co
Since e/a is the capacitance between conductor A and ground conductor GND, fringing capacitance Cg/ε is the capacitance between conductor A and ground conductor GN.
Conductor A when a virtual image conductor C is set in a symmetrical position with D.

It can be seen that it is equal to the fringing capacity ItCfo'/a in the odd mode between 0 and 0. However, here, the gap G is assumed to be 0.

Cg/ε=Cfo'/ε...(
9) Since Coo/ε is the capacitance between the conductor A and the ground conductor GND as shown in Figure 2(d), the fringing capacitance Ch/# is the capacitance between the conductor A and the image conductor C in the even mode. It can be seen that the fringing capacitance is equal to Cfe'/ε.

Ch/ε=Cfe'/s
, , α in Fig. 2), the parallel plate capacitance Cop
It goes without saying that /ε is equal to Cp/ε in FIG. 2(d). The parallel plate capacity can be expressed as Cp/ε=2W/(b-t) using the parameters shown in Figure 2+d) (Reference Material 1, p. 191).

(71, By substituting equation (9) and αω into equation (8), Coe/l=2cg/1=2cfo'/l ・
・・αυCoo/e= (Cop/g)+ (Ch/
g)+2(Cg/ε) =(Cp/ε)+(Cfe'/ε)+'l(C
fo'/ε) ... (2) Figure 2 (C1
, (d) using the parameters t, S, b, Cf
e' /l+ Cfo' /l is p, 1 of reference material 1
It can be determined from Fig. 5.05-9.10 of 88.189.

Now that the design formula of the present invention has been determined, actual numerical calculations will be performed to examine the effective range of application of the present invention.

First, ceramic substrates (ε, = 9.8~1
An example of a trial calculation when configuring a 3 dB directional coupler using 0.2) is shown below. The characteristic impedance ZO is 50Ω.

(From the coupling degree of 3 dB corresponding to equation 11, C is the voltage coupling coefficient, so 3 (dB) = 201og+.C,',C=0.
708 (31, (from formula 41, Coe/e = 367.6/ (Zoe -5)
= 0.9737Coo/ a = 367.6/ (
Zoo ・lv:″) =5.7064 From the αυ formula, Coe/ε=2cg /g=2Cfo'/g,', C
fo ' / g #0.49 Here, F in Reference 1
ig, 5.05-10(a), Cfo'/ε
From the values of , the relationship between the parameters b, t, and s shown in FIG. 2(C) is determined. Here, the gap G is assumed to be O. Fig
, 5.05-10(a), Cfo'/g=0.
49 is obtained when t/b = O. Approximately s/b = 0
．． When 83t/b = 0.025, approximately s/b
>1.5, Cfo'/ε becomes constant.

Since 1 = 0 is impossible, if t / b = 0.025, for example, t = 0.006 (n + m), b = 0.2
5 (mm) and s > 0°38 (n+m), the above conditions can be satisfied.

Next, the (support) equation and Reference Material 1 Fig, 5.05-9
Find the value of W.

From the formula 0, Coo/l = (Cp /g) + (Cfe'
/g)+2(Cfo'/ε)=5.70
64,', (Cp /e') + (Cfe
'/g) = 4.7327 From the value of Coe/ε, s >
0.38, the thickness of the ceramic substrate is selected as 0.635 (mm), which is one of the standard materials, and s = 0.38.
635 X 2 =1.27.

t/b from Fig, 5.05-9 in Reference Material 1
= 0.025, s/b = 1.2710.25
=5.08>1.5, so Cfe'/g
=0.48. Therefore, Cp/ε= 4.7327
-0.48 = 4.2527Cp/ε=2W/(b-
t), W= (Cp/ε)・(b-t)/2=0.518
It is calculated as 1 (mm).

This concludes the description of one embodiment of the present invention. Next, other embodiments of the present invention will be described.

FIG. 4 shows an embodiment in which the present invention is applied to a three-section directional coupler. In the figure, the same reference numerals as in FIG. 1 indicate the same parts, and the relationships among the signal input/output terminals (1) to (2) are also the same as in FIG. The central CPL (C) portion is a tightly coupled portion, and the CPL (L) portions on both sides thereof are loosely coupled portions. The operation is explained below: 3 sections 3dB
It is similar to a directional coupler.

E CM (Electronic Counter
Measure) devices require various broadband microwave devices spanning one octave or more. Among these, the 3 dB directional coupler is an indispensable device as a hybrid circuit in the configuration of a balanced FET amplifier, etc., and there is a strong demand for a wider band.

The most well-known method for widening bandwidth is S in Reference Material 1.
Three-section directional couplers are known, as shown in EC, 13,03.

-For example, Reference 1, Table 13.03-
The present invention will be explained by calculating a three-section 3 dB directional coupler with a ripple of ±0.2 dB from Hp, 789).

Among the three sections, the coupling coefficient of the central coupler is Ta
From ble, C,=0.8405. 201ogC2
=1.51, so it is a 1.51 dB tightly coupled directional coupler.

+3), ((5) from equation 41, Coe/a = 376.6/(Zoe-(i) from equation (6)
= 0.69Coo/s =376.6/(Z
oo-fi) -8,01o1) From the formula, Coe/s = 2 Cfo'/t -0,6
9,',Cfo'/ε=0.34 t/b according to Fig. 5.05-10(a) of Reference Material 1.

Regardless of the value of s/b, Cfo'/g is approximately 0.
44 or more, and Cfo'/ε<0.44 cannot be realized. This is because a large value of ε=10.2 is used.

The major feature of this invention is that it achieves a low effective permittivity εaft in even mode, and in order to make this possible, in the present invention, between the coupling line tread board and the input/output line tread board, As shown in FIG. 2(a), a method of creating a gap G is adopted.

Generally, capacitance is inversely proportional to the distance between electrodes and proportional to dielectric constant. In addition, the fringing capacitance Cg in even mode is the capacitance of the space part (ε7=1) and the dielectric part (ε, =IO,2)
Assuming that the capacitances of
05 (Sho l11), bond line tread board thickness T = 0.12
Assuming that a standard ceramic substrate of 7 (+am) is used, the effective dielectric constant εmft is calculated backward so that the impedance Zoe in even mode is adjusted to a predetermined value.

t/b in Figure 2(C) is t/b from Figure 2(a).
b= t/ (T+ t) #0.038 At this time, according to Fig. 5.05-10 (a) of Reference Material 1,
When s/b≧1.5, approximately Cfo'/
t = 0°51, therefore, from formula 00, Coe/
a=2Cfo'/ε=1.02.

Substituting this value into equation (5) yields 1, °, and ε. tt ”4.725 If this value is substituted into formula 031, G/H1, that is, gap G
is required.

If the thickness of the input/output line board is H = 0.4 (a + m),
G=0.057 (nm).

Next, as with the 3 dB directional coupler, W can be calculated from equation (b) for the odd mode.

From formula (2) and Fig. 5.05-9 of Reference Material 1, Cfe'/ε=0.50. Cp /ε=6.5, so from Cp 丑2W/(b-t), W = 0.412
(mad) is obtained.

The above is an approximate design formula for explaining the present invention, and strictly speaking, it is necessary to consider the influence of the gap G when calculating the fringing capacitance Cfe'/ε.

Next, the couplers at both ends of the three-section directional coupler will be explained. According to Table 13.03-1 of Reference Material 1, C, = 0.18367. 201og Cs=
The loose coupling directionality is 14.72 (dB), and when calculated using this method, Cp/a<Q, making the configuration impossible. Therefore, the loosely-coupled intertwined troughs are designed using ordinary couplers using microstrip lines.

Finally, the length of the coupling line will be explained.

In FIG. 2(a), the capacitance Coe in the even mode is made up of only a fringing capacitance of 1 cg, so the wavelength is calculated using the effective dielectric constant given by the α equation.

As can be seen in Figure 2(b), the capacitance Coo in the odd mode is composed of Cg and Ch, which are affected by the gap G, and Cop, which is not affected by the gap G. This is considered to be between the wavelength of the odd mode.

Therefore, the line length of the coupled portion as a coupler is determined as a wavelength between the wavelengths in even mode and odd mode, and the two wavelengths are the length of the coupled line in the central tightly coupled portion.

FIG. 5 shows another embodiment of the present invention which operates in the same manner as the embodiment shown in FIG. 1, except that the output directions of the input/output terminals (2) and (2) are reversed. For this purpose, a through hole 8 is provided so that the joint patterns 5 and 6 intersect at the center.

Furthermore, FIG. 6 shows an embodiment in which the present invention is applied to a band-pass filter, in which the central loosely coupled portion CPL(L) has a microstrip circuit configuration, and the tightly coupled portions CPL(L) at both ends have a microstrip circuit configuration.
C) employs the coupled line section according to the present invention.
In the figure, 2a and 2b are substrates for coupled lines, 4a and 4b are input/output circuits, and 5a.

5b is a coupled line pattern, and 9.10 is a microstrip circuit pattern.

As described above, according to this embodiment, the substrate on which the coupling circuit pattern is formed on both sides is vertically mounted on the substrate on which the input/output circuit pattern is formed, and a space is provided between the two. With this configuration, there is no need to precisely control the gap between the coupling lines, and there is an effect that productivity is high and a product occupying a small area can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the close coupling part in a directional coupler etc. is constructed using a substrate different from that of the input/output circuit, so pattern accuracy is This has the effect of making it possible to easily realize a tightly coupled microwave integrated circuit, which would otherwise be virtually impossible to construct because it requires an extremely high value.

[Brief explanation of the drawing]

Fig. 1 is a perspective view and a side view of a microwave integrated circuit according to an embodiment of the present invention, Fig. 2 is a diagram for explaining the operation of an embodiment of the present invention, and Fig. 3 is a conventional directional coupling. The perspective view of the device, FIG. 4, FIG. 5, and FIG. 6 each show other embodiments of the present invention, and FIG. 4 shows an embodiment in which the present invention is applied to a three-section directional coupler. Figure 5 is the first
FIG. 6 is a diagram of an embodiment in which the input and output terminals shown in the figure are replaced, and FIG. 6 is a diagram of an embodiment in which the present invention is applied to a band pass filter. In the figure, 1 is an input/output line board (first group vi>
, 2.2a, 2b are coupled line boards (second board)
, 3 is a connection piece, 4 is an input/output circuit pattern, 5.5a,
5b and 6 are coupled line portion patterns, and 7 is a ground conductor.

Claims (1)

[Claims] (1) In a microwave integrated circuit having a close coupling function using a microstrip circuit using a dielectric substrate with a relatively high dielectric constant such as ceramic, the main body of the hybrid circuit has input/output lines configured on its upper surface. A second substrate having a predetermined thickness and having coupling line portions formed on both sides thereof, and a predetermined distance between the second substrate and the first substrate. The input/output of the coupled line section configured on both sides of the second substrate is arranged and fixed upright on the first substrate with a space or a low dielectric constant substrate sandwiched therebetween as a spacer. A microwave integrated circuit characterized in that a terminal is connected to an input/output line on the first substrate.