JPS63139401A - Microwave integrated circuit - Google Patents

Abstract

PURPOSE:To form a non-cyclic code converter by providing plural directionality couplers to couple to a ring-shaped microstrip line and a microstrip line and combining a signal to go around the ring-shaped microstrip line and a signal reflected by the directionality couplers. CONSTITUTION:To a ring-shaped microstrip line 1, two directionality couplers 2 and 3 are coupled with a reflecting coefficient at a connecting point as (r) and a transmission coefficient as (t). The ring-shaped microsstrip line 1 is composed of the square of a length L of one side and a directionality couplers 2 and 3 are respectively coupled to two sides facing the square. Thus, the transfer function (Z conversion) of an output at terminal B and C comes to be formulas I and II. Consequently, under the the conditions of r2=1/2, the denominator of the formulas I and II comes to be '1' and the transfer function comes to be non-cycle. Namely, the signal outputted from a circuit outputs the (pulse) of the special number even when the resistance for an amplitude loss is not provided, and converges. From the formulas I and II to the input of '1' from a terminal A, the output of the direction of (1, 1) is obtained from a terminal B, the output of the direction of (1, -1) is obtained from a terminal C and the code conversion is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A microwave integrated circuit using a ring-shaped microstrip line and a directional coupler and having an acyclic transfer coefficient is disclosed.

[Industrial application field]

The present invention relates to microwave integrated circuits, and more particularly to digital code conversion circuits formed by microwave integrated circuits.

Microwave integrated circuits have a strip line made of a conductor on the front surface of a high-permittivity substrate and a ground conductor on the back surface, and the electric field of high-frequency signals such as microwaves and millimeter waves is confined and propagated between the two conductors. Adopt the composition.

[Conventional technology]

It is known that a finite length microstrip line functions as a signal delay circuit. In addition, phenomena such as branching of microstrip lines, reflection of signals (pulses) due to connection with lines with different characteristic impedance, and coupling of signals by bringing lines close to each other are known4, and these phenomena can be combined. Various attempts have been made to manipulate and convert signals.

[Problem that the invention seeks to solve]

All of these conventionally proposed pulse conversion circuits are of the cyclic type. That is, the response pulse to one input pulse continues indefinitely, although the amplitude gradually decreases. Therefore, it is necessary to load a resistor in the circuit to provide signal loss, and the circuit operation is also complicated.

An object of the present invention is to provide a microwave integrated circuit constituting an acyclic code converter that does not require loading a resistor into the circuit.

[Means for solving the problems] FIG. 1 is a diagram showing the principle of the present invention. FIG. 1 shows a pattern of a microstrip line formed on a dielectric substrate of a microwave integrated circuit as a diagram.

Two directional couplers 2.3 are coupled to the ring-shaped microstrip line 1 with the reflection coefficient at the connection point being r and the transmission coefficient being t.

As a preferred embodiment of the present invention, in FIG. 1, the ring-shaped microstrip line l consists of a square with a side length L, and the directional couplers 2 and 3 are connected to two opposite sides of this square, respectively. The configuration to be combined is shown.

Here, by appropriately selecting the parameters described later, for one input pulse from terminal A, two pulses with positive amplitudes are sent from terminal B, and two pulses with positive and negative amplitudes are sent from terminal C. One pulse having each is outputted.

[Effect]

In the microwave integrated circuit of the present invention, an acyclic code converter is formed by skillfully combining a signal circulating on a ring-shaped microstrip line and a signal reflected by a directional positive coupler.

That is, as shown in Figure 2, from terminal B, there is a signal (■) that has passed through the connection point with the ring-shaped microstrip line, a signal (■) that has been repeatedly reflected on one side of the connection, and a signal (■) that has gone around the ring-shaped line. The signal ■ is combined and output.

On the other hand, as shown in Fig. 4, the signal ■ is output from terminal C by directional coupling via one side of the ring-shaped microstrip line, and is reflected at the terminal A-B side of the ring-shaped line and output. The reflected signal (2) and the signal (2) reflected at the terminal CD side and outputted are combined and output.

〔Example〕

(1) Theoretical Analysis Referring to FIG. 1, the operation of the microwave integrated circuit according to the present invention will be theoretically analyzed.

As shown in FIG. 1, if two directional positive couplers 2.3 are coupled to a square microstrip line 1 with a reflection coefficient at a connection point of t and a transmission coefficient of t, The transfer function (Z transformation) of the output at terminals B, , C is as shown in the following equation.

Therefore, under the condition that r''=1/2, the denominators of equations (1) and (2) become 1, and the transfer function becomes acyclic.

That is, the signal output from the circuit outputs a specific number of symbols (pulses) without providing any resistance for amplitude loss,
Converge.

From the above formula, for an input of "1" from terminal A, an output in the direction of (1, 1) from terminal B and (1, -1) from terminal C is obtained, and sign conversion is performed. That is understood.

Next, consider the frequency characteristics of the circuit.

The normalized output at terminals B and C is as follows.

1B(θ)1t-1-IC(θ)12...
・(4) However, here θquake ωL/l/ (v: velocity) ・・・・・・・・・
・(5) K= (Za/Z,)""...
...-(6)r= (K-1)(K+ 1)
・−・−−−−(7), 2. ．． 2. are the even and odd mode impedances of the directional coupler, respectively.

Under the above condition of r"=1/2, equation (3) is 1c(θ)bi=sin"θ (3).

becomes.

(2) Qualitative Analysis Referring to FIGS. 2 to 5, analyze the outputs from terminals B and C with respect to the input from terminal A. FIG. 2 is a diagram for explaining the output from terminal B, and FIG. 3 shows the main waveforms thereof.

A pulse of amplitude T input from terminal A is divided into two parts: one is coupled to the ring-shaped microstrip line, and the other is transmitted through the coupling point and output across the terminal. The output ■ transmitted through the connection point with the ring-shaped line can be calculated by appropriately selecting the transmission coefficient t at the connection point.
The amplitude T/ delayed by the time required to propagate the edge.
It is output as two pulses.

Further, the signal (2) reflected once on the terminal B side of the ring-shaped line and once on the terminal A side and output from the terminal B is output as a pulse with an amplitude T/4 with a delay of 3τ from the human input signal.

On the other hand, it connects to a ring-shaped line, goes around it, and connects to terminal B.
The signal ■ output from the input signal has an amplitude T delayed by 3 from the input signal.
/4 pulse.

Therefore, a pulse train that is a combination of these Φ to ■ is output from terminal B. This pulse train, as shown in FIG. 3, is two positive-directed pulses with an li1 period of 2τ and an amplitude of T/2.

Furthermore, it is clear from the above theoretical analysis that the signals in the above (■) that are further reflected and the signals in the above (■) that are further circulated around the ring-shaped line are canceled and are not output from the terminal B. Will.

FIG. 4 is a diagram for explaining the output from terminal B,
FIG. 5 shows the main waveform.

A part of the pulse of amplitude T inputted from terminal A is coupled to a ring-shaped microstrip line, coupled again to another directional coupler, and output as a signal ■. By appropriately selecting the coupling coefficient of the directional coupler, the pulse is output as a pulse with an amplitude T/2 delayed by the time τ required to propagate along one side of the ring-shaped line.

In addition, the signal ■ reflected once on the terminal B side of the ring-shaped line and output from the terminal C is delayed by 3τ from the input signal, and the signal
It is output as a 17/4 pulse.

On the other hand, the signal (2) coupled to the ring-shaped line, then reflected at the terminal side of the other directional coupler, and output from the terminal C becomes a pulse with an amplitude T/4 delayed by 3τ from the human input signal.

Since these signals (1) and (2) are output after being reflected an odd number of times, they are output as pulses whose amplitudes are in the opposite direction (negative direction) to the input pulse, as shown in the figure.

A pulse train that is a combination of these ① to ② is output from terminal C. This pulse train has a circumference M2 as shown in FIG.
There are two pulses in the positive and negative directions having an amplitude T/2 at τ.

Furthermore, it is clear from the above theoretical analysis that the signals in ■ above that are further reflected and the signals in ■ above that go around the ring-shaped line are canceled and are not output from terminal C. Will.

Furthermore, all input signals, reflected signals, and circulating signals cancel each other out from the terminal, and theoretically no signal is output.

(3) Specific device structure and its characteristics One example of a specific configuration of the present invention is shown in FIGS. 6(A) to 6(C).

FIG. 6(A) is a perspective view of the entire device, which is composed of a triplate type microwave integrated circuit. this is,
As shown in FIG. 6(B), a dielectric spacer β is sandwiched between two dielectric substrates α and T, each having a microstrip line formed on its surface, to form a sandwich structure.

FIG. 6(C) is a sectional view taken along line A-A' in FIG. 6(A).

Dielectric substrates each having a thickness h and each having a ground conductor formed on the back side are separated by a spacer having a thickness of 2S. The microstrip line on the surface of the dielectric substrate is formed of a conductor having a width W.

Now, the conditions for determining the dimensions of each part are the following two.
It is one.

■In order to make the transfer function acyclic, the value of the reflection coefficient r is
”=1/2.

■The characteristic impedance is set to Z-50Ω to ensure matching with the circuit connected to the input/output terminal. However, the reflection coefficient r has the above r= (K-1)(K+1) ・-・・-・-(7)
There is a relationship of z”=z, ・Zo ・・・・・・・・・(
Since the condition 8) is required, it is sufficient to find Z, , Zo that simultaneously satisfy the above equations (7) and (8). Zl and Zo are determined by the dimensions of each part (h:W:S) in FIG. 6 and the dielectric constant of the substrate.

Further, the length of one side of the ring-shaped microstrip line can be determined by the following formula, assuming that the pulse repetition frequency is f.

L=C/ (tr”” ・4 f) ・−= (9
) (where C: speed of light, tr: relative dielectric constant) The characteristics of the device actually created by the above calculation are shown in FIG.

Figure 7 shows the measurement results of the transfer frequency characteristics between each terminal, where (A) shows the measurement results between terminals A and B, and (B) shows the results between terminals A and B.
(C) shows the characteristics between terminals A and D.

The measurements were conducted under the following conditions.

Repetition frequency r -3(G)lz) Thickness of dielectric substrate h =, 1.6 (ta) Dielectric constant ε
r = 2.55 (Teflon glass) Width of microstrip line W - 0,24 (width) 1/ of spacer thickness
2, S = O, Q1 (tm) Length of one side of the ring-shaped line L = 16 (n) In Fig. 7, the dash-dotted line represents the theoretically calculated value when the repetition frequency is 3 GHz,
The two-dot chain lines each indicate theoretically calculated values when the repetition frequency is 2.5 GHz.

As is clear from the figure, the peak occurs at approximately 6 Gtlz between terminals A and B, and the peak occurs at approximately 3 GH2 between terminals A and C. That is, at terminal B, two positive pulses are output for one input pulse, so an output with a frequency twice that of the input signal is obtained. In addition, at terminal C, one pulse is applied in the positive and negative directions for one input pulse.
Since two pulses are output, an output with approximately the same frequency as the input signal can be obtained.

Incidentally, as is clear from the characteristics between terminals A and D in FIG. 7, the output from the terminal cannot exceed the error range.

(4) Other application examples In the embodiments shown in FIGS. 1 to 7 above, the coupling coefficient r and transmission coefficient t of the two directional couplers were the same, but
By appropriately differentiating them, it becomes possible to give a predetermined weight to the amplitude of the output pulse.

Further, by connecting a plurality of basic circuit configurations as shown in FIG. 1 in cascade, it is possible to form a circuit that outputs a pulse train consisting of a predetermined number of n pulses.

〔effect〕

As described above, according to the present invention, a gigabit/second high-speed pulse code converter can be formed using a very simple microwave integrated circuit. Further, the circuit of the present invention has the advantage that it does not require the use of any semiconductor elements or resistive elements, does not require a power supply, and has little variation in products.

Furthermore, the basic circuit of the present invention is expected to be used in such applications as forming an M-sequence encoder and using it for high-speed confidential digital transmission, generating partial response codes, and forming high-speed digital filters. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the basic principle of the present invention. FIG. 2 is a diagram for explaining the output from terminal B. FIG. 3 is a main part waveform diagram for explaining the output from terminal B. FIG. 4 is a diagram for explaining the output from terminal C. FIG. 5 is a main part waveform diagram for explaining the output from terminal C. FIG. 6 is a diagram for explaining one example of a specific configuration of the present invention. FIG. 7 is a diagram showing the measurement results of the transmission frequency characteristics between each terminal in the configuration of FIG. 6. In the figure, 1 is a ring-shaped microstrip line, 2.3
is a directional coupler. Z2ffi Please tell me the output from J issue f5.May 16r;
7 Figure 3 of the ladle
Ladle n gp gp 3 (2) 4 pieces 6”rC gau/1
The 8th ω*5 TLgIpJ ChiCka 1 that has 1 love day for the seven powers
Yame no Gakuiwa p sweat noodle shape ■(ε)@z
*A- of 12) (C) (A)
A' cross section

Claims (3)

[Claims] (1) A microwave integrated circuit comprising a ring-shaped microstrip line (1) and a plurality of directional couplers (2) and (3) coupled to the microstrip line (1). (2) The ring-shaped microstrip line (1) consists of a square with a side length L, and the directional coupler (2
), (3) are respectively coupled to two opposing sides of the square. (3) The characteristic impedance of the ring-shaped microstrip line (1) is Z, the directional coupler (2), (
The even and odd mode impedances of 3) are Z_a, respectively.
, Z_o, where r is the reflection coefficient of the directional coupler and the ring-shaped microstrip line, r^2 = 1/2, and K = (Z_a/Z_o)^1^/^2. r
=(K-1)(K+1), Z=Z_a・Z_o. The microwave integrated circuit according to claim 2.