JP2001068908A - Hybrid circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain miniaturization and reduction of the cost by projectingly providing a stab having an electric length, which is a specified multiple of the wavelength of a sprious signal as an object of insertion loss suppression, at all four input/output terminals. SOLUTION: A stab 2 having a width and a length, which cannot be ignored as distribution constants, is inserted to all the input/output terminals of a range coupler 1. The length of the stab is made into 1/4 of the wavelength (wavelength of the sprious signal) λS in any arbitrary high frequency band to be a suppression object so that an insertion loss suppression performance equal to conventional one added with a band rejection filter(BRF) can be provided. Namely, since the transmission phase of the range coupler is a multiple of λ/4 among all the input/output terminals, the required electric length between the stabs of the BRF is replaced by this length, the insertion loss of the unwanted frequency band specified by the length of the stab can be effectively suppressed, and the increase in the useless circuit area for filtering can be remarkably suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a microwave integrated circuit (MIC) and a microwave monolithic integrated circuit (MIC).
More particularly, the present invention relates to a hybrid circuit that suppresses insertion loss of a spurious signal (unnecessary frequency band) that becomes noise and requires a small area on the circuit.

[0002]

2. Description of the Related Art A directional coupler is an important passive functional circuit used for input distribution and synthesis in a distributed constant circuit in a microwave integrated circuit. Among them, a circuit having a coupling degree of 3 dB called a 90 ° hybrid circuit has a wide application field, and can reduce the occupied area on the circuit as compared with a 180 ° hybrid circuit using a rat race circuit, a slot line branch, or the like. Typical examples are range couplers and hybrid rings.

[0003] Since the range coupler and the hybrid ring have the same function, the range coupler will be described below as an example.
FIG. 7 shows a block diagram of the range coupler alone, FIG. 8 shows a pattern diagram of the range coupler alone, and FIG. 9 shows a characteristic diagram of the range coupler alone.

This range coupler has an input terminal PORT on a surface of a printed circuit board by a microstrip line.
1, output terminals PORT2 and PORT3, terminal POR
The pattern of T4 and one or more lines extending therefrom in parallel, respectively, are further connected to each other by an antenna. As shown, PORT1,2 and PORT3,4
Λ / 4 (λ is the wavelength of the high frequency at the operating frequency and is the wavelength of the signal input to the PORT 1), and the lines are distributedly coupled. Although not shown, a grounding copper foil is adhered to the entire back surface of the printed circuit board.

[0005] When the range coupler is constructed monolithically, the aerial is also constituted by a microstrip line. In this case, it becomes a multi-layer wiring, and is formed on another plane via another part and an insulating film, or is formed by an air bridge.

Due to such a configuration, the signal of the wavelength λ inputted to the PORT1 is distributed to the PORT3 and the PORT2. When the phases of the divided signals are represented by the wavelength λ, the PORT2 delays by λ / 4 with respect to the PORT1 and the PORT3 delays by λ / 2. The output level appears equally divided by PORT2 and PORT3.
It is not output to PORT4.

Here, as shown in the characteristic diagram of FIG.
In the insertion loss S31 from PORT1 to PORT3 shown in FIG. 8, the second and third operating frequencies (f0) are used.
Insertion loss in the harmonic frequency band (2 × f0, 3 × f0),
In the insertion loss S21 from the PORT1 to the PORT2 shown in FIG. 8, the insertion loss of the third harmonic frequency band (3 × f0) of the operating frequency (f0) is different from the operating frequency (f).
The loss is almost the same as the insertion loss in 0).

[0008] This causes unnecessary power passage in an unused band, which is an obstacle in radio wave management.
Some action is needed. For this reason, conventionally, a method of adding a band rejection filter (hereinafter abbreviated as BRF) to an output terminal of a hybrid circuit such as a range coupler has been adopted. In addition, other devices such as a band-pass filter (BPF) or a combination of a low-pass filter (LPF) and a high-pass filter (HPF) may be used. However, the use of the BRF can reduce the occupied area smaller than these. it can. In particular, there are many cases where a high-frequency amplifying element such as an FET or a HEMT exists in the preceding stage of the hybrid circuit, so that the second or third input is provided at the input.
It is common to include many harmonics. Therefore, B
The noise level is greatly improved by intensively suppressing the insertion loss in the frequency band of the second or third harmonic by RF.

An example of the insertion loss suppression of the second harmonic frequency band (2 × f0) using the BRF is shown in FIG. 10 as a block diagram, FIG. 11 as a pattern diagram, and FIG. 12 as a characteristic diagram. From the characteristic diagram of FIG. 12, S31 and S2
It can be confirmed that the insertion loss of No. 1 is suppressed.

[0010]

However, in the above configuration, the insertion loss of spurious signals such as harmonics can be suppressed, but as shown in FIG. 11, the area occupied by the BRF section for suppressing the insertion loss. However, it is larger than the area occupied by the main range coupler, making it impossible to reduce its size. Due to the large occupation area, cost reduction cannot be achieved. The problem arises.

[0011]

In order to solve the above-mentioned problems, the present invention provides a distributed constant type 90 having four input / output terminals.
The hybrid circuit is characterized in that it has stubs projecting from all of the four input / output terminals and having an electrical length of 波長 of the wavelength λ _S of the spurious signal to be subjected to insertion loss suppression.

The distributed constant 90 ° hybrid circuit having the four input / output terminals is suitable as a range coupler.

Alternatively, the distributed constant type 90 ° hybrid circuit having the four input / output terminals may be a hybrid ring.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. It is to be noted that the same reference numerals throughout the drawings denote the same or corresponding components.

An embodiment of the present invention for suppressing insertion loss in the second harmonic frequency band (2 × f0) is shown in FIG. 1 as a block diagram, FIG. 2 as a pattern diagram, and FIG. FIG. 3 shows a characteristic diagram of the device.

As shown in the block diagram of FIG. 1, a stub 2 having a width and a length that cannot be ignored in terms of a distribution constant is inserted into all input / output terminals of the range coupler 1. This is embodied in a pattern as shown in FIG. Specifically, a stub having a length of 1/2 of λ / 4 is provided at a transition from a wide 50 ohm line in PORT1 to PORT4 to a line that converges with a steep slope. That is, this transition is the circuit input end of the range coupler.

From the characteristic diagram shown in FIG. 3, the same level of insertion loss suppression in the second harmonic frequency band (2 × f0) as the suppression obtained by adding the conventional BRF (FIG. 12) can be obtained. You can see that.

Further, according to the present invention, the length of the stub is set to １ ／ of the wavelength (wavelength of the spurious signal) λ _{S in} an arbitrary harmonic frequency band to be suppressed, so that the BRF is reduced.
, The same insertion loss suppression performance as that of the conventional one can be obtained. That is, the length of the stub 2 in the aforementioned circuit is λ /
4, which is 1/2 times that of the stub 2. If the target of insertion loss suppression is the n-th harmonic frequency band, the electrical length of the stub 2 is 2. May be set to 1 / n times of λ / 4.

That is, the wavelength λ _{S of} the n-th harmonic frequency band
= Λ / n, for example, in the insertion loss suppression in the frequency band of the third harmonic, the frequency may be reduced to １ ／ instead of １ ／. FIG. 4 shows a pattern diagram of this example, and FIG. 5 shows a characteristic diagram thereof. As shown in FIG. 4, the length of the stub 2 is λ / 12. FIG. 5 also shows that the insertion loss in the third harmonic frequency band (3 × f0) is suppressed.

As described above, in the present invention, the stub 2 corresponding to the stub 4 used in the BRF in the conventional example shown in FIG. 11 is provided at all of the input / output terminals of the range coupler. That is, since the transmission phase of the range coupler is a multiple of λ / 4 between all input / output terminals,
Instead of the electrical length required between the stubs at F, the insertion loss in the unnecessary frequency band defined by the stub length is effectively suppressed, and the increase in unnecessary circuit area for filtering is greatly suppressed. be able to.

Although the embodiment has been described above, the present invention is not limited to this, and various modifications can be made without departing from the scope of the claims. For example, in the above embodiment, a microstrip line has been described as an example, but a coplanar line in which a ground pattern appears on the same plane as a circuit pattern can be similarly configured.

In the above embodiment, the range coupler has been exemplified, but instead, as shown in FIG.
Even when a hybrid ring having the same function as the range coupler is used, the same function as described above is performed.

Further, the signal for suppressing the insertion loss may be a signal of an arbitrary frequency as well as a harmonic as in the above embodiment. At this time, the wavelength λ of the arbitrary signal
_{For S} , the length of the stub is set to λ _S / 4.

[0024]

As described above, according to the present invention, a distributed constant type 90.degree. Hybrid circuit having the suppression performance of the harmonic frequency band can be obtained with substantially the same area as the occupied area of the circuit. Can be Thereby, size reduction can be achieved. Since the area of the BRF section is eliminated and the total occupied area is reduced, the cost can be reduced. Of course, the effect of improving the reliability and the safety factor due to the reduced pattern area and the reduced probability of occurrence of a failure such as a pattern cutoff can be obtained.

In particular, by using the present invention for a range coupler, the occupied area can be reduced over a relatively wide band.
When used for a hybrid ring, a simple pattern configuration can be used, which has the advantage that production costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a pattern diagram showing an embodiment of the present invention.

FIG. 3 is a characteristic diagram of the embodiment of FIG.

FIG. 4 is a pattern diagram showing another embodiment of the present invention.

FIG. 5 is a characteristic diagram of the embodiment of FIG.

FIG. 6 is a pattern diagram showing still another embodiment of the present invention.

FIG. 7 is a block diagram of a range coupler.

FIG. 8 is a pattern diagram embodying the range coupler of FIG. 7;

9 is a characteristic diagram of the range coupler shown in FIG.

FIG. 10 is a block diagram showing a conventional example in which a BRF is added to an output terminal of a range coupler.

FIG. 11 is a pattern diagram showing an embodiment of the range coupler with BRF of FIG. 10;

12 is a characteristic diagram of the range coupler with BRF shown in FIG.

[Explanation of symbols]

1: Hybrid circuit main body, 2, 4: Stub, 3: BR
F

Claims (3)

[Claims] 1. A distributed constant type 90 having four input / output terminals
In a hybrid circuit, there is provided a stub protruding from all of the four input / output terminals and having an electrical length of １ ／ of the wavelength λ _S of the spurious signal to be subjected to insertion loss suppression. . 2. The hybrid circuit according to claim 1, wherein the distributed constant 90 ° hybrid circuit having four input / output terminals is a range coupler. 3. The hybrid circuit according to claim 1, wherein the distributed constant type 90 ° hybrid circuit having four input / output terminals is a hybrid ring.