JP2980033B2 - Harmonic mixer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic mixer (even harmonic mixer) used for a radio communication device in a microwave band or a millimeter wave band, and more particularly, to a frequency characteristic having good conversion loss of a mixer and a local oscillator. The present invention relates to a harmonic mixer having good isolation characteristics between a signal introduction unit and an RF signal output unit.

[0002]

2. Description of the Related Art The configuration of a conventional harmonic mixer will be described with reference to the drawings.

FIG. 2 is a diagram showing a configuration of a conventional harmonic mixer using a two-layer printed wiring board. 2A and 2B show a top view of a conventional harmonic mixer and a cross-sectional view taken along line AA, respectively.

In FIG. 2A, reference numeral 3 denotes a microstrip line formed on one surface of a two-layer printed wiring board 21, and a local signal input connector (SMA type coaxial connector) 9
Local signal introduction unit for introducing a local signal input from the mixer into a mixer diode (anti-parallel diode) 15;
Is formed by a microstrip line in the same manner as 3 and an RF signal output section for outputting the output of the anti-parallel diode 15 to the RF signal output connector 10 (SMA type coaxial connector). , A short stub connected to the second layer surface by a via hole, 6 an open stub with an open end, 11 an anti-parallel diode 15 for an IF signal input from an IF signal input connector 12 (SMA type coaxial connector).
Reference numeral 15 denotes an anti-parallel diode in which two mixer diodes are connected in opposite directions.

As shown in FIG. 2B, the two-layer solid earth surface of the two-layer printed wiring board 21 is connected to the connector conductors of the local signal input connector 9 and the RF signal output connector 10 described above. , The ground is common.
Further, although not shown, it is also connected to the conductor of the IF signal input connector 12.

As shown in FIG. 2, the short stub 5 and the open stub 6 are provided in the same direction with respect to the signal line. Therefore, there is an advantage that the overall size of the mixer can be reduced, but the two stubs are easily coupled electromagnetically, and the frequency characteristics of the conversion loss of the harmonic mixer and the leakage characteristics of the local signal to the RF port are likely to deteriorate.

On the other hand, as another configuration, there is a harmonic mixer shown in FIG. Here, FIGS. 3 (a) and 3 (b)
FIG. 1 shows a top view and a cross-sectional view of a conventional harmonic mixer, respectively.

This figure is almost the same as the structure shown in FIG. 2 except that a short stub 5 and an open stub 6 are provided on both sides of a signal line.

The harmonic in which the two stubs shown in FIG. 3 are provided on both sides of the signal line is superior to the harmonic mixer shown in FIG. 2 in terms of coupling between the two stubs, but the coupling is not perfect, and Figure 2 shows the area occupied by the mixer
Will be slightly less than twice.

As another conventional example of the harmonic mixer, there is Japanese Utility Model Laid-Open No. 02-206903 (not shown). This harmonic mixer has an effect of suppressing transmission loss of an RF signal and reducing conversion loss by using a waveguide and a coplanar line, but does not mention the coupling between the two stubs. .

[0011]

As shown in FIG. 2, in the prior art, the stubs at both ends of the anti-parallel diode are mounted such that their tips are directed in the same direction, and both are substantially orthogonal to the signal line direction. And arranged in parallel with each other.

The stubs opposed in the same direction are electromagnetically coupled to each other, causing a conversion characteristic of the mixer to have a frequency characteristic. In addition, such coupling has a problem that the localization signal leaks to the RF signal output unit, thereby deteriorating the isolation characteristics.

Further, in the prior art shown in FIG. 3, in order to solve the above-mentioned problem of electromagnetic coupling, the ends of both stubs are arranged in opposite directions.

However, in the configuration shown in FIG. 3, the open / short stubs having a length of 1/4 of the effective wavelength of the local signal on the printed wiring board extend in opposite directions to the signal line direction. There is a problem that the area occupied by the mixer on the plate is increased.

The present invention solves the problem of the conventional harmonic mixer by disposing both open and short stubs of the harmonic mixer on the front and back surfaces of a printed wiring board separated by a solid earth surface. It is an object of the present invention to minimize electromagnetic coupling between stubs and to optimize mixer characteristics, particularly frequency characteristics of conversion loss, and leakage of Lo signals to an RF signal port.

Further, by disposing both stubs on the front and back surfaces,
An object of the present invention is to enable signal lines to be arranged in the same direction, and to minimize the area of a printed wiring board occupied by a mixer.

[0017]

According to the present invention, there is provided a harmonic mixer mounted on an n-layer (n is a natural number of 3 or more) printed wiring board. A short stub having one end connected to the tip of the first microstrip line and the other end grounded;
And a second microstrip line for introducing an RF signal and an open stub connected to the tip of the second microstrip line are provided on the n-th layer surface. And the other end of the anti-parallel diode is connected to the second microstrip line with all the second to (n-1) th layers being solid ground planes.

[0018] The short stub and the open stub are attached so that their respective tips face the same direction.

Further, the harmonic mixer of the present invention uses a three-layer printed wiring board having a second layer as a solid ground plane as a printed wiring board constituting a circuit. Local signal (Lo
The microstrip line of the introduction part, the anti-parallel diode, and the input short stub are arranged in the first layer. The microstrip line of the RF signal output section and the open stub of the diode output are arranged in the third layer. The microstrip lines of the diode output section and the third-layer RF signal output section are connected by via holes penetrating the first to third layers.

According to this configuration, the Lo signal introduction portion, the first layer serving as the short stub surface and the RF signal output portion, and the three layers serving as the open stub surface are completely electromagnetically shielded by the second solid ground. Thus, the coupling between the two can be theoretically minimized.

Since the second layer of the three-layer printed wiring board is a solid ground, the Lo signal introduction portion and the short stub formed on the first layer are completely connected to the RF signal output portion of the third layer and the open stub. Is electromagnetically shielded.

[0022]

Embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1A and 1B are a top view and a sectional view, respectively, showing the configuration of a harmonic mixer according to the present invention.
The same components as those described with reference to FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

Here, FIG. 1 is most different from FIGS. 2 and 3 in that a three-layer printed wiring board 1 is used instead of the two-layer printed wiring board 1.
The microstrip line 3 of the local signal introducing portion is provided on the first layer of the three-layer printed wiring board 1 having the second layer as a solid earth surface.
In addition, a short stub 5 connected to the diode input terminal and an anti-parallel diode 15 are arranged. Further, a microstrip line 4 for RF signal output and an open stub 6 connected to the diode output terminal are arranged on the third layer by via holes 8 penetrating from the output terminal of the diode 15 to the first to third layers. I have.

Next, the operation of the embodiment of the present invention will be described.

The local oscillation signal fed from the local oscillation signal introducing section 3 to the anti-parallel diode 15 is
, But is reflected by the open stub 6 provided at the diode output terminal 15 and the diode 15
The power is used effectively to switch the power.
On the other hand, the RF output signal generated by the diode 15 is reflected by the short stub 5 at the input of the diode 15 and the power is effectively transmitted to the RF signal output 4.

Here, the local oscillation signal frequency × 2 ≒ the RF signal frequency, that is, the intermediate frequency (IF) << the local oscillation signal frequency,
Therefore, the open stub 6 described above has a short surface at the base of the stub for the local signal, and the short stub has a short surface at the base for the RF signal, and thus has the above-described reflection characteristics.

The two stubs are respectively a local signal, RF
It plays the role of reflecting the signal at each end face,
Each exists independently. That is, it is a necessary condition that coupling is not electromagnetically performed.

Thus, by using the arrangement according to the invention, both stubs can be completely independent.

FIG. 1 will be described in more detail.

A microstrip line 16 for introducing a local oscillation signal and a microstrip line 4 for outputting an RF signal are provided on the first and third layers of the three-layer printed wiring board 1 serving as the second-layer solid ground plane.

An anti-parallel diode 15 in which two diodes having the same diode characteristics are connected so as to be opposite to each other in polarity is connected to the end face of the microstrip line 3 for introducing a local signal from the first layer. The pole is connected to the RF signal output microstrip line 4 by a via hole 8 penetrating from the first layer to the third layer.

If the frequency of the local oscillation signal is fLO and the frequency of the IF signal is fIF << fLO, the frequency of the RF signal extracted from the harmonic mixer is fRF. In this case, fRF = 2 × fLO ± fIF ≒ 2 × f
It becomes LO.

Next, fLO, fRF on the printed wiring board in consideration of the wavelength shortening rate due to the used printed wiring board.
Are defined as λg (LO) and λg (RF), respectively.

The lengths of the short stubs and open stubs 5 and 6 disposed on the local signal and the RF signal side of the anti-parallel diode 15 are set to を λg (LO) (= １ ／).
λg (RF)), the root of the short stub becomes a short surface for the RF signal, and is reflected to the RF signal output port side. Further, the root of the open stub is a short surface for the local oscillation signal, and is reflected to the local oscillation signal input port, that is, the diode side. Thereby, the power of the local oscillation signal for switching the diode is supplied to the diode without waste, and further, fRF = 2 × fLO ± fIF generated by the anti-parallel diode
The resulting RF signal is output to the RF output port without waste.

In the present invention, the above-mentioned two stubs are formed by using a three-layer printed wiring board, and the ground planes of the first and third microstrip lines are made common to the inner second layer. They are arranged on the first layer and the third layer to suppress the occurrence of electromagnetic coupling.

Of course, since the printed wiring board is ultimately housed in a metal case in which the side surfaces are in close contact, deterioration of the shield between the first layer and the third layer due to leakage from the side direction or the like can be prevented.

The harmonic mixer shown in the above description has been shown and described as a transmission frequency converter for converting the frequency of an IF signal input to obtain an RF signal output.

However, the present invention is not limited to this.
Needless to say, the receiving frequency converter can be configured to exchange the F signal and the IF signal, input the RF signal, and obtain the IF signal output.

In the embodiment of the present invention, a harmonic mixer using a three-layer substrate has been described. However, the present invention can be applied to a multilayer substrate having three or more layers. That is, for an n-layer (n is a natural number of 3 or more) layer substrate, the first
On the layer surface, a microstrip line 3 for local oscillation introduction, an anti-parallel diode 15, and a short stub 5 are provided. Further, a microstrip line 4 for outputting an RF signal and an open stub 6 are provided on the n-th layer surface. The second to (n-1) layers are all solid ground surfaces,
One end of the anti-parallel diode 15 may be connected to the microstrip line 4 by a via hole penetrating from the first layer to the n-th layer.

[0041]

As described above, in the harmonic mixer of the present invention, two stubs are arranged separately on the first and third layers of a three-layer printed wiring board, and the second layer is formed on the first and third layers. As a common ground plane, and the electromagnetic shielding between them is completely completed theoretically. Therefore, the mixer characteristics (the conversion loss f,
There is no deterioration of leakage of the local oscillation signal to the RF port).

Further, since there is no coupling between the two stubs, they can be arranged on the same side with respect to the signal line, the area of the harmonic mixer occupying the printed wiring board can be minimized, and the size and weight can be reduced.

[Brief description of the drawings]

FIG. 1A is a top view of a harmonic mixer showing an embodiment of the present invention. (B) It is AA sectional drawing of the harmonic mixer which shows embodiment of this invention.

FIG. 2A is a top view of a conventional harmonic mixer. (B) It is AA sectional drawing of the conventional harmonic mixer.

FIG. 3A is a top view of another conventional harmonic mixer. (B) It is AA sectional drawing of another conventional harmonic mixer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 3 layer printed wiring board 2 2 layer solid earth surface 3 Local signal introduction part 4 RF signal output part 5 Short stub 6 Open stub 7 Via hole which connects 1-2 layers 8 Via hole which connects 1-3 layers 9 Local signal input connector REFERENCE SIGNS LIST 10 RF signal output connector 11 IF signal introduction unit 12 IF signal input connector 13 Via hole connecting 2 to 3 layers 14 Via hole connecting 2 to 1 layer 15 Anti-parallel diode 16 Connecting ground plane of connector and solid ground plane of printed circuit board 2 layer Via hole 21 2-layer printed wiring board

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03D 7/00-7/02 H01P 5/02 603 E

Claims (6)

(57) [Claims] 1. A harmonic mixer mounted on an n-layer (n is a natural number of 3 or more) printed wiring board, wherein: a first microstrip line for introducing a local oscillation signal; A short stub with one end connected to the end of the stripline and the other end grounded,
An anti-parallel diode connected to the tip of the first microstrip line; a second microstrip line for introducing an RF signal on the n-th layer surface; and an open stub connected to the tip of the second microstrip line. Wherein the second end of the anti-parallel diode and the second microstrip line are connected to each other, with the second to (n-1) th layers being all solid ground planes. 2. The harmonic mixer according to claim 1, wherein the short stub and the open stub are attached such that respective tips face in the same direction. 3. The harmonic mixer according to claim 1, wherein each of the short stub and the open stub has a length substantially equal to １ ／ of an effective wavelength of the local oscillation signal. 4. The harmonic mixer according to claim 1, wherein an IF signal path is provided on the n-th layer surface and connected to the second microstrip line. 5. The harmonic mixer according to claim 1, wherein the anti-parallel diode connects two diodes having uniform characteristics so as to face each other with opposite polarities. 6. The connection between the other end of the anti-parallel diode and the second microstrip line,
2. The harmonic mixer according to claim 1, wherein a via hole connecting the first layer to the n-th layer is used.