JPS63187806A - Plane type cross bar mixer - Google Patents

Abstract

PURPOSE:To decrease the leakage of a local oscillation signal to a conversion output terminal by mounting two mixer diodes to two locations where the local oscillation frequency signal on a coplaner line has inverted phase in a polarity in a way that both anodes or both cathodes are connected via the center conductor (cross bar) of the coplaner line. CONSTITUTION:The mount position of the two diodes 7 is changed to a position where the phase of the signal of the coplaner line 11 is inverted, one anode is connected to the other anode via a center conductor 12 of the coplaner line 11 and the opposite terminal of them is connected to a ground conductor of the coplaner line 11. The diodes 7 are mounted to a position where the phase of the signal is inverted and connected with each other in anti-parallel, that is, the anodes or the cathodes are opposed to each other resulting that the diodes are excited while the relation of the phase of signal and the polarity of the diode 4 is maintained and also a bias is applied from a bias circuit 8 to the diodes 7 via the center conductor 12 to attain the low conversion loss operation even under the low local oscillation power.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a planar crossbar mixer in the microwave band, and in particular, a diode bias type planar mixer suitable for low conversion loss operation under low local oscillation power. Regarding shaped crossbar mixers.

[Conventional technology]

Conventional planar cross per mixers are generally self-biased mixers in which the operating point is determined by a current excited by high local oscillation power. Regarding balance mixers using coplanar lines, for example,
It is described in Japanese Patent No. 1-61507.

However, in both cases, by adding an external DC bias, it is equivalent to inputting high oscillation power, and it is possible to operate with low conversion loss under low local oscillation power. Not mentioned.

[Problem that the invention seeks to solve]

The above conventional technology is based on the premise of low conversion loss operation under high local oscillation power, and consideration has been given to the technical difficulties involved in achieving high power output in high frequency bands, especially in the microwave band and above. There wasn't. In addition, in mixers used in communication transmitting and receiving equipment, local oscillation signals leak into the conversion output terminal and become spurious, so there are regulations in the Radio Law etc. against this, but the absolute amount of this local oscillation signal leakage is Since it is determined by the input power, there are problems such as an increase in spurious signals under high local oscillation power.

The purpose of the present invention is to provide a planar diode bias type that enables low conversion loss operation even when using a low power output circuit that is easy to implement in a local oscillator, and also reduces leakage of local oscillation signals to the conversion output terminal. We offer crossbar mixers.

[Means for solving problems]

The above purpose is to install two mixer diodes in two positions where the phases of local oscillation frequency signals on the coplanar line are inverted. This is achieved using a planar crossbar mixer in which both anodes or both cathodes are attached to polarities connected via the center conductor (crossbar) of the coplanar line, and a DC bias is applied to the mixer diode via the center conductor. Ru.

[Effect]

In the planar crossbar mixer described above, the two mixer diodes of the self-biased planar crossbar mixer are installed at the same position on the coplanar line, and one anode is connected via the center conductor of the coplanar line in direct current. The mixer diode is connected to the other cathode, and each opposite terminal is connected to the ground conductor of the coplanar line, and in this state, no external DC bias can be applied to the mixer diode.
Therefore, we changed the mounting positions of the two mixer diodes to two positions where the phases of the local oscillation frequency signals on the coplanar line are opposite to each other, and connected them in opposite directions, that is, in the direction where the anodes face each other or the cathodes face each other. By changing to The highly power-saving and economical configuration provides low conversion loss operation even at low local oscillation power.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is an exploded perspective view showing an embodiment of a planar crossbar mixer according to the present invention. Further, FIG. 2 is a sectional view of the central part of FIG. 1.

In FIGS. 1 and 2, 1 is a case conductor.

2 is a waveguide (RF terminal), 3 is a dielectric substrate, 4 is a ground conductor (pattern), 5 is an LPF (low pass filter), 6
is a BPF (band pass filter), 7 is a mixer diode, 8 is a bias circuit, 9 is an IF (intermediate frequency) terminal, 10
is the LO (local oscillation) terminal.

11 is a coplanar line (section), and 12 is a center conductor (crossbar).

Waveguide (RF terminal) of case conductor 1 in Figure 1 (Figure 2)
A coplanar line (portion) 11 disposed within 2 consists of a center conductor (crossbar) 12 formed on a dielectric substrate 3 and ground conductors (patterns) 4 on both sides. If two diodes 7 are installed at the same position on the coplanar line 11 as in the conventional self-bias method, one anode is connected to the other via the center conductor (crossbar) 12 of the coplanar line 11 in direct current. In a state where the terminals on the opposite side are connected to the ground conductor 4 of the coplanar line 11, no external DC bias can be applied. Therefore, according to the present invention, as shown in the figure, the mounting positions of the two diodes 7 are changed to positions where the phases of the signals on the coplanar line 11 are inverted, and one anode is connected to the other via the center conductor 12 of the coplanar line 11. It is connected to the anode, and each opposite terminal is connected to the ground conductor 4 of the coplanar line 11. In this way, if the diodes 7 are installed at the signal phase inversion positions and connected in opposite directions, that is, in the direction in which anodes and anodes or cathodes and cathodes face each other, the relationship between the phase of the signal and the direction of the diode 4 is maintained, and the excitation is maintained. At the same time, in this connected state, bias can be applied from the bias circuit 8 to the diode 7 via the center conductor 12, so that low conversion loss operation is possible even under low local oscillation power.

FIG. 3 is an explanatory diagram of the operation of FIG. 1 (FIG. 2).

In FIG. 3, the operation as an up converter is illustrated, 7a is an excitation signal, and 7b is a signal whose phase is π/2 compared to 7a.
The excitation signal excited at different times, 7C is the total excitation signal (total wave), 9a is the IP double signal, 9b is the IP" signal on the coplanar line (model) 11, and 9c is the LO double signal at the position where the phase is inverted. IF signal on the coplanar line 11, 10a is the LO multiplied signal 10b is the LO multiplied signal 1 on the coplanar line 11
0c is the LO multiplied signal on the coplanar line 11 whose phase is inverted. Note that the directions of the IF signal 9a and LO signal 10a in FIG. 3 include the IP terminal 9 and L'O terminal 10, LPF'5, and BPF6 in FIG. This is shown below.

Next, referring to FIG. 3, the operation of the mixer of FIG. 1 (FIG. 2) as an up-converter will be explained. First, from the LO (local oscillation) terminal 10 and the IP (intermediate frequency) terminal 9, each
LO signal 10a and IP signal 9a injected through PF 5 and BPF 6 are coplanar line section (model)
LO signal 10b whose phase is inverted and divided into two on 11
and IP signal 9b and arrive at diode 7, respectively. Then, at the IP frequency, the IP signal 9b and the IP signal 9c on the coplanar line 11 are almost in phase, and at the high frequency LO frequency, the LO signal 10b on the coplanar line 11 is in phase.
2 installed at a position where the phase is opposite to that of the LO signal 10o.
The diodes 7 excite signals in opposite directions with the excitation signals 7a and 7b, but since the conversion operation times of the two diodes 7 are shifted by half a cycle, the total This becomes an excitation signal (total wave) 7c. Therefore, this excitation signal 7c is TE. A converted wave (RF wave) is extracted into the waveguide 2 as a mode wave, and only the upper side band is extracted due to the wave number of the cutoff layer of the waveguide 2.

In addition, the two diodes 7 are connected to the center conductor 12 in terms of direct current.
Since the configuration is such that they are connected in parallel and in the same direction to the ground conductor 4, it is possible to apply a bias from the external bias circuit 8 through the center conductor 12. This allows for low conversion of the mixer under low local oscillation power. A loss operation is performed.

According to this embodiment, the structure is such that it is easy to apply external bias to the diode, enabling low conversion loss operation under low local oscillation power. Leakage can also be reduced.

〔Effect of the invention〕

According to the present invention, bias can be easily applied to the diodes of the planar crossbar mixer, thereby achieving low conversion loss operation under low local oscillation power and reducing leakage of local oscillation signals to the conversion terminals. This eliminates the need for a high local oscillation power circuit and requires a low-power circuit.It also simplifies or eliminates the need for filters to suppress leakage, improving economic efficiency, and allows input impedance adjustment and temperature compensation using bias current. This has the effect of improving performance.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective configuration diagram showing an embodiment of the planar crossbar mixer according to the present invention, FIG. 2 is a sectional view of the center of FIG. 1, and FIG. 3 is the operation of FIG. 1 (FIG. 2). It is an explanatory diagram. 4 -,, )P 2 q1 specification 2... Waveguide (R:F' terminal) 3... Dielectric substrate 4... Ground conductor (pattern) 5... LPF 6... BPF 7 ... Mixer diode 8 ... Bias circuit 9 ... IF terminal 10 ... LO terminal 11 ... Coplanar line (part) 12 ... Center conductor (crossbar).

Claims (1)

[Claims] 1. In a planar crossbar mixer having a coplanar line in which two mixer diodes are installed in the waveguide, the two mixer diodes are placed on the coplanar line at positions where the phases of the local oscillation frequency signals are inverted from each other. A planar crossbar mixer characterized in that both cathodes are attached to polarities connected to each other via a center conductor of a coplanar line, and a DC bias is applied to a mixer diode from a bias circuit via the center conductor.