JPS63116506A - Double balanced mixer - Google Patents

Abstract

PURPOSE:To sufficiently match the impedance of respective input terminals at a working frequency band, to minimize conversion loss and to be excellent in universal applicability by connecting a capacitor to an Lo port and an RF port. CONSTITUTION:On a hermetic sealing 102 having 8 pin terminals 101, a transmission transformer 103 and a bridge type diode 104 are arranged, and to an RF port, a capacitor 105 of 2.5pF is connected. Thus, the conversion loss can be made very small, a ferrite core and a winding are made into the same, only by changing the capacitor, the double balanced mixer to match to respective working frequency bands can be constituted and comes to be the mixer excellent in the universal applicability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to wireless devices using VHFHF microwaves, such as marine radios, personal radios, car phones, etc. 800M
Hz band) and intermediate frequency (for example, 45M for a car phone)
This relates to a double-balanced mixer, which is a mixer used for frequency conversion between Hz and Hz.

(Prior Art) Conventionally, a double-balanced mixer has a transmission transformer and a diode placed at a certain distance on a printed circuit board or on a hammetically sealed seal having bottle-shaped input and output terminals that can be inserted into the printed circuit board. It was arranged and configured in a flat manner. A perspective view of an example of this conventional double-balanced mixer is shown in FIG. In this conventional example, a transmission transformer 303 and a bridge type diode 304 are arranged on a seal 302 having eight pin terminals 301. Further, a circuit diagram of the double balanced mixer is shown in FIG.

In this conventional double-balanced mixer, in order to match the impedance of each input terminal in the frequency band used,
The shape of the ferrite core used in the transmission lance was changed, and the number of turns of the wire wound around the ferrite core was changed.

Then, an appropriate ferrite core and number of turns are selected depending on the frequency band used.

(Problems to be solved by the invention) As in the past, it is difficult to obtain sufficient matching by simply changing the shape of the ferrite core or changing the winding. Conversion loss could not be sufficiently reduced due to reflection at the Lo port.

Moreover, since the ferrite core and the number of turns differ depending on the frequency used, there is no versatility and the mass productivity is poor.

In view of the above, an object of the present invention is to provide a double-balanced mixer that has extremely low conversion loss and is versatile.

(Means for Solving the Problems) The present invention connects a capacitor to the LO port or the RF port in a double balanced mixer composed of two pairs of transmission transformers and four diodes using a ferrite core. be.

(Function) In the present invention, in order to match the impedance of each input terminal in the frequency band used, in addition to using the conventional means of changing the ferrite core or changing the number of turns, the present invention adds a capacitor. This made it possible to achieve more adequate matching.

(Example) FIG. 1 shows a perspective view of an example according to the present invention. In this embodiment, a transmission lance 103 and a bridge type diode 1.04 are arranged on a hametic seal having eight pin terminals 101, and a 2.5
A pF capacitor 105 is connected. The reflection characteristics of the RF port of this example are shown in graph a of FIG. Further, as a comparative example, the reflection characteristics of the RF port when the capacitor is removed from the example are shown in graph b in FIG.

As is clear from FIG. 3, the embodiment of the present invention has very good reflection characteristics.

In addition, the results of measuring the conversion loss characteristics of this example are shown in the first
- As shown in the table.

Table 1 = 3- Measurement conditions RF: 850MHz -3dBm Input Lo:
910MHz +7dBm input IF: 60M
Hz As is clear from Table 1, the examples of the present invention have extremely small exchange losses.

In the above embodiment, a double balanced mixer was described in which a capacitor was connected only to the RF port, but it is clear that the same effect can be obtained by connecting a capacitor only to the Lo port or to both the RF port and the LO port. be.

In addition, it is only necessary to change the capacitance of the capacitor according to the frequency band used, and by simply changing the capacitor while keeping the ferrite core and winding the same, it is possible to configure a double-balanced mixer that matches each frequency band used. is possible and has excellent versatility.

(Effects of the Invention) The present invention can sufficiently match the impedance of each input terminal in the frequency band used, and can extremely reduce the conversion loss of the double-balanced mixer. This is a double-balanced mixer with excellent performance and is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment according to the present invention, and FIG.
The figure is a circuit diagram of an embodiment according to the present invention, FIG. 3 is a graph of the reflection characteristics of the RF port of the embodiment of the present invention and a comparative example, and FIG. 4 is a perspective view of the conventional example. Figure 5.
The figure is a circuit diagram of a conventional example. 101...Pin terminal, 102...Hammetic seal, 103...Transmission transformer, 104...Bridge type diode, 1.05...Capacitor. Figure 1 Figure 2 Jun 30 shaku) Mi*defeated

Claims (1)

[Claims] A double balanced mixer comprising two pairs of transmission transformers using ferrite cores and four diodes, characterized in that a capacitor is connected to a Lo port or an RF port.