JPH01282910A - Frequency conversion circuit - Google Patents

Abstract

PURPOSE:To make an inexpensive dielectric base material usable by providing a BPF made of a microstrip line between an RF signal input terminal and other terminal of a mixer diode whose one terminal is connected to ground. CONSTITUTION:An input signal from the RF signal input terminal 1 is given to a BPF 9 and only an RF signal is given to a mixer diode 3. A local signal and an IF signal through a BPF 10 are given to the mixer diode 3 from a local signal input terminal 4. Then the IF signal subjected to frequency conversion is outputted to an IF signal output terminal 7 through an LPF 11. Then the BPF 9 made of microstrip lines 90-96 is so constituted that a gap like a lambda/2 coupling type BPF is not in existence with respect to the transmission line. Thus, a material of a dielectric base forming the BPF is constituted by an inexpensive material at a microwave band such as a glass epoxy resin thereby reducing the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a frequency conversion circuit for satellite broadcast receiving equipment.

(Conventional technology) An example of a conventional frequency conversion circuit is shown in FIG.

This is an RF multiplied signal from an RF signal input terminal 1 disposed on a dielectric substrate, a λ/2 table type trapezoidal bandpass filter 2, and an RF multiplied signal mixed into a mixer diode 3.

This mixer diode is a single end-rad type mixer whose anode side is grounded, and it receives RF multiplied signals and other signals.
A local signal is inputted from the local signal input terminal 4 via the λ72 coupled band-pass filter 5, and both the local signal and the IF multiplied signal are inputted to this mixer diode and frequency-converted.

Then, only the IF multiplied signal frequency-converted by the mixer diode is outputted to the IF signal output terminal 7 via the low-pass filter 6.

In this case, since a λ/2 trapezoidal band-pass filter is used, one circuit is open in terms of direct current. Therefore, the choke pattern 8 for the DC return path is set to a pattern length and width that is open to the IF multiplied signal.

(Problems to be Solved by the Invention) As mentioned above, in conventional frequency conversion circuits, a λ/2 trapezoidal trapezoidal band-pass filter is used to separate the RF multiplied signal and the local signal. It was necessary to use materials with good performance and high cost, such as Teflon material.

Furthermore, as described above, since the λ/2 coupling type bandpass filter is used, a choke pattern for the DC return path is required, which has the disadvantage of restricting the design of one circuit and increasing complexity and cost.

It is an object of the present invention to solve the above-mentioned conventional problems, to enable the use of low-cost dielectric substrate materials, and to create a frequency conversion circuit that does not require a choke pattern for a DC return path.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a bandpass filter consisting of a microstrip line inserted between an RF signal input terminal and the other end of a mixer diode whose one end is grounded. A circuit is connected to the dielectric substrate, in which a local signal is input through a filter to the connection between the other end of the mixer diode and the bandpass filter, and an IF multiplied signal is extracted from the connection through the filter. The present invention is characterized by the above configuration.

(Function) The present invention has the above-described configuration, so that the R
For the bandpass filter on the F signal input terminal side, without using a λ/2 coupled bandpass filter, a microstrip line in series with the transmission line and a microstrip line in parallel with the ground can be used to control any wavelength. By combining a microstrip line with a characteristic impedance, it is possible to provide the same performance as the λ/2 coupled bandpass filter. Further, since electric field coupling is not performed as in a λ/2 coupling type bandpass filter, the dielectric substrate material has a property that it is not susceptible to high frequency characteristics.

Furthermore, since the bandpass filter composed of microstrip lines is grounded in terms of DC, a choke pattern for the DC return path is unnecessary and simplified.

For this reason, the present invention can provide a frequency conversion circuit that uses an inexpensive dielectric substrate material and has a simple circuit.

(Embodiment) FIG. 1 shows a conceptual diagram of a pattern of an embodiment of the present invention, in which RF signal input terminals 1. Mixer diode 3.
The local signal input terminal 4 and the IF signal output terminal 7 are the same as those shown in FIG.

In place of the λ/2 coupled band-pass filter shown in FIG. Microstrip line 90-93
The bandpass filter 9 is configured by connecting microstrip lines 94 to 96 in parallel between the midpoint of these microstrip line connections and the ground, and optimizing the characteristic impedance and width of each microstrip line. do.

Further, 10 is a band pass filter that passes a local signal, and 11 is a low pass filter that passes an IF multiplied signal.

The conceptual diagram of FIG. 1 above is shown in a more actual circuit pattern as shown in FIG. 2. Here, the dash in each number corresponds to the corresponding number in FIG.

The operation of this embodiment is similar to the operation described in FIG.
The RF multiplied signal is input to the mixer diode 3. The mixer diode receives both the local signal passed through the band pass filter 10 and the IF multiplied signal from the local signal input terminal 4, and the frequency-converted IF multiplied signal passes through the low pass filter 11.
The signal is output to the F signal output terminal 7.

The bandpass filter 9 consisting of the microstrip lines 90 to 96 of the present invention has a conventional λ/2
There is no gap like in a combined bandpass filter,
The material of the dielectric substrate that makes up the bandpass filter is
In the microwave band (3 to 5 GHz), inexpensive materials such as glass epoxy resin can be used, and the construction cost can be reduced.

In addition, in the conventional λ/2 type bandpass filter, it is difficult to freely change the pattern shape, but in the present invention, the bandpass filter made of microstrip lines has a pattern in which all the structures are connected. Therefore, the shape can be changed freely, increasing the degree of freedom in design.

Furthermore, since the bandpass filter is DC-grounded, there is no need to provide a choke pattern for a conventional DC return path, and there are advantages such as no change in characteristics caused by the choke pattern.

In the above-mentioned embodiment, the example of the RF multiplied signal bandpass filter 9 has a three-stage configuration, but even if the configuration is changed to 2 to 5 stages, etc., to achieve the optimum filter characteristics, the same result as described above can be obtained. It is effective.

Furthermore, although glass epoxy resin is shown as an example of the substrate material, the present invention is not limited to this, and the same effect as described above can be obtained even if materials such as ceramic materials and polyester materials are used.

(Effects of the Invention) As described above, according to the present invention, a bandpass filter composed of a microstrip line connected in series to an RF double signal bandpass filter transmission line and a microstrip line connected in parallel to the ground is used to Cheap body substrate materials can be used. In addition, since the bandpass filter is grounded in terms of DC, there is no need to create a choke pattern for the DC return path, and the filter has a transmission line configuration using microstrip lines, allowing for greater freedom in pattern layout, etc. It has a large effect.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a pattern of a frequency conversion circuit which is an embodiment of the present invention, Fig. 2 is an actual pattern configuration diagram of a frequency conversion circuit which is an embodiment of the invention, and Fig. 3 is a conventional frequency conversion circuit. It is a pattern block diagram of a circuit. 1...RF signal input terminal, 2, 5...λ/2
Combined band pass filter, 3... mixer diode, 4... local signal input terminal, 6.1
1...Low pass filter. 7... IF signal output terminal, 8... Choke pattern, 9, 10... Band pass filter, 12...
・Connection part, 90-96...Microstrip line. Patent Applicant: Matsushita Electric Industrial Co., Ltd. Figure 1 90-96 MicroStocks 7' Line

Claims (1)

[Claims] A bandpass filter made of a microstrip line inserted between the RF signal input terminal and the other end of a mixer diode whose one end is grounded is connected, and the connection part between the other end of the mixer diode and the bandpass filter is connected. 1. A frequency conversion circuit comprising a circuit connected to input a local signal through a filter and to output an IF signal from the connection portion through the filter on a dielectric substrate.