JPH09199886A - High-frequency device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the jamming of a beat in a high-frequency device for receiving a satellite broadcasting signal or the like. SOLUTION: In a frequency characteristic compensator 31 connected between a mixer 7 and a first intermediate-frequency amplifier 9, the mixer 7, a local oscillator 6, the compensator 31 excluding an air-core coil 32 used as an inductance, and the amplifier 9 are mounted on the surface 21a of a printed board 21. Hereby, as the coil 32 only of the frequency characteristic correction board 31 is mounted on the rear 21b of the board 21, the jamming of a beat can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency device for receiving satellite broadcast signals and the like.

[0002]

2. Description of the Related Art A conventional high frequency device will be described below.

A conventional high-frequency device is constructed as shown in the block diagram of FIG. That is, the input terminal 1
A high pass filter 2 connected to this input terminal 1,
The high-frequency amplifier 3 connected to the output of the high-pass filter 2, the AGC circuit 4 having the output of the high-frequency amplifier 3 connected to one input, the low-pass filter 5 connected to the output of the AGC circuit 4, A mixer 7 in which the output of the low-pass filter 5 is connected to one input and the output of the local oscillator 6 is connected to the other input,
Frequency characteristic corrector 8 connected to the output of the mixer 7
And a first intermediate frequency amplifier 9 connected to the output of the frequency characteristic corrector 8, and the first intermediate frequency amplifier 9
Surface acoustic wave filter (hereinafter SAW) connected to the output of
10) and this SAW filter 10
Of the second intermediate frequency amplifier 11 connected to the output of the FM and the FM connected to the output of the second intermediate frequency amplifier 11.
A detector 12 is provided, and one output of the FM detector 12 is connected to the other input of the AGC circuit 4 and an output terminal 13 is connected to the other output of the FM detector 12. . As shown in FIG. 7, the frequency characteristic corrector 8 includes an air-core coil 16 and a chip capacitor 17 connected in series between an input 14 and an output 15 of the input, an input 14, and a ground. A chip capacitor 18 connected between the air core coil 16, a chip capacitor 19 connected between the connection point of the air core coil 16 and the chip capacitor 17 and the ground, and a resistor connected in parallel with the air core coil 16. It was composed of 20 and. All the circuits including the frequency characteristic corrector 8 were mounted on the surface 21a of the printed board 21 as shown in FIG. In this way, the air-core coil 16 of the frequency characteristic corrector 8 is mounted on the surface 21 a of the printed board 21.

[0004]

However, in such a conventional configuration, the air-core coil 1 of the frequency characteristic corrector 8 is used.
Since 6 is also mounted on the same surface of the printed circuit board 21 together with other components, harmonics of the intermediate frequency (402.78 MHz) from the first intermediate frequency amplifier 9 are generated by the air-core coil 16 of the frequency characteristic corrector 8. The air core coil 16 of the frequency characteristic corrector 8 and the local oscillator 6 interfere with each other, and the oscillation frequency of the local oscillator 6 (1.4 to 1.9 GH is increased).
z) may enter the air-core coil 16 of the frequency characteristic corrector 8 and cause beat interference.

The present invention solves such a problem, and an object of the present invention is to provide a high frequency device for reducing beat interference.

[0006]

In order to achieve this object, a frequency characteristic corrector for a high-frequency device according to the present invention comprises an input terminal and a signal input to this input terminal supplied to one input and the other input. The mixer is supplied with the output of the local oscillator at the input of, the frequency characteristic corrector connected to the output of this mixer, the intermediate frequency amplifier connected to the output of this frequency characteristic corrector, and this intermediate frequency An output terminal to which the output of the amplifier is supplied is provided, and the frequency characteristic corrector has a series connection body of an inductance and a first capacitance provided between the input and the output, and between the input and the ground. A second capacitance connected to the mixer, a third capacitance connected between the inductance and the connection point of the first capacitance and ground, and the mixer, The local oscillator, the frequency characteristic corrector, and the intermediate frequency amplifier are mounted on the front surface of a printed circuit board, and only the inductance of the frequency characteristic corrector is mounted on the back surface of the printed circuit board. With this configuration, beat interference can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is such that an input terminal and a signal input to this input terminal are supplied to one input and the output of a local oscillator is supplied to the other input. A mixer to be supplied, a frequency characteristic corrector connected to the output of the mixer, an intermediate frequency amplifier connected to the output of the frequency characteristic corrector, and an output terminal to which the output of the intermediate frequency amplifier is supplied. The frequency characteristic corrector comprises: a serial connection body of an inductance and a first capacitance provided between an input and an output thereof; and a second capacitance connected between the input and a ground. A third capacitance connected between a connection point of the inductance and the first capacitance and ground, the mixer, the local oscillator, and the frequency characteristic corrector. A high-frequency device in which the intermediate frequency amplifier is mounted on the front surface of a printed circuit board and only the inductance of the frequency characteristic corrector is mounted on the back surface of the printed circuit board, and the inductance of the frequency characteristic corrector and other circuits are provided. Since they are separated by the printed circuit board, the harmonics of the output signal of the intermediate frequency amplifier circuit and the output of the local oscillator do not jump into the inductance and interfere with each other, so that beat interference can be reduced.

The invention according to claim 2 is the high-frequency device according to claim 1 in which the inductance is an air-core coil, and the air-core coil is used for the inductance.
The Q of the frequency characteristic corrector can be increased.

A third aspect of the present invention is the high frequency device according to the first aspect, wherein the inductance is a spiral pattern inductance formed on a printed circuit board.
Since the inductance is formed in a plane pattern, the high frequency device can be thinned and downsized.

A fourth aspect of the present invention is the high frequency device according to the first aspect, wherein a surface acoustic wave filter and a second intermediate frequency amplifier are connected between the intermediate frequency amplifier circuit and the output terminal. Since the surface acoustic wave filter having a good separation characteristic is used as the filter, the separation characteristic at the intermediate frequency is improved.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 2 shows an overall block diagram of the present invention. In FIG. 2, the high frequency device according to the present embodiment has an input terminal 1, a high-pass filter 2 connected to the input terminal 1, and a high-pass filter 2.
A high frequency amplifier 3 connected to the output of the high frequency amplifier 3, and an AGC circuit 4 connected to one input of the output of the high frequency amplifier 3.
The low-pass filter 5 connected to the output of the AGC circuit 4, the mixer 7 having the output of the low-pass filter 5 connected to one input and the output of the local oscillator 6 connected to the other input, A frequency characteristic corrector 31 connected to the output of the mixer 7, a first intermediate frequency amplifier 9 connected to the output of the frequency characteristic corrector 31,
SA connected to the output of the first intermediate frequency amplifier 9
The W filter 10, a second intermediate frequency amplifier 11 connected to the output of the SAW filter 10, and the second intermediate frequency amplifier 11.
The FM detector 12 to which the output of the intermediate frequency amplifier 11 is connected, and one output of the FM detector 12 is the AGC.
The output terminal 13 is connected to the other input of the circuit 4 and is connected to the other output of the FM detector 12.

FIG. 3 shows the frequency characteristic corrector 3 of the present invention.
1 shows a circuit diagram of 1. In FIG. 3, the frequency characteristic corrector 31 includes an air-core coil (used as an example of an inductance) 3 provided between an input 14 and an output 15 of the frequency characteristic corrector 31.
2 and a chip capacitor (used as an example of capacitance) 17 in series, a chip capacitor 18 connected between the input 14 and ground, a connection point between the air core coil 32 and the chip capacitor 17. It is composed of a chip capacitor 19 connected between the ground and a resistor 20 connected in parallel with the air core coil 32.

The operation of the high frequency device configured as described above will be described below. The satellite broadcast signal (1 GHz to 1.4 GHz) input to the input terminal 1 is input to the high-pass filter 2, the signal of 1 GHz or less is suppressed, and the high-frequency amplifier 3 amplifies the signal output from the high-pass filter 2. , The signal level of the AGC circuit 4 is controlled by the FM detector 12 according to the strength of the input signal,
Signals above GHz are suppressed. This signal is a signal desired by the mixer 7 and the local oscillator 6 at an intermediate frequency (402.7).
8 MHz), the frequency characteristic corrector 31 corrects the frequency characteristic of the intermediate frequency band, and the first intermediate frequency amplifier 9 amplifies the intermediate frequency. Further SAW
The filter 10 suppresses unnecessary signals other than the intermediate frequency, and the second intermediate frequency amplifier 11 amplifies the intermediate frequency. The signal is FM-detected by the FM detector 12, and a video signal is output to the output terminal 13.

FIG. 1 shows a sectional view of the main part of the frequency characteristic corrector. In FIG. 1, the surface 21 of the printed circuit board 21
The mixer 7, the local oscillator 6, the first intermediate frequency amplifier 9, and the frequency characteristic corrector 31 excluding the air core coil 32 are mounted on a. Then, the frequency characteristic corrector 31
Only the air core coil 32 is mounted on the back surface 21b of the printed board 21. As a result, the intermediate frequency (402.78M) from the first intermediate frequency amplifier 9 to the air-core coil 32 is transmitted.
(Hz) and the interference between the local oscillator 6 and the air-core coil 32 are reduced.

FIG. 4 is a sectional view showing the main part of a frequency characteristic corrector according to another example. In this way, the frequency characteristic corrector 3
By setting the inductance of No. 1 to the pattern inductance 33, the volume is reduced, and the high-frequency device can be thinned and miniaturized.

FIG. 5 is a plan view of the pattern inductance. By making the pattern inductance 33 spiral 34 as shown in FIG. 5, the space of the printed circuit board 21 can be used efficiently, and high-density mounting is possible.

[0017]

As described above, according to the present invention, the mixer, the local oscillator, the frequency characteristic corrector and the intermediate frequency amplifier are mounted on the surface of the printed circuit board, and only the inductance of the frequency characteristic corrector is provided. Is mounted on the back surface of the printed circuit board, the printed circuit board can separate the inductance of the frequency characteristic corrector from other circuits, so that a high frequency device with reduced beat interference can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a high-frequency device according to an embodiment of the present invention.

FIG. 2 is a block diagram of the entire high frequency device.

FIG. 3 is a circuit diagram of a main part of the high frequency device.

FIG. 4 is a sectional view of a main part of another example of the high-frequency device.

FIG. 5 is a plan view of the inductance of the high frequency device.

FIG. 6 is an overall block diagram of a conventional high frequency device.

FIG. 7 is a circuit diagram of a main part of the high frequency device.

FIG. 8 is a sectional view of the main part of the same high-frequency device.

[Explanation of symbols]

 1 Input Terminal 6 Local Oscillator 7 Mixer 8 Intermediate Frequency Amplifier 13 Output Terminal 17 Chip Capacitor 18 Chip Capacitor 19 Chip Capacitor 21 Printed Circuit Board 31 Frequency Characteristic Corrector 32 Air Core Coil

Claims (4)

[Claims] 1. An input terminal, a mixer to which a signal input to the input terminal is supplied to one input and an output of a local oscillator is supplied to the other input, and the mixer is connected to the output of the mixer. A frequency characteristic corrector, an intermediate frequency amplifier connected to the output of the frequency characteristic corrector, and an output terminal to which the output of the intermediate frequency amplifier is supplied,
The frequency characteristic corrector includes a series connection body of an inductance and a first capacitance provided between an input and an output thereof, a second capacitance connected between the input and a ground, and the inductance. A third capacitance connected between the connection point of the first capacitance and ground, and printing the mixer, the local oscillator, the frequency characteristic corrector, and the intermediate frequency amplifier. A high frequency device which is mounted on the front surface of a board and only the inductance of the frequency characteristic corrector is mounted on the back surface of the printed board. 2. The high frequency device according to claim 1, wherein the inductance is an air-core coil. 3. The high frequency device according to claim 1, wherein the inductance is a spiral pattern inductance formed on a printed circuit board. 4. The high frequency device according to claim 1, wherein a surface acoustic wave filter and a second intermediate frequency amplifier are connected between the intermediate frequency amplifier circuit and the output terminal.