JP3343032B2 - High frequency amplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency amplifier, and more particularly to a high-frequency amplifier having a filter.

[0002]

2. Description of the Related Art A high frequency amplifier provided with a filter amplifies a first intermediate frequency signal of, for example, a 1 GHz band from a converter attached to a satellite broadcast receiving antenna, for example.
It may be used for an amplifier input to a tuner. In such a high-frequency amplifier, a high-pass filter that allows the first intermediate frequency signal to pass is used as a filter. Such a high-pass filter has been constituted by an air-core coil and a capacitor.

[0003]

However, in order to adjust the inductance of the air-core coil to a desired value, it is necessary to adjust the number of turns or the pitch. The high-frequency amplifier described above has a problem that the time required for the adjustment is long. In addition, since the adjustment cannot be automated, the operator must perform the adjustment one by one, which causes an increase in the cost of the high-frequency amplifier.

[0004]

According to a first aspect of the present invention, there is provided a high frequency amplifying means formed on a printed circuit board and at least an input side and an output side of the high frequency amplifying means. One has a cascade-connected high-pass filter. This high-pass filter may be cascaded to both the input side and the output side of the high-frequency amplifier. This high-pass filter is configured on a printed circuit board. A low-pass filter is connected in parallel with the high-frequency amplifier and the high-pass filter. This low-pass filter is also formed on the printed circuit board.
The high-pass filter and the low-pass filter have a printed pattern coil provided on the printed circuit board. As the print pattern coil, for example, a spiral type or a zigzag type can be used. The printed circuit board is a double-sided printed circuit board, the low-pass filter has a printed pattern coils of the plurality of zigzag type formed on one surface of the printed circuit board, the printed pattern co these zigzag
A pre-defined inductance that is formed as an integral part of the
Part of what forms a single coil with
Zigzag printed pattern coil of one coil
It has a different width dimension . The other surface of the printed circuit board is a reference potential surface. The zigzag-type printed pattern coil of the low-pass filter has a capacitance between itself and the other surface of the printed circuit board, and forms a kind of self-resonant circuit. Here, if the width dimension of some printed pattern coils is made different from others, a wide self-resonant circuit has a large capacitance between the zigzag type printed pattern coil and the other surface, and a large conductance. So
The resonance frequency is slightly different from the resonance frequency of the self-resonant circuits of the other printed pattern coils, and the Q of the printed pattern coil is increased. Therefore, the low-pass filter including such a printed pattern coil can obtain an amount of attenuation in a wide band in order to cancel each other's resonance frequencies.

According to a second aspect of the present invention, in the high-frequency amplifier according to the first aspect, the printed pattern coil includes:
It is provided with a removable portion for impedance correction. When the printed pattern coil is formed by etching the printed circuit board, even if the value of the inductor or the conductor becomes different from the predetermined value due to, for example, poor etching of the printed pattern portion, by removing the removable portion, the predetermined value can be obtained. Value can be adjusted.

According to a third aspect of the present invention, in the high frequency amplifier according to the first aspect, the print pattern coil of the high-pass filter has a plurality of print pattern portions,
The respective print pattern portions are arranged so that the directions of the magnetic fields generated by the respective print pattern portions are different. For example, a plurality of print pattern portions can be arranged so as to form a substantially right angle. When a plurality of print pattern portions of a print pattern coil are arranged in the same direction, a magnetic field generated from some print pattern portions acts on another print pattern portion, and a magnetic field generated by another print pattern portion is partially generated. And acts on the printed pattern portion to generate mutual inductive coupling. In order to prevent this, the print pattern portions are arranged so that the directions of the generated magnetic fields are different.

According to a fourth aspect of the present invention, in the high frequency amplifier according to the first aspect, the printed pattern coils of the high-pass filter and the low-pass filter are formed so that the directions of the magnetic fields generated by the printed pattern coils are different from each other. It is arranged. For example, the print pattern coil of one filter is a spiral coil, and the print pattern coil of the other filter is a zigzag type.

For example, when the directions of the magnetic fields generated by the print pattern coils of the high-pass filter and the low-pass filter match, the magnetic field generated by one of the print pattern coils acts on the other print pattern coil, and the other print pattern coil. The magnetic field generated by the coil acts on one of the printed pattern coils, causing mutual inductive coupling. To prevent this, the directions of the magnetic fields generated by the printed pattern coils of the high-pass filter and the low-pass filter are different from each other, as in the invention of the fourth aspect.

[0009]

[0010]

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-frequency amplifier according to the present embodiment has
It has an input terminal 2 as shown in FIG. The input terminal 2 is supplied with a first intermediate frequency signal of, for example, a 1 GHz band from a converter attached to a satellite broadcasting or satellite communication receiving antenna, for example. Also, the input terminal 2
Television broadcast signals in the UHF and VHF bands received by terrestrial wave receiving antennas are also supplied.

This high-frequency amplifier includes high-frequency amplification means for amplifying the first intermediate frequency signal, for example, a wide-band amplification IC.
4 and an output terminal 5 are also provided. Between the input side of the amplifying IC 4 and the input terminal 2, a high-pass filter 6 for passing the first intermediate frequency signal is provided via a DC blocking capacitor 7. Further, a high-pass filter 8 for passing the first intermediate frequency signal is provided between the output side of the amplification IC 4 and the output terminal 5 via a DC blocking capacitor 9. As described above, the high-pass filter 6, the amplifying IC 4, and the high-pass filter 8 are cascaded between the input terminal 2 and the output terminal 5. Therefore, only the first intermediate frequency signal passes through the high-pass filter 6 and the amplifying IC 4
And is supplied to the output terminal 5 through the high-pass filter 8.

Further, between the input terminal 2 and the output terminal 5, there is provided a low-pass filter 10 for passing television broadcast signals in the UHF and VHF bands. That is,
A low-pass filter 10 is provided in parallel with the high-pass filter 6, the amplifying IC 4, and the high-pass filter 8. Therefore, UHF and V supplied to the input terminal 2
Only the HF band television broadcast signal passes through the low-pass filter 10 and is supplied to the output terminal 5.

An energizing path 11 is provided for supplying DC power supplied from the output terminal 5 to the input terminal 2. A constant voltage circuit 1 is used to stabilize the DC power drawn from the current path 11 and supply the stabilized DC power to the amplification IC 4.
4 is also provided.

The high-pass filter 6 has capacitors 12, 14, 16, and 18 connected in series between the DC blocking capacitor 7 and the input side of the amplifying IC 4. Also, between the connection point of the capacitors 12 and 14 and the ground point,
The coil 20 is connected. Similarly, the capacitor 14,
The coil 22 is connected between the connection point 16 and the ground point. A series circuit of a coil 24 and a capacitor 26 is connected between a connection point of the capacitors 16 and 18 and a ground point. As described above, the high-pass filter 6 includes only the LC circuit.

The high-pass filter 8 has capacitors 28, 30, 32, and 34 connected in series between the DC blocking capacitor 9 and the output side of the amplifying IC 4. The coil 3 is connected between the connection point of the capacitors 28 and 30 and the ground point.
6 are provided. Similarly, a coil 38 is provided between a connection point of the capacitors 30 and 32 and a ground point. Between the connection point of the capacitors 32 and 34 and the ground point,
A series circuit of a coil 40 and a capacitor 42 is provided. A capacitor 44 is provided in parallel with the series circuit. The high-pass filter 8 is also constituted only by the LC circuit.

In the low-pass filter 10, coils 46, 48, 50, 52, 54 and 56 are provided between the connection point between the DC blocking capacitor 7 and the capacitor 12 and the connection point between the DC blocking capacitor 9 and the capacitor 28. They are connected in series. A capacitor 58 is provided between a connection point between the coils 46 and 48 and a ground point. Similarly, coil 48,
A capacitor 60 is provided between the connection point 50 and the ground point. A series circuit of a capacitor 62 and a coil 64 is connected between the connection point between the coils 50 and 52 and the ground point. A capacitor 66 is connected between a connection point between the coils 52 and 54 and a ground point. Also, the coil 5
A capacitor 68 is connected between the connection points 4 and 56 and the ground point.

The high-frequency blocking coil 7 is connected in series between a connection point between the input terminal 2 and the DC blocking capacitor 7 and a connection point between the output terminal 5 and the DC blocking capacitor 9.
0 and 72. 74 and 76 are arresters.

In the constant voltage circuit 14, the high frequency blocking coil 7
A DC voltage is input from the interconnection point 0, 72 to the constant voltage IC 84 via the diode 78 and the current limiting resistors 80, 82. The output from the IC 84 is supplied to the power supply terminal of the amplifying IC 4 via the Zener diode 86 and the coil 88. The ground terminal of the amplifying IC 4 is connected to a ground point. A load coil 90 is connected between a connection point between the coil 88 and the Zener diode 86 and the output side of the amplification IC 4. 92 and 94 are bypass capacitors.

Such a high-frequency amplifier is formed on a double-sided printed circuit board. One surface of the double-sided printed circuit board is used as a ground potential surface. A printed pattern as shown in FIG. 1 is formed on the other surface 100 of the double-sided printed circuit board. In addition, in FIG. 1, the code | symbol attached between each land is the code | symbol of each above-mentioned element connected between the lands on both sides of the code | symbol. Also,
2a is a connection land of the input terminal 2, 5a is a connection land of the output terminal 5, and G is a ground potential surface.

With such a pattern, the coils 20, 22 in the high-pass filter 6 and the coils 36, 38 in the high-pass filter 8 are formed. These coils 2
Each of 0, 22, 36, and 38 is formed in a rectangular spiral shape as is clear from FIG. These coils 20,
The direction of the magnetic field generated by the current flowing through 22, 22, 38 is perpendicular to the plane of FIG.

The load coil 90 connected between the output side of the amplifying IC 4 and the Zener diode is formed in a zigzag type or a crank type having the same width W. The turn portion 90a on one end side of the coil 90 is short-circuited by a removable portion for impedance correction, for example, a short-circuit portion 90b. Coil 90
Is manufactured by etching. When this etching is performed, a short-circuit portion 90b is provided in order to adjust that the etching has progressed too much and the inductance and conductance have changed from predetermined values. The short-circuit portion 90b is gradually deleted when correcting the impedance.

The coil 4 of the low-pass filter 10
8, 50, 52 and 54 are formed by the above-mentioned printed pattern coils. These coils 48, 5
Each of 0, 52 and 54 is formed in a zigzag type or a crank type in which a plurality of turns are arranged in a zigzag manner. Therefore, the direction of the magnetic field generated by the current flowing through the coils 48, 50, 52, 54 is along the surface of the printed circuit board. On the other hand, coils 20, 22, 36, 38
Since the magnetic field generated by the current flowing in the direction perpendicular to the surface of the printed circuit board, the magnetic field generated in the coils 48, 50, 52, 54 hardly interlinks the coils 20, 22, 36, 38. Conversely, the magnetic fields generated in the coils 20, 22, 36, 38 hardly interlink the coils 48, 50, 52, 54. Therefore, the coils 20, 22, 36, 38,
There is almost no mutual inductive coupling between the coils 48, 50, 52, 54 and no mismatch problem.

The coil 48 has two print pattern portions 48a and 48b. These print pattern portions 48a and 48b form an angle of approximately 90 degrees,
Are located. With this arrangement, the magnetic field generated when a current flows through the printed pattern portion 48a and the magnetic field generated when a current flows through the printed pattern portion 48b are substantially orthogonal. Therefore, the magnetic field generated by the print pattern portion 48a hardly interlinks with the print pattern portion 48b, and the magnetic field generated by the print pattern portion 48b hardly interlinks with the print pattern portion 48a. Therefore, mutual inductive coupling between the print pattern portions 48a and 48b hardly occurs, and the problem of mismatch does not occur.

A short-circuit portion 48a3 for impedance correction is formed at a position biased to one end of the two turn portions 48a1 and 48a2 in the print pattern portion 48a so as to short-circuit them. Similarly, in the vicinity of one end of the turn 48b1 of the printed pattern portion 48b, the short-circuit portion 4 is short-circuited so that the turn portion 48b1 is short-circuited.
8b3 are formed. Further, a short-circuit portion 48b4 is formed on the other end side of the turn portion 48b2. The reason why the short-circuit portions 48a, 48b3, 48b4 are formed is the same as the reason why the short-circuit portion 90b is formed.

The width of the turn portion of the print pattern portion 48b2 is enlarged from the middle, and is equal to the width size of the turn portion of the pattern 50a of the coil 50. The short-circuit portions 50a1, 5a5
0a2 and 50a3 are formed. These short-circuit portions 50
The reason why a1, 50a2, and 50a3 are formed is the same as the reason that the short-circuit portion 90b is formed. A print pattern portion 50b is formed so as to extend over the print pattern portion 50a. This print pattern part 5
0b has a smaller width dimension than the print pattern portion 50a and is formed so as to be biased toward one end of the print pattern portion 50a. Moreover, the width of the coil 5
It is shortened toward the two sides. Of course, the total inductance of the print pattern portions 50a and 50b is a predetermined value.

The coil 52 includes a print pattern section 52
a and 52b. The print pattern portion 52a is also formed so as to be biased toward one end of the print pattern portion 50a, like the print pattern portion 50b of the coil 50. In addition, the width of the print pattern portion 52
The length is increased toward the b side. The turn portions of the print pattern portion 52a also have short-circuit portions 52a1, 52a.
a2 and 52a3 are formed. The print pattern portion 52b has a width slightly longer than the print pattern portion 50a of the coil 50, and also has a short-circuit portion 52b.
b1 is formed. Short-circuit parts 52a1, 52a2, 5
2a3 and 52b1 are provided because the short-circuit portion 90b
Is formed for the same reason. Of course, the total inductance of the print pattern parts 52a and 52b is
It is a predetermined value.

The coil 54 includes a print pattern unit 54
a and 54b, which are arranged at an angle of substantially 90 degrees, like the print pattern portions 48a and 48b of the coil 48. Arranged in this manner is that the printed pattern portion 48a of the coil 48,
This is for the same reason that the 48b is arranged at a right angle. Also,
Short-circuit part 5 in one turn part of print pattern part 54a
4a1 are formed. This is provided,
This is the same reason that the short-circuit portion 90b is formed.

As described above, the print pattern portion 50b of the coil 50 and the print pattern portion 52 of the coil 52
“a” is formed to be shorter in width than the print pattern portion 50a of the coil 50 and the print pattern portion 52b of the coil 52. These print pattern portions 50a, 50
b, 52a and 52b are formed on one surface of the double-sided printed circuit board, and the other surface is a ground potential surface. Accordingly, a capacitance and a conductance are formed between each printed pattern portion and the ground potential surface, and the printed pattern portions 50a, 50b, 52a, 52b also function as a self-resonant circuit.

Then, the print pattern portions 50a, 52
Since the width dimension of b is wider than the width dimensions of the print pattern parts 50b and 52a, it is easy to have a capacity and the inductance is large. As a result, Q of the print pattern portions 50a and 52b is
2b, and their self-resonant frequencies are
This will deviate from the self-resonant frequency of the print pattern portions 50b and 52b. As a result, the print pattern unit 5
The self-resonant circuit constituted by Oa and 50b and the self-resonant circuit constituted by the printed pattern portions 52a and 52b can attenuate a high-frequency signal input in a wide frequency band. The print pattern units 50b, 52a
Is biased toward one end of the print pattern portion 50a, but may be biased toward the other end of the print pattern portion 50a.

FIG. 3 shows the frequency vs. gain characteristics of the high-frequency amplifier. As is clear from this figure, about 7
Up to about 80 MHz, only the insertion loss of the low-pass filter 10 is attenuated, and the UHF and VHF television broadcast signals input to the input terminal 2 pass through the low-pass filter 10 and are output to the output terminal 5. Is done. Further, a gain of about 22 to 23 dB is obtained from about 900 MHz to 1700 MHz. Therefore, only the first intermediate frequency signal of the satellite broadcast or the satellite communication supplied from the input terminal 2 is transmitted through the high-pass filter 6 to the amplification I signal.
The signal is supplied to C4, amplified here, and only these amplified signals are output to the output terminal 5 via the high-pass filter 8.

FIG. 4 shows the effect of temperature change on the frequency vs. gain characteristics of this high-frequency amplifier.
In the case of degrees, +20 degrees, and -20 degrees, the gain is hardly affected.

In the above embodiment, the high-pass filter 6
Is provided on the input side of the amplifying IC 4 and the high-pass filter 8 is provided on the output side of the amplifying IC 4, but only one of them may be provided.

[0034]

As described above, according to the first aspect of the present invention, the high-pass filter and the low-pass filter have the printed pattern coils formed on the printed circuit board on which the high-frequency amplifier is formed. Since it can be formed at the same time when the print pattern for the amplifying means is formed, the production becomes easy. In addition, since these pattern coils can easily have a desired inductance, when air-core coils are used, the necessary adjustment is almost unnecessary, and the cost can be reduced. Furthermore, it is formed on one side of a double-sided printed circuit board
The predetermined inductance of the low-pass filter
Multiple zigzag puddings forming one coil
Some of the pattern coils have the same coil
The width dimension differs from the zigzag type printed pattern coil.
Yes allowed al, the other surface of the printed circuit board is a reference potential surface. These printed pattern coils constitute a self-resonant circuit, but the Q of the self-resonant circuit formed by some of the printed pattern coils increases, and the self-resonant frequency also increases.
Different from others. Therefore, the combined self-resonant circuits composed of these printed pattern coils cancel each other's resonance frequencies, and thus can attenuate the input signal over a wide band.

According to the second aspect of the present invention, since the printed pattern coil is formed with the removable portion for impedance correction, a desired inductance or conductance can be obtained when the printed pattern coil is formed by etching. Even if it is not possible, by gradually removing the removable portion, the desired inductance and conductance can be easily adjusted.

According to the third aspect of the present invention, the plurality of print pattern portions of the print pattern coil of the high-pass filter are arranged such that the directions of the generated magnetic fields are different from each other.
There is almost no mutual inductive coupling between them, and there is no problem of mismatch.

According to the fourth aspect of the present invention, the high-pass filter and the low-pass filter are arranged such that the directions of the magnetic fields generated by the printed pattern coils of the high-pass filter and the low-pass filter are different from each other. There is no mutual inductive coupling between them and no mismatch problem.

[0038]

[Brief description of the drawings]

FIG. 1 is a pattern diagram of an embodiment of a high-frequency amplifier according to the present invention.

FIG. 2 is a circuit diagram of the embodiment.

FIG. 3 is a frequency-gain characteristic diagram in the embodiment.

FIG. 4 is a diagram showing a change in frequency versus gain characteristic with temperature in the embodiment.

[Explanation of symbols]

4 IC for amplification (high frequency amplification means) 6 8 High-pass filter 10 Low-pass filter 2236 Print pattern coil 48a 48b 50a 50b 52a 52b 52b 5
4a 54b Print pattern portion 48a3 48b3 48b4 50a1 50a2
50a3 52a152a2 52a3 52b1 5
4a1 Short-circuit part (removable part for impedance correction)

Claims (4)

(57) [Claims] A high-frequency amplifying means configured on a printed circuit board; a high-pass filter cascaded to at least one of an input side and an output side of the high-frequency amplifying means and configured on the printed circuit board; A low-pass filter connected to the amplifying unit and the high-pass filter in parallel with the high-pass filter and configured on the printed board, wherein the high-pass filter and the low-pass filter are printed pattern coils configured on the printed board. The printed circuit board is a double-sided printed circuit board, and the low-pass filter has a plurality of zigzag-type printed pattern coils formed on one surface of the printed circuit board, and the zigzag-type printed pattern
A predetermined inductor formed by the coil
Part of what forms one coil with a closet is
The other zigzag print pattern of one coil
A high-frequency amplifier, wherein the width of the printed circuit board is different from that of the printed circuit board, and the other surface of the printed circuit board is a reference potential surface. 2. The high-frequency amplifier according to claim 1, wherein
The high-frequency amplifier according to claim 1, wherein the printed pattern coil has a removable portion for impedance correction. 3. The high-frequency amplifier according to claim 1, wherein
The high-frequency amplifier according to claim 1, wherein the print pattern coil of the high-pass filter has a plurality of print pattern portions, and each of the print pattern portions is arranged so that the direction of the magnetic field generated by each of the print pattern portions is different. 4. The high-frequency amplifier according to claim 1, wherein
A high-frequency amplifier, wherein the printed pattern coils of the high-pass filter and the low-pass filter are arranged such that the directions of the magnetic fields generated by the high-pass filter and the low-pass filter are different from each other.