JPH0918244A - High frequency amplifier - Google Patents

Abstract

PURPOSE: To provide a high frequency amplifier which can decrease the linear distortions and can increase its working band by providing a multi-peak resonance circuit that has a low Q. CONSTITUTION: The transistors TR 10 and 12 function as the grounded-emitter amplifiers. A load resistor 24, the pattern inductors 26 and 28, a pattern inductor 18, a base resistor 16 and the base-collector capacity of the TR 10 are connected to the collector of the TR 10. Furthermore, the capacitors 50, 48 and 21 are added together with the floating capacity Ca and the lead inductance of the resistor 24. In such a constitution, a resonance circuit is obtained. The capacity of the capacitor 48 is increased, and the inductors 18, 26 and 28 are set at a reference potential respectively in terms of high frequency. These inductors and the component of capacity Ca construct plural resonance circuits with the low Q and in the wide bands. Thus the preceding resonance circuit also has a low Q and can secure the flat frequency characteristic since the indictors 18, 26 and 28 have the low Q due to the influences of the resistors 16, 24, etc. In the same way, the TR 12 also has its flat frequency characteristic and can increase its working band.

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,
In particular, it relates to a broadband high frequency amplifier.

[0002]

2. Description of the Related Art A high frequency amplifier for amplifying a high frequency signal of about 1 GHz or higher, which has a relatively narrow band,
For example, as shown in FIG. 6, there is a multi-stage cascade connection of grounded-emitter circuits that use a series circuit of a resistor 2 and an inductor 3 as a load. In the figure, 4 is a transistor for high frequency amplification whose grounded emitter is connected, 6 is a biasing base resistor, and 7 is a DC blocking capacitor.

The high frequency amplifier as shown in FIG. 6 is designed to be suitable for amplifying a high frequency signal in the frequency band of 1035 MHz to 1550 MHz, for example, and is about 5
With a bandwidth of 00 MHz, flat frequency characteristics without linear distortion can be obtained. However, in recent years, signals transmitted from communication satellites have been received and frequency-converted from 950 MHz to 18 MHz.
There is an increasing need to amplify intermediate frequency signals in the wide band of 80 MHz. In order to adapt to such a case, when the constants of the resistor 2 and the inductor 3 of the high frequency amplifier shown in FIG. 6 were changed, the frequency characteristic as shown in FIG. 7 was obtained.

[0004]

As is apparent from FIG. 7, when the high frequency amplifier shown in FIG. 6 is intended to be broadened to a higher frequency side than before, the constants of the resistor 2 and the inductor 3 are changed. Only by doing so, a large low-gain depression is generated in the required frequency band as indicated by the symbol α, and the linear distortion becomes large. This is because the value of the inductor 3 is forcibly reduced, the band is widened to the high frequency side, and the Q of the inductor 3 is increased in order to increase the gain at the widened high frequency, for example, 1880 MHz. This is because a peak has occurred. Many signals from communication satellites are digital signals, and when they are processed after demodulation, it is not preferable that they are affected by linear distortion, which causes various troubles.

It is an object of the present invention to provide a high-frequency amplifier having a flat frequency characteristic over a wide band at a high frequency of about 1 GHz or more and having stable characteristics with little linear distortion. Further, the present invention is, for example, about 1G.
An object of the present invention is to provide a high frequency amplifier having a tilt characteristic at a high frequency of Hz or higher.

[0006]

In order to achieve the above object, the first aspect of the present invention is such that a power supply line and a reference potential line, a control electrode and an output electrode, which are provided on a printed circuit board, respectively have resistances. Connected to the power supply line through the resistor, the common electrode is connected to the reference potential line, and the connection between each resistor and the power supply line is a pattern inductor formed on the printed circuit board. The capacitor means is provided between each pattern inductor and the reference potential line in a state of forming a multimodal resonance circuit together with the pattern inductor. Second
According to the invention, a plurality of the high frequency amplifiers of the first invention are connected in cascade.

Further, in the third invention, in the first invention, the capacitance means includes a stray capacitance formed between the pattern inductor and the reference potential line.

[0008]

According to the first aspect of the present invention, since the multi-peak resonance circuit constituted by the pattern inductor and the capacitance means is connected to the output electrode side of the transistor, the output signal obtained from the output electrode is It has characteristics. The pattern inductors forming this multimodal resonance circuit originally have a low Q, and since resistors are connected to these pattern inductors, the Q further decreases. Therefore, a multimodal resonance circuit having a very low Q is formed, so that a wide band can be achieved. When a plurality of cascade connections are made as in the second invention, a wide band can be achieved and
The gain can be increased.

According to the third aspect of the present invention, since at least a part of the capacitance means is formed by the stray capacitance, it is not necessary to provide a special capacitance means.

[0010]

1 is a circuit diagram of an embodiment of a high frequency amplifier according to the present invention. The high frequency amplifier of this embodiment has an NPN
It is a two-stage cascade-connected grounded-emitter amplifier using silicon transistors 10 and 12.

A common electrode of the transistor 10, for example, an emitter is connected to a reference potential line, for example, a ground potential point,
A high-frequency signal in the 1 GHz band, for example, is supplied to the control electrode, for example, the base, via the DC blocking capacitor 14. The base of the transistor 10 is connected to a power supply line 22, for example, a potential point of + V, via a base resistor 16, a pattern inductor 18 described later, a resistor 20 and a capacitor 21 connected in parallel. Further, the output electrode of the transistor 10, for example, the collector, is connected to the power supply line 22 via the load resistor 24, the pattern inductors 26 and 28 connected in parallel, the resistor 20 connected in parallel, and the capacitor 21.

The collector of the transistor 10 is connected to the base of the transistor 12 via the DC blocking capacitor 30. This base is connected to the power supply line 22 via base resistors 32 and 34 connected in series. Further, it is also connected to the power supply line 22 via the resistor 32, a pattern inductor 36 described later, and a resistor 38.

The emitter of the transistor 12 is grounded,
The collector is connected to the power supply line 22 via the resistor 40, the pattern inductors 42 and 44 connected in parallel, which will be described later, and the resistor 38 described above. The collector of the transistor 12 is connected via a capacitor 46 to an amplifier (not shown) in the subsequent stage.

Further, the resistor 16 and the pattern inductor 1
Between the interconnection point with 8 and the reference potential point, capacitive means,
For example, the capacitor 48 is connected, and similarly, the capacitor 50 is also connected between the interconnection point between the pattern inductor 26 and the resistor 24 and the reference potential point. Further, the capacitor 52 is connected between the interconnection point of the resistors 34 and 32 and the reference potential point, and the pattern inductors 36 and 4 are connected.
The capacitor 54 is also connected between the interconnection point between the resistors 2 and 44 and the resistor 38 and the reference potential point. A capacitor 55 is also connected between the connection point between the resistor 38 and the power supply line 22 and the reference potential point.

Further, such a high frequency amplifier is formed on a printed circuit board, for example, a double-sided printed circuit board made of glass epoxy. As a result, pattern inductor 1
It is equivalent to the stray capacitance Ca being connected between the interconnection point of 8, 26, 28 and the reference potential point. Similarly, it is equivalent to the stray capacitance Cb being connected between the interconnection point between the pattern inductors 42 and 44 and the resistor 40 and the reference potential point.

Such a high frequency amplifier is formed on a printed circuit board 60 as shown in FIG. 2, for example. The printed circuit board 60 is, for example, a double-sided printed circuit board made of glass epoxy, and has a thickness of 1.6 mm and a relative dielectric constant of 4.
The thickness of each pattern formed on this substrate is 35 μm.

The metal foil on one surface (not shown) of the printed circuit board 60 is used as a reference potential surface,
A pattern as shown in FIG. 2 is formed on the other surface and is used for connecting the above-mentioned respective parts to each other.

As shown in FIG. 2, lands 62 for inputting high frequency signals are formed in the pattern.
A land 64 for connecting the base of the transistor 10 is also formed adjacent to the land 62. Between the lands 62 and 64, for example, a capacitor 1 of 10 pF
4 are connected. A reference potential land 66 to which the emitter of the transistor 10 is connected is also formed. A land 68 to which the collector of the transistor 10 is connected is also formed.

Then, the base resistor 16 and the load resistor 2
A relay land 70 for connecting the base and collector of the transistor 10 to the power supply line 22 via the transistor 4 is provided between the land 64 and the land 68. The base resistor 16 is connected between one end of the relay land 70 and the land 64, and the load resistor 24 is connected between the other end of the relay land 70 and the land 68. There is.

Between these ends, the pattern inductor 1
8, 26 and 28 are formed. The pattern inductor 18 is formed to have a width of about 1 mm and a length of about 3 mm, and the pattern inductor 26 has a width of about 0.5 mm.
mm, and the length is about 2 mm. The pattern inductor 28 is an inverted L-shape connected in parallel with the pattern inductor 26 and has a width of about 0.5 mm.
The length is about 4 mm and 6 mm. Since the lengths and widths are set as described above, the inductances of the pattern inductors 18, 26, 28 are several n, respectively.
It becomes H to ten and several nH. These pattern inductors 1
Since 8, 26, and 28 are formed by the pattern, they have a low Q originally, but since the resistor 20, the base resistor 16, and the load resistor 24 are respectively connected, Q dump is performed. , Even lower Q.

A capacitor 48 is connected between a portion of the relay land 70 near the portion to which the base resistor 16 is connected and the reference potential land 66. The capacitor 48 has a large capacity of 1000 pF, for example. Further, the capacitor 50 is also provided between the vicinity of the portion where the pattern inductors 26 and 28 are provided and the reference potential land 66. The capacitor 50 has a capacitance of 1 pF, for example.

The land 7 corresponding to the power supply line 22
2 is provided, and the resistor 20 and the capacitor 21 are provided near this and the pattern inductors 26 and 28 of the relay land 70. The capacitor 21 has a capacitance of 10 pF, for example.

Further, in the vicinity of the land 68, a land 74 for supplying the collector output of the transistor 10 to the base of the transistor 12 is provided. Between one end of the land 74 and the land 68, for example, 1.
A 5 pF DC blocking capacitor 30 is connected. In addition, the transistor 1 is provided at the other end of the land 74.
2 bases are connected. The emitter of the transistor 12 is connected to the reference potential land 66. The collector of the transistor 12 is connected to one end of the collector connection land 76. The other end of the land 76 and the output land 7 adjacent to the other end
8 and a DC blocking capacitor 46 of 1 pF, for example.
Is connected.

Between the middle of the land 74 and the middle of the land 76, a detoured power relay land 80 is provided. The base resistor 32 is connected between the middle of the land 74 and one end of the land 80. Land 80
Between the middle of the line and the reference potential land 66, for example, 1000
A pF capacitor 52 is connected. The load resistor 40 is connected between the other end of the land 80 and the middle of the land 76.

The relay land 80 is provided with pattern inductors 36, 42 and 44. The pattern inductor 36 has, for example, a width of about 1.5 mm and a length of about 5.6 mm. In addition, the pattern inductor 42
Has a width of about 0.5 mm and a length of about 3 mm. The pattern inductor 44 is connected in parallel with the pattern inductor 42 and has a width of about 0.5 mm and a length of about 5.5 mm.
And 4 mm L-shaped. Since the length and width are set in this way, the pattern inductors 36, 42,
The inductance of 44 is several nH to ten and several nH.
These pattern inductors 36, 42, and 44 have low Q, and resistors 32, 34, and 40 are respectively connected, so that the Q is even lower.

The resistor 34 is connected between the vicinity of the end of the pattern inductor 36 and the power supply line pattern 72, and the end of the power supply line 72 and the connection between the pattern inductors 42 and 44 in the relay land 80 are connected. A resistor 38 is connected in between. Further, a capacitor 54 of, for example, 1000 pF is connected between this connection portion and the reference potential land 82. Further, a capacitor 55 of 1000 pF, for example, is connected between the land 72 and the reference potential land 82.

In the high frequency amplifier configured as described above,
Both transistors 10 and 12 amplify as a grounded-emitter amplifier. And, for example, in the transistor 10,
A load resistor 24 and pattern inductors 26 and 28 are connected to its collector, and the pattern inductor 1
8, the base resistor 16, the base of the transistor 10 and the collector capacitance are also connected. In addition to these, capacitors 50, 48 and 21, stray capacitance Ca, and lead inductance of the resistor 24 are also added to form a resonance circuit. In particular, since the capacitance of the capacitor 48 is as large as 1000 pF, the pattern inductors 18, 26 and 28 are at the reference potential in terms of high frequency. And the pattern inductor 1
8, 26 and 28 form a plurality of resonance circuits together with a stray capacitance component represented by a stray capacitance Ca. That is,
The pattern inductors 18, 26 and 28 are considered to be distributed constant lines, and have a low Q as compared with a resonance circuit composed of lumped constant elements. Since a plurality of such resonance circuits having a low Q are formed, it is advantageous for widening the band. Since the pattern inductors 18, 26, 28 have a very low Q due to the influence of the resistors 16, 24, etc. as described above, this resonant circuit also has a very low Q.

Since this resonance circuit is a bimodal resonance circuit, it has a plurality of resonance circuits. Although it is difficult to clearly separate what kind of elements the plurality of resonance circuits are composed of, it is (a) a resonance circuit formed by the lead inductance of the resistor 24 and the capacitor 50 when intentionally performed in order to explain the principle. (B) Pattern inductor 2
6, a resonance circuit composed of the stray capacitance Ca and the a, a resonance circuit composed of (c) the pattern inductor 28, the capacitor 21 and the a, and (d) a resonance circuit composed of the a, b and c, the pattern inductor 18 and the capacitor 48. However, each is considered to exist. Each of these resonance circuits constitutes a low Q load resonance circuit as indicated by reference characters A to D in FIG. 3A, and these are combined to obtain a substantially flat frequency characteristic as shown in FIG. 3B. Will have. Similarly, the frequency characteristic of the transistor 12 is flat.

FIG. 4 shows frequency characteristics in a state where three high frequency amplifiers similar to the high frequency amplifier shown in FIG. 1 are connected in cascade. As is clear from this frequency characteristic, a substantially constant gain is obtained from 800 MHz to 2000 MHz, and the frequency characteristic is flattened up to a high frequency. Since the frequency characteristic is flat as described above, linear distortion is small. Moreover, since the same parts as those conventionally used are used, the cost does not increase. Further, the tilt characteristics as shown in FIG. 5 can be provided by changing the circuit constants, for example, the length, width, shape of each pattern inductor and the capacitance of each capacitor. To obtain such tilt characteristics, for example, the capacitor 50 is removed and the pattern inductors 18, 26,
28 and these stray capacitance components form a resonance circuit, and the pattern inductor 36 has a width of 0.5 mm and a length of 3 m.
and the width of the pattern inductor 44 is 0.5 m.
m, and L-shaped with lengths of 4 mm and 3 mm. With this configuration, for example, the transistor 10,
In each of the 12-sided bimodal resonance circuits, the peak value at the low resonance frequency decreases and the peak value at the high resonance frequency increases. As a result, tilt characteristics occur.

In the above embodiment, three pattern inductors are used in the one-stage high-frequency amplifier, but by increasing the number of them and changing their length, width and shape, and arranging capacitors appropriately. Further, it is possible to further widen the band. Further, in the above embodiment, the capacitor and the stray capacitance were used as the capacitance means, but it is also possible to use only the stray capacitance. In this case, since the capacitor is not needed, the cost can be reduced.
Further, in the above-mentioned embodiment, the high frequency amplifiers connected in cascade in two stages are shown, but it is also possible to use one stage of high frequency amplifiers.

[0031]

As described above, according to the first aspect of the invention, since the multimodal resonance circuit including the circuit in which the pattern inductor having a low Q and the resistor are connected in series is used, the It is possible to realize a high-frequency amplifier having a low bimodal resonance circuit, flat frequency characteristics up to high frequencies, and little linear distortion. Further, the tilt characteristic can be realized by selecting the circuit constant. further,
Since a pattern inductor is used to achieve such a wide band, it is not necessary to use a special component, and there is no particular increase in cost for realizing a wide band and tilt characteristics. According to the second aspect of the invention, since the plurality of high frequency amplifiers according to the first aspect of the invention are connected in cascade, it is possible to increase the gain while achieving a wider band. According to the third aspect of the invention, since the stray capacitance is used as the capacitance means, it is not necessary to provide a special capacitor, and the cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a circuit pattern diagram of the embodiment.

FIG. 3 is an explanatory diagram of a reason why a wide band can be achieved in the embodiment.

FIG. 4 is a gain vs. frequency characteristic diagram in the embodiment.

FIG. 5 is a gain vs. frequency characteristic diagram in a modified example of the same embodiment.

FIG. 6 is a circuit diagram of a conventional high frequency amplifier.

7 is a gain vs. frequency characteristic diagram when a constant is changed in the high frequency amplifier of FIG. 6 to achieve a wider band.

[Explanation of symbols]

10 12 transistor 16 24 32 40 resistor 18 18 26 28 36 42 44 pattern inductor 60 printed circuit board 72 power supply line land 66 82 reference potential land

Claims (3)

[Claims] 1. A transistor in which a power supply line and a reference potential line provided on a printed circuit board, a control electrode and an output electrode are respectively connected to the power supply line via a resistor, and a common electrode is connected to the reference potential line. And
The connection between each of the resistors and the power supply line is performed via a pattern inductor formed on the printed circuit board, and the pattern inductor and the reference are formed in a state of forming a multimodal resonance circuit together with the pattern inductor. A high frequency amplifier in which a capacitance means is provided between the potential line and the potential line. 2. A high-frequency amplifier comprising a plurality of the high-frequency amplifiers according to claim 1 connected in cascade. 3. The high frequency amplifier according to claim 1, wherein
The high-frequency amplifier, wherein the capacitance means includes a stray capacitance formed between the pattern inductor and the reference potential line.