JPS5837139Y2 - High frequency high power transistor amplifier - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a high-frequency, high-output transistor amplifier, and particularly to the structure of an IC-based power amplifier in the UHF band.

Recently, the development of high-frequency, high-output transistors has progressed, and efforts are being made to use them to solidify high-frequency power devices.

For example, a transistor amplifier with a saturation output of about 20W is
The development of a UHFTV satellite station transmitter with an output of several hundred W by combining several transmitters is progressing.

However, the input impedance value of high-frequency, high-output transistors is generally very small, making it extremely difficult to construct a broadband matching circuit.

That is, since the impedance resistance component is usually a few Q or less, the Q value of the circuit becomes large even by a small amount of actance, resulting in a drawback that the bandwidth is limited.

Such a high-output transistor amplifier requires a matching circuit with a large impedance conversion ratio, and to construct this, an extremely low impedance line or an extremely large capacitance element must be used.

However, with the conventional so-called microwave IC technology, that is, the hybrid IC technology that uses a microstrip line using an alumina substrate and a chip capacitor, it is difficult to realize the above-mentioned circuit well at high frequencies.

Particularly in the UHF band, the wavelength on the microstrip circuit is several tens of centimeters, and in order to downsize it to a practical size, it is necessary to lump constants in some parts.

However, on the other hand, conventional thin film LC elements and chip capacitor elements laminated with high dielectric constant materials do not have the necessary element values and high frequency characteristics. It was not possible to realize a practical high-frequency, high-output transistor amplifier because it was not possible to satisfy the essential conditions of suppressing heat generation in active elements such as transistors, and minimizing changes in thermal characteristics in consideration of heat generation in active elements such as transistors. There wasn't.

The purpose of the present invention is to provide a high frequency, high power transistor amplifier which can solve the problems outlined above, has significantly improved electrical characteristics, cost, reliability, etc., and is usable for practical use.

According to the present invention, the input/output matching circuit power XCLa2Ti2O7]y includes a transistor provided on a ground conductor and at least one or more parallel capacitors connected to the transistor or at least one or more wavelength impedance conversion lines.
C3r2Nb207]zC8Mg2CLTi(2-+C
L) O(+-2(1c))] (where X+y+z=1) with the composition O<xil, o, o<y<o, 9. o*z<1.
I on a dielectric substrate made in the range o, o≦α 1°
A high frequency, high output transistor amplifier is obtained, which is characterized in that it is made of C.

An example of the measured characteristics of a dielectric substrate made with the above composition is shown in the first example.
Shown in the table.

The dielectric constant and dielectric loss were measured at a frequency of IMHz, and the temperature coefficient was determined based on the dielectric constant value measured at -30°C, 0°C, +25°C, and 60°C, and based on the dielectric constant value at 125°C. .

Generally, it is thought that almost the same characteristics are exhibited in the UHF band and the microwave band.

Table 2 shows a comparison of the properties with alumina, which has been commonly used in the past.

As is clear from Table 1, the characteristics of the dielectric substrate used in the present invention are that it has a high dielectric constant over the entire composition range and has a tan δ of 10. It is as small as lX10-4, and the temperature coefficient is less than ±500 ppm/'C, and -30
Even in an environment of ℃ to +60℃, the change range of εr is 5%.
In the following, this value is the change range of the element value as it is, and is a sufficiently small value that does not cause any practical problems.

The effective range of the invention is that the temperature change becomes large when y≧0.9, and the dielectric constant is small when Z = 1.0, so the composition of an effective dielectric substrate for high-frequency, high-power transistor amplifiers is 0< x <1.0.0 <y<0.9.
It is desirable that there be a range of O<Z<1.0.

Therefore, the basic composition of the high dielectric constant substrate of the present invention is L
It is shown that it is composed of three types of composite phases: a2Ti2O7, 5r2Nb207, and MgTiO3.

However, for MgTiO3, it means that the proportion of the existing phase differs depending on the composition ratio of MgO and TiO2 depending on the range of α. For example, when α = 0, TiO
2, indicating that when α-1, only MgO is present.

Also, in Table 1, No. 4. No, 32. No
, 33°No, 34, examples of characteristics with composition ratios outside the limited range are also shown, but the temperature coefficient of εr becomes large (No, 4), and εr becomes small (No, 3).
4) Do.

The substrate materials with compositions No. 32, No. 33 are two-component substrates, and have shown superior electrical performance compared to other two-component and three-component materials. It is unsuitable for use as a high-frequency circuit board due to mechanical strength requirements, such as transverse rupture strength, water absorption, and surface roughness.

The dielectric constant at 400 MHz was measured using the slot line method and showed almost the same value as the value at IMHz.

Next, the principle, operation, and effects of the present invention will be explained in detail using drawings showing embodiments.

FIG. 1 is a diagram showing a first embodiment of the present invention, and a is a plan view;
b is its equivalent circuit.

In the figure, high dielectric constant substrates (sample No. in Table 1,
5) Input and output circuits are integrated into ICs on 2 and 2', and these are housed in a case 4 that also serves as a ground conductor, forming a UHF high-output transistor amplifier with input and output connectors 5 and 5'. There is.

The input side matching circuit is Ll. A wavelength transformer Z1 and an adjustment capacitor C1 are further added to the low-pass type circuit formed by L2.C2, and the output side matching circuit is formed by L2. C3, L3. It is composed of a C4 low-pass type circuit.

In addition, C8 is a DC block or RF short circuit capacitor, Zo
TB and Tc are base and collector terminals, and E is a ground terminal.

The back surface of the entire board is a ground conductor, and the ground terminal E is also connected to this.

CT 19 manufactured by CTC in the U.S. with 20W output in the UHF band.
Taking a 331-transistor as an example, its output impedance resistance components are, for example, 1°25Ω, 3.
3,,Q, and the element values of the matching circuit shown in FIG. 1, which converts this into 50Ω at a frequency of 600 MHz and a fractional band of about 40%, are as follows, for example.

Lt=0.5nHyCt=134pF, Zt=140°Lt=1.88nH, Cm=43pF, Ls=7-3n
HL4 = 11.3 pF Here, capacitances C2 and C3 are the Tr and the inductor L before and after it.
,, A large capacitance value is required to perform impedance conversion while keeping the Q value with L2 low.

However, normally used chip-type multilayer ceramic capacitors or thin film capacitors cannot be used because such large capacitance values cause self-resonance in the UHF band.

Particularly in the case of high-output applications, a self-inductance of several nH is unavoidable due to dimensions.

In this respect, a single-plate capacitor in which one electrode serves as a ground conductor is optimal, and a high dielectric constant substrate is suitable for obtaining a large capacity.

If the thickness of each plate is 0.25 mm like the substrate 2 in FIG. 1, about 100 pF can be obtained in about 10 m2.

Moreover, it is advantageous in terms of cost and man-hours if this capacitor substrate is used as an IC substrate and is formed as an IC together with C3°C4 or C1 and C2 on the same substrate.

In FIG. 1, an impedance conversion line with a wavelength of 200 nm is used, but such a converter is often used in a broadband matching circuit.

In Fig. 1, this transducer beam is approximately 4Ω due to C.
In order to convert the Tr input side impedance to 50Ω, a characteristic impedance of approximately 14Ω is required.
High power transistor amplifiers such as this example require extremely low characteristic impedance lines.

Now, if we compare the line width when realizing a characteristic impedance line of 5 to 20 Q using a conventional alumina substrate and the above-mentioned high dielectric constant substrate of the present invention, when the plate thickness is Q and 5 mm, the line width is as follows. Become.

Therefore, in the case of a conventional alumina substrate, 10. It is very difficult to use a line of about Q.

Furthermore, this converter requires a wavelength of
For example, when taking the F band of 600 MHz as an example, the length of the wavelength is 50 mm in the case of alumina and 25 mm in the case of the high dielectric constant substrate according to the present invention.

Therefore, in this case as well, it is very difficult to form an amplifier within a practical dimension of several centimeters using an alumina substrate.

By using the high dielectric constant substrate of the present invention, it is possible to realize a low impedance line with a capacity approximately 3 to 10 times larger than that of conventional alumina-based IC circuits and a small area. It is possible to easily realize a UHF band power transistor amplifier with a practical size, wide band, and high performance.

Note that in the first embodiment, the series inductor L2 . L3 is also formed on a high dielectric constant substrate, which is easy to manufacture, but on the other hand, these inductors have a large parallel capacitance and are close to distributed constant lines, so it is necessary to make them smaller or increase the Q value. In order to create a lumped constant inductor, it is necessary to increase the impedance to ground as much as possible.

Another embodiment that improves this point will be shown next.

FIG. 2 is a plan view showing a second embodiment of the present invention.

In FIG. 2, the same symbols as in FIG. 1 indicate the same components.

Furthermore, three-stage low-pass matching circuits are formed on both sides of the high-frequency, high-output transistor 1 to form an amplifier. Single plate capacity 21, 22, 23 and 21
', 22', and 23' are formed to form a parallel capacitor.

Naturally, the entire invisible side surface of the high dielectric constant substrates 2, 2' serves as a ground plane.

In this embodiment, the series inductors connected to these capacitors at the substrate boundaries are placed on other dielectric substrates 3 and 3' as 31, 32, 33 or 31',
32'.

33'.

4 is the amplifier case, 5゜5' is the input/output connector, 6, 6
' is a DC block capacitor, and 7 and 7' are bias choke circuits.

In this embodiment, as in the first embodiment, a capacitor with extremely large capacity and suitable for high frequencies can be easily obtained by simply forming separated electrodes on a high dielectric constant substrate using IC technology.

On the other hand, if conventional IC dielectrics such as alumina and quartz are used as the dielectrics 3 and 3', the impedance of the inductor line can be made sufficiently large, resulting in excellent high frequency characteristics. I can do it.

FIG. 3 is a diagram showing a third embodiment of the present invention, in which a is a plan view and b is a partially enlarged perspective view.

In this embodiment as well, parallel capacitances 20 and 20' are formed on the high dielectric constant substrates 2 and 2' as in the previous embodiments, but the inductor inserted in series with these is another chip-shaped dielectric. Chip type inductor 30 formed on the body
．． 30' is used.

Figure b is an enlarged view of the chip inductor.
' is formed into a conductive pattern, and the chip is directly placed on the capacitor electrode 20 and connected.

A large capacity can be obtained between the high dielectric constant substrate and the ground conductor 29 on the back surface.

In addition, the unnecessary parallel capacitance of the inductor 36, 36' is mainly determined by the dielectric substrate 35, 35' of the chip, and an inductor with excellent high frequency characteristics can be obtained, making it possible to realize a compact, high-performance, high-frequency, high-output transistor amplifier. Ta.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, in which a is a plan view and b is an equivalent circuit diagram thereof. In the figure, 1 is a transistor, 2, 2' are high dielectric constant electric substrates, 4 is a case, 5.5' is an input/output connector, C1, C2, C3, C4 are parallel capacitors, Ll, L2.
L3 is a series capacitor, Zl is a wavelength converter, co is a DC block, RF short capacitor, and Zo is a choke line. FIG. 2 is a plan view showing a second embodiment of the present invention, in which the same components as in FIG. 1 are designated by the same numbers. 3, 3' are different dielectric substrates, 21 to 23. 21' to 23
' is a parallel capacitance, 31 to 33, and 31' to 33' are series inductors. FIG. 3 shows a third embodiment of the present invention, in which a is a plan view and b is a partially enlarged perspective view. 20 to 20' are parallel capacitors, 30 to 30' are chip type inductors, 35.35' are chip type dielectrics, 36.36'
indicates the inductor conductor.

Claims (1)

[Scope of utility model registration request] The transistor provided on the flat ground conductor and the
2T1207) 'l C3r2Nb207:] Z
('z Mg2aTl (2-211)OC+-2g)
] (where X+V+Z=1) and 0≦x<1.0.
It is made in the range of 0≦V<0.9.0≦z<1.0.0≦α<1.0, and the relative permittivity (εr) is 28 or more, and the temperature coefficient range of the relative permittivity is ± 500 ppm/'c or less and at least one dielectric substrate connected to the transistor.
A plurality of parallel single-plate capacitor elements sandwiching the dielectric substrate and a wavelength impedance conversion circuit are formed into an IC on the dielectric substrate, and an IC provided on the ground conductor.
A high frequency, high output transistor amplifier characterized in that it is integrated with a C input/output matching circuit.