JP2956135B2 - High frequency power amplifier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a push-pull high-frequency power amplifier.

[Conventional technology]

In a push-pull high-frequency power amplifier, amplifier elements such as bipolar transistors and field-effect transistors can be used at various operating points such as class A, class B, and class C.
FIG. 6 shows an example of this type of amplifying device using bipolar transistors.

In the figure, a pair of push-pull bipolar transistors Q and Q 'have a pair of input terminals 2 and 2' and a pair of output terminals 3 and 3 'and have a common ground terminal 4. In the high-frequency amplifier 1 including these transistors Q and Q ′, the input power input from the high-frequency input terminal 5 is converted into balanced power by the balanced-unbalanced converter 8.
Input is made to each input terminal 2, 2 'through a matching circuit consisting of strip lines 10, 10' and a capacitor 12. The power-amplified output is output from output terminals 3, 3 'through a matching circuit including strip lines 11, 11' and a capacitor 13, and a balun converter 9.

7 is a power supply terminal, 14 and 15 are choke coils, and 16 and 17
Is a capacitor.

This push-pull type high frequency amplifying device is disclosed in a paper of a magazine "Microwaves", February 1980, pp. 54-59.

[Problems to be solved by the invention]

In such a push-pull high-frequency amplifier, it is preferable to mount a transistor pair in one case in order to establish balance in the amplifier. However, in actuality, there is an imbalance based on the non-uniformity of the transistor pair and the imbalance of the circuit constituting the amplifier, and therefore, problems such as an increase in combined loss and low-frequency oscillation may occur. is there. This problem is particularly significant in a push-pull amplifying device in which a single transistor is configured as a pair.

Therefore, conventionally, an attempt has been made to improve the stability by inserting an unbalanced absorption circuit composed of RLC between the input terminals 2, 2 'shown in FIG. 6 as shown in FIG. This example is based on the "RF Device Data" published by Motorola.
ata), 1988, AN1035 (pages 7-267 to 7-281).

However, since such an RLC unbalanced absorption circuit has a large L shape as an inductance, the input terminals 2 and
There is a problem that it cannot be applied to a transistor pair having a small dimension between 2 'as it is, and therefore cannot be applied to the above-described high frequency power amplifier.

An object of the present invention is to provide a high-frequency power amplifying device in which instability based on imbalance is improved.

[Means for solving the problem]

The high-frequency power amplifier of the present invention is a high-frequency power amplifier having a pair of high-frequency power elements that receives a high-frequency signal converted into balanced power by a balun converter and amplifies and outputs the high-frequency signal, A configuration in which a pair of high-frequency power elements are mounted on a container, and between the terminals to which the high-frequency signal is input or output, a resistance element having a resistance value greater than the impedance between the terminals is mounted on the container. I do.

In this case, a capacitor may be connected in series with the resistor.

[Action]

ADVANTAGE OF THE INVENTION According to this invention, the instability based on imbalance can be improved by the resistance connected in the container, and application to a small high frequency power amplifier becomes possible.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 (a) is a circuit diagram of a first embodiment of the high frequency power amplifier of the present invention, and FIG. 1 (b) is a plan view of a main part of the circuit of FIG. 1 (a). The same parts as those of the conventional circuit shown in FIG. 6 are denoted by the same reference numerals.

As shown in FIG. 1 (a), in this circuit, by inserting a resistor of resistance value R ₁ between the pair of bipolar transistors Q, Q 'input terminals is connected 2,2' as the amplifier element I have.

That is, as shown in FIG. 1B, the transistor chips 21, 21 'as the transistor pair Q, Q' are mounted on metallized surfaces 20, 20 'provided on an insulating substrate 24, respectively. And these transistor chips 21 and 2
1 'is an input terminal of via a resistor chip 22 as the resistor R _1, the input terminal 2, 2' are connected to the metallized surface 18, 18 'which are bonded thin metal wire 23a, by 23b. The ground terminals of the transistor chips 21, 21 'are connected to the ground metallized surfaces 4, 4' by thin metal wires 23c, 23d. Further, the output terminals 3, 3 'are adhered to metallized surfaces 19, 19', and are connected to the metallized surfaces 20, 20 'by thin metal wires 23e, 23f.

With this configuration, a high frequency amplifying apparatus shown in FIG. 1 (a) and (b), the transistor pair Q performing push-pull operation, between the input terminals of the Q ', a resistor R ₁ in a container constituting the amplifying device The structure is connected. Accordingly, the operation of the push-pull circuit itself is exactly the same as that of the conventional circuit shown in FIG. 6, but the unbalanced component and the instability factor at low frequency caused by the variation of the amplifying device are caused by the resistor chip 22 (the resistor R). ₁ ) will be absorbed. In this case, since the resistance can be configured to be smaller than the inductance L, the amplifying device can be mounted in the container as described above.

It should be noted that if the resistance is zero, no equilibrium operation is performed, so that the resistance must be several times or more larger than the input impedance of the transistor. In the case of a 50 W class transistor in the VHF band, the input impedance is about ₁ to 5Ω, and in that case, the resistance R1 is appropriately about 5 to 100Ω. In the case of the RLC circuit shown in FIG. 7, the resistance was low because a choke coil was inserted for the main purpose of improving the stability at low frequencies. However, in the case of the present invention, it is necessary to set a slightly larger value. There is.

FIG. 2 shows a second embodiment of the present invention. FIG. 2 (a) is a circuit diagram of a main part, and FIG. 2 (b) is a plan view thereof. The same parts as those in FIG. 1 are denoted by the same reference numerals.

In this embodiment, a circuit in which resistors 22 'and 22 "and a capacitor 25 are connected in series is interposed between the input terminals of the transistor chips 21 and 21'. Exactly the same operation, but DC
Since the transistor chips 21 and 21 'are separated by 25, there is an advantage that the DC characteristics of each transistor Q and Q' can be independently performed. This is effective in facilitating the checking of the balance of the device.

In the case of this second embodiment, as shown in FIG. 3 (a) or (b), one of the resistors R ₁ and one capacitor C _1, or two capacitors C _1, and C ₂ One resistor R
It is also possible to configure _one.

FIGS. 4 (a) to 4 (d) show a third embodiment of the present invention, showing different examples in which the present invention is applied to a power amplifier having an internal matching circuit. As shown in these examples, the inductances L _{1 to} L ₄ and the capacitors C ₃ and C _3
A resistor R ₁ and a resistor R ₁ , respectively, between the input terminals 2 and 2 ′ and the base of the transistor pair Q and Q ′ having an internal matching circuit composed of
It may be connected a series circuit of R ₂ and capacitor C _1.

Various modifications of these combinations are also conceivable.

Plan view shown in FIG. 5 is an example of a structure for realizing the equivalent circuit shown in 4 (a), resistor chips 22, capacitor internal matching circuit chip C _3, C ₄ and likewise metallized surface 4 'And connected with a thin metal wire. Other structures are the same as those in FIG. 1 (b).

Here, the above description has been made between the input terminals of the common-emitter bipolar transistor. However, the present invention can be similarly applied to between the output terminals or a common-base or collector-common bipolar transistor. The same applies to the case where a field-effect transistor is used, and the present invention can be applied to a source ground, a gate ground, or a drain ground between input terminals or output terminals. In this case, it is apparent that this can be easily realized by making a small change to the metallized surface, the insulating substrate, or the heat radiating plate or the like.

〔The invention's effect〕

As described above, the present invention receives a high-frequency signal converted to balanced power by a balanced-unbalanced converter, and a pair of high-frequency power elements for power-amplifying and outputting the high-frequency signal are mounted on a container, By connecting a resistive element having a resistance value larger than the impedance between the terminals between the terminals to which a high-frequency signal is input or output, instability based on unbalance can be improved, and this resistance can be reduced. By mounting in a container, there is an effect that it can be applied to a small high-frequency power amplifier having a small dimension between amplification elements.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention. FIG. 1 (a) is a circuit diagram, FIG. 1 (b) is a plan view of a main part, and FIG.
FIG. 3A is a circuit diagram of a main part, and FIG.
FIGS. 3A and 3B are circuit diagrams of main parts of different modifications of the second embodiment of the present invention. FIGS.
FIGS. 5A to 5D are circuit diagrams of different parts of the third embodiment of the present invention, FIG. 5 is a plan view of FIG.
FIG. 6 and FIG. 7 are conventional circuit diagrams. 1. High frequency power amplifier, 2, 2 '... Input terminal, 3, 3'
... output terminals, 4,4 ', 18, 18', 19, 19 '... metallized surface, 5 ... input terminals, 6 ... output terminals, 7 ... power supply terminals, 8, 9 ... balanced unbalanced Converter, 10,10 ', 11,11' ... strip line, 12,13,16,17 ... condenser, 14,15 ...
... Choke coil, 21,21 '... Transistor chip, 2
2,22 ', 22 ″… Resistance chip, 23a-23f …… Metal wire, 2
4 ...... insulating substrate, 25 ...... condenser chip, R _1, R ₂ ...... resistors, C ₁ -C ₄ ...... capacitor (capacitance), L _1, L ₄
…… Inductance, 26 …… Resistance, 27 …… Capacitor,
28 …… Choke coil.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-29003 (JP, A) JP-A-1-117503 (JP, A) JP-A-63-229901 (JP, A) JP-A-57- 193048 (JP, A) JP-A-47-4807 (JP, A) JP-A-63-209309 (JP, A) JP-A-51-112424 (JP, U) JP-A-2-49232 (JP, U) U.S. Pat. No. 4,916,410 (US, A) British Publication 4,455,536 (GB, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H03F 3/60 H01P 5/10 H03H 7/42 WPI

Claims (2)

(57) [Claims] 1. A high-frequency power amplifier having a pair of high-frequency power elements for receiving a high-frequency signal converted into balanced power by a balun converter and power-amplifying and outputting the high-frequency signal. The element is mounted on a container, and a resistance element having a resistance greater than the impedance between the terminals is mounted on the container between terminals to which the high-frequency signal is input or output. Power amplification device. 2. The high-frequency power amplifier according to claim 1, wherein an impedance element in which a resistor and a capacitor are connected in series is connected between said terminals.