JPH04104604A - High frequency amplifier - Google Patents

Abstract

PURPOSE:To make the circuit scale small and to simplify the circuit by providing a power distributor distributing an input signal into two systems, 1st and 2nd amplifiers amplifying each of the distributed signals and a power synthesizer synthesizing output signals of each amplifier and outputting the synthesized output signal to an external device to the high frequency amplifier. CONSTITUTION:The amplifier is provided with a power distributor 101 distributing an input signal Sin to two systems in phase, 1st and 2nd amplifiers 102, 103 amplifying each of the signals distributed into two systems by the power distributor 101 and a power synthesizer 104 synthesizing output signals of the 1st and 2nd amplifiers 102, 103 and outputting the synthesized signal. Moreover, a transmission line 107 through which a reflecting wave by an internal reactance of the 1st and 2nd amplifiers 102, 103 is cancelled is provided between output lines of the 1st and 2nd amplifiers 102, 103. Thus, the high frequency amplifier is realized, in which the circuit scale is made small and simplified entirely.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 6 and 7) Means and action for solving the problem to be solved by the invention (Figure 1) Examples (a) First embodiment (b) Second embodiment (3) Third embodiment (4) Other embodiments Effects of the invention (Fig. 2, Fig. 3) (Fig. 4) (Fig. 5) (Figure 1) [Summary] A power divider that divides the input signal into two systems, first and second amplifiers that amplify each divided signal, and a power combiner that combines and outputs the output signals of each amplifier. The purpose of the present invention is to provide a high frequency amplifier that can be made small and simple in circuit scale, and to provide a high frequency amplifier that can cancel reflected waves due to the internal reactance of the amplifier section and achieve matching. , a power divider that distributes the input signal into two systems in phase, first and second amplifiers that amplify the first and second signals distributed to the two systems by the power divider, and the first and second amplifiers. a power combiner for combining output signals of the amplifiers; A transmission line is provided between the input-side lines or between the output-side lines of the second amplifier, and cancels reflected waves due to internal reactance of the amplifier.

[Industrial Application Field] The present invention relates to a high-frequency amplifier that performs power amplification of a high-frequency signal, and particularly relates to a power divider that distributes an input signal into two systems;
The present invention relates to a high frequency amplifier that includes first and second amplifiers that amplify each distributed signal, and a power combiner that combines and outputs the output signals of the respective amplifiers.

In recent years, high-frequency amplifiers used in mobile communications and satellite communications are required to be highly efficient, and have been actively researched. Since a harmonic processing circuit or the like is connected to the output of such a high frequency amplifier, it is necessary to simplify the matching circuit so as not to increase the overall circuit scale of the high frequency amplifier.
It is desired that the device be made smaller.

[Prior Art] As a high-frequency amplifier that performs power amplification of a high-frequency signal, there is a package-type FET amplifier as shown in FIG.

In this FET amplifier, an input signal is branched into two by two bonding wires 1 and 2, passed through matching circuits 3 and 4, and input to amplifiers 5 and 6 made of FET chips, where they are amplified. The amplified output signals of the amplifiers 5 and 6 operating in parallel are combined by a combining circuit 7 on a microstrip line board disposed on the output side, and then impedance matched by a matching circuit 8 and output. In addition, in Figure 6,
Although two amplifiers are used, they do not interact with each other in any way; their outputs are simply combined.

Another example of a high frequency amplifier is a high frequency amplification circuit filed by the applicant on April 28, 1989 (Japanese Patent Application No. 01-107375, titled "High Frequency Amplification Circuit").

FIG. 7 is a block diagram of such a high-frequency amplification circuit, in which a power divider 1 divides the input signal Sin into two systems with mutually opposite phases.
1, and the first and second signals Sa distributed by the power divider 11.

First and second amplifiers 1 consisting of FETs etc. that amplify sb
2.13, a coupling circuit 14 that transmits a part of the output signal of the first and second amplifiers 12.13 from one side to the other and cancels the reflected waves, and the first and second amplifiers whose reflected waves are canceled. It is equipped with a power combiner 15 that combines and outputs the output signals of. Although not shown, the coupling circuit 14 is constituted by capacitance or inductance, and equivalently cancels out the reflected waves to achieve matching.

[Problems to be Solved by the Invention] In the high-frequency amplifier shown in FIG. 6, the matching circuit 8 is a stub or a thin film capacitor connected in parallel, so in order to achieve sufficient matching, the area of the matching circuit must be increased. There's a problem.

Furthermore, in the high frequency amplifier shown in FIG. 7, which does not require a stub, power must be distributed and combined in opposite phases in the power divider 11 and power combiner 15, requiring a rat race circuit, etc. There is a problem that capacitance and inductance elements are required, which increases the size of the circuit. In addition, if chip components are used for the capacitance and inductance of the coupling circuit 14 in order to make the circuit smaller, the lines connected to the amplifier must be placed closer together, which causes coupling between the lines themselves and makes it difficult to design the coupling circuit. The problem arises that it is not easy.

From the above, an object of the present invention is to provide a high frequency amplifier whose overall circuit size can be made small and simple.

Another object of the present invention is to provide a high frequency amplifier that can achieve matching by canceling reflected waves due to the internal reactance of an amplifying section such as an FET.

Still another object of the present invention is to provide a high frequency amplifier that can achieve matching by canceling out reflected waves caused by discontinuity between the internal resistance of an amplifier section such as an FET and the load resistance.

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

101 is a power divider that divides the input signal Sin into two systems in phase; 102 and 103 are first and second amplifiers that amplify each signal distributed to the two systems by the power divider; 104;
105 and 106 are power combiners that combine and output the output signals of the first and second amplifiers; Transmission line 107, which is provided between the second amplifier and the power combiner and converts the internal resistance of each amplifier to match the output resistance (load resistance).
is a transmission line that is provided between the output lines of the first and second amplifiers and cancels reflected waves due to the internal reactance of the amplifiers.

[Function] When the transmission lines 105 and 106 are not considered, the first or second
The load admittance when looking at the output side from the amplifiers 102 and 103 is as follows. However, Y and θ are the characteristic admittance and electrical length of the transmission line 107.

Therefore, if the internal admittance of the amplifier is 00+jB, then if the electrical length θ of the transmission line 107 is determined as follows, a part of the output signal of each amplifier is transmitted to the other, and it depends on the internal susceptance B0 of each amplifier. In other words, reflected waves due to internal reactance can be canceled out.

However, in the transmission line 107, the reflected waves that occur because the internal resistance of the amplifier is discontinuous with the load resistance cannot be canceled. Therefore, transmission lines 105 and 106 are provided to convert the internal resistance into impedance so that Go=G/2, thereby achieving matching and eliminating reflected waves.

According to the present invention, since in-phase signals are distributed and combined, signal distribution and signal synthesis can be performed with a simple configuration, such as branching and combining using bonding wires.
Furthermore, by simply providing a simple element such as a transmission line, it is possible to eliminate reflected waves caused by the internal reactance of the amplifier and reflected waves caused by the fact that the internal resistance of the amplifier is not equal to the load resistance.

[Embodiments] (a) First Embodiment FIG. 2 is a block diagram of a power divider which is an embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

Reference numeral 101 denotes a power divider that distributes the input signal Sin into two systems in the same phase.
01b, the input signal line 101c is branched into two systems. 102 and 103 are first, amplifying signals Sa and Sb distributed into two systems by the power divider;
This is a second amplifier, and although not shown in detail, it is composed of FETs and the like. 104 is a power combiner that combines and outputs the output signals S a' and S b' of the first and second amplifiers. This power combiner 104 has a configuration in which signals Sa and Sb' are guided to an output line 104c by bonding wires 104a and 104b and are combined.

Reference numerals 105 and 106 are transmission lines (a type of impedance converter) that are provided between the first and second amplifiers 102, 103 and the power combiner 104, and convert the internal resistance of each amplifier to match the load resistance. As will be described later, the transmission lines 105 and 106 convert the internal resistance of each amplifier to twice the load resistance value R5 (= 2 RL),
It has a predetermined length and a predetermined characteristic impedance.

107 is a transmission line; Second amplifier 102.1
03 between the output side lines, output signals Sa, Sb'
A portion of the signal is transmitted to the other to cancel the reflected waves due to the internal reactances of the first and second amplifiers.

FIG. 3 is an equivalent circuit of the high frequency amplifier of FIG. 2 without considering the transmission lines 105 and 106, and 102a
, 103a is the equivalent current source (I) of the first and second amplifiers 102 and 103, 102b and 103b are the internal conductances (Go) of each amplifier, 102c and 103c are the internal susceptances (B, ) of each amplifier, 104', 104' is an output conductance (load conductance G) when looking at the output from the input side of the power combiner 104, and 107' is an admittance element having a characteristic admittance Y and an electrical length θ, to which the transmission line 107 contributes. .

From this equivalent circuit, the first or second amplifier 102°103
The load admittance seen from the output side is as follows.

That is, as shown in the equivalent circuit, current L1.2 and voltage V1. When V2 is determined, the current I0. I, is the transmission line 7
Using the matrix (characteristic admittance), Ix=Y ((1/jtanθ) ・Vt (1/j
sin θ) v2)...(1) Iz=Y ((1/j sin θ) ・V, +(1/ j
tanθ)v2)...(2) Can be expressed. Furthermore, the following equation (3) holds true due to the continuity of the current at both ends of the transmission line. When calculating V and v2 from equations (3) and (4), we get V, = (IL)/ (G+00+jB,) (
5) V2= (Eng L)/(G+00+jBa)
(6) becomes. Substituting equations (5) and (6) into equation (1), 11=Y・(I (sinθ−tanθ) −
I□sinθ+I, tanθ)/ (G+G, +jB0
) ・jtanθsinθ. Therefore, ((G"Go+J Bo)",)tanθsinθ
/Y+sinθ)■, -I2tanθ= 工(sinθ
−tanθ)・−+(7). Similarly, in equation (2), (
5), Substituting equation (6), l2=Y・(I (
sinθ−tanθ)+I, tanθ−I2sinθ)
/ (G×G0+jB,) ・jtanθsinθ. Therefore, -11tanθ+((G+G0+jB,) ・jta
nθ sin θ/Y + sin θ) It = I
(sin θ−tan θ) (8). Here, for simplicity, α■□-βI2=γ...(7)'-βI0+αI
2=γ...(8)′, then, I,=I2 From (5) and (6), V1=V2 Therefore, from equations (1) and (2), I, / V, = Y ((1/ j tanθ)
(1/j sin θ)), so the admittance looking to the right from A-A' is.

Therefore, if the internal admittance of the amplifier is 00+jB0, and the electrical length θ of the transmission line 107 is determined as be able to.

From the above, the transmission line 107 can cancel the reflected waves due to internal susceptance (internal reactance), but the transmission line 107 cannot cancel the reflected waves that occur because the internal resistance of the amplifier is discontinuous with the load resistance. Can not.

Therefore, in the present invention, transmission lines 105 and 106 are provided to ensure matching so that the internal resistance and load resistance do not become discontinuous, thereby eliminating reflected waves.

That is, if the load resistance is RL, the transmission lines 105 and 106 are connected to the first and second amplifiers 102 and 103 so that the internal resistance R0 of the first and second amplifiers 102 and 103 is twice the load resistance RL. Second
It is provided between the amplifiers 102 and 103 and the power combiner 104.

As a result, the combined internal impedance of the two parallel systems is 2
- RL is connected in parallel, and its value becomes RL, which becomes equal to the load resistance value, thereby achieving matching and eliminating the generation of reflected waves due to resistance value discontinuity.

(b) Second Embodiment FIG. 4 is a configuration diagram of a second embodiment according to the present invention, in which the same parts as those in FIG. A power divider divides the signal Sin into two systems in phase, and reference numerals 102 and 103 represent each signal Sa distributed into the two systems by the power divider.

The first and second amplifiers 104 that amplify sb are power combiners that combine and output the output signals Sa' and Sb' of the first and second amplifiers, and a power combiner 104-1,
It has impedance converters 104-2 and 104-3. The power combining unit 104-1 connects the bonding wire 1
04a and 104b connect the two signal lines to the output line 10.
4c, and the impedance converter 10
4-2 and 104-3 are constituted by 1/4λ wavelength impedance conversion lines, the input resistance of which is equal to the load resistance RL.

105' and 106' are the first and second amplifiers 102°10
3 and the power combiner 104, is a transmission line (a type of impedance converter) that converts the internal resistance of each amplifier to be equal to the load resistance RL, and has a predetermined length and a predetermined characteristic impedance. .

107 is provided between the output side lines of the first and second amplifiers,
This is a transmission line that transmits a portion of the output signals Sa' and Sb' to each other to cancel reflected waves due to the internal reactances of the first and second amplifiers.

According to this high frequency amplifier, the internal resistance of each amplifier 102 and 103 is reduced by the load resistance R through the transmission lines 105' and 106'.
Since the conversion is made equal to L (=50Ω), the transmission line 105 can be used even in amplifiers with arbitrary internal impedance.
There is an advantage that the lengths of ' and 106' can be easily calculated.

In other words, since various measurements (measurement of amplifier internal resistance, internal susceptance, etc.) are performed based on RL (=500), the length of the transmission line can be easily determined using the measurement results as they are. Advantages 6 Furthermore, even if the difference between the internal resistance and the load resistance is large, there is no need to make the 1/4λ wavelength line thicker, and there is an advantage that it is easy to manufacture.

(c) Configuration diagram of third embodiment FIG. 5 is a configuration diagram of a third embodiment according to the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals. 1 is a power divider that divides the input signal Sin into two systems in phase, and 102 and 103 are respective signals Sa that are distributed to the two systems by the power divider.

The first and second amplifiers 104 that amplify sb are power combiners that combine and output the output signals Sa' and Sb' of the first and second amplifiers, and the power combiner 104-1'
and impedance converter 104-2'104-3'
have. The power combining section 104-1' has a configuration in which two signal lines are connected to an output line 104c by bonding wires 104a and 104b, and impedance converters 1o4-2' and 104-3' are 1/4λ wavelength impedance conversion lines. The internal resistance of each amplifier is converted to twice the load resistance RL (=2·RL) for matching. In addition, the impedance converter 104-2'
104-3' corresponds to transmission lines 105 and 106 in FIG.

107 is the first. Provided between the output side lines of the second amplifier,
This is a transmission line that transmits a portion of the output signals Sa' and Sb' to each other to cancel reflected waves due to the internal reactances of the first and second amplifiers.

This high-frequency amplifier has fewer parts than the high-frequency amplifier shown in FIG. 6, and can be made smaller and simpler. Note that if the difference between the internal resistance and the load resistance is too large, the 1/4λ wavelength line, which is an impedance converter, becomes thick.

(d) Other Embodiments In the above description, the transmission line 107 is provided between the output lines of the first and second amplifiers, but it may also be provided between the input lines of the first and second amplifiers.

In other words, even if the transmission line 107 is provided between the input lines of the first and second amplifiers, the equivalent circuit shown in FIG.
．． A portion of the input signal of the second amplifier can be transmitted from one to the other to cancel the reflected waves.

Although the present invention has been described above with reference to examples, the present invention can be modified in various ways according to the gist of the present invention as described in the claims, and the present invention does not exclude these modifications.

[Effects of the Invention] According to the present invention, the first and second signals are distributed in the same phase, and part of the input signal or output signal of the first and second amplifiers is transmitted to the other via the transmission line. Since the configuration is configured such that the reflected waves due to the internal reactance of each amplifier are canceled out, and the outputs of the first and second amplifiers are combined in the same phase, it is possible to provide a high frequency amplifier without reflected waves, and also to cancel the reflected waves due to the internal reactance of each amplifier. There is no need for a rat race circuit, and the structure can be made smaller and simpler.

Further, according to the present invention, since the internal resistance of the amplifier and the load resistance are matched with the impedance converter made of the transmission line, reflected waves due to discontinuity between the internal resistance and the load resistance can be easily suppressed. Can be canceled out.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a configuration diagram of a first embodiment of the present invention, FIG. 3 is an equivalent circuit diagram of a high frequency amplifier according to the present invention, and FIG. 4 is a diagram illustrating the second embodiment of the present invention. FIG. 5 is a configuration diagram of a third embodiment of the present invention, FIG. 6 is a first configuration diagram of a conventional Takaoka amplifier, and FIG. 7 is a second configuration diagram of a conventional Takaoka amplifier. It is. 101 ・ 102゜104 ・ 105゜107 ・

Claims (2)

[Claims] (1) Power divider that distributes the input signal into two systems in phase (
101), first and second amplifiers (102, 103) that amplify the first and second signals distributed to two systems by the power divider, and synthesize the output signals of the first and second amplifiers. Power combiner (1
04), and a transmission line (107) provided between the input side lines or between the output side lines of the first and second amplifiers to cancel reflected waves due to internal reactance of the amplifiers. (2) A claim characterized in that the transmission line (105, 106) is provided between the first and second amplifiers and the power combiner, respectively, and converts the internal resistance of each amplifier to match the load resistance. The high frequency amplifier according to item 1.