JPS6030205A - High frequency amplifier circuit - Google Patents

Abstract

PURPOSE:To prevent a signal from being interrupted even if trouble occurs by using a two-terminal type amplifier circuit and a switch to constitute the flow of the signal in case of the trouble of the amplifier circuit similarly to the function of a one-terminal type amplifier circuit. CONSTITUTION:The signal flows as shown by a broken line and the switch 46 is on when the amplifier circuit 431 is normal. The signal passes through an input terminal 41, the 1st circulator 44, switch 46, and the 2nd circulator 45 and is amplified by the amplifier circuit 431 to flow in the order of the 2nd circulator 45, switch 46, the 1st circulator 44, and an output terminal 42. If trouble occurs to the amplifier circuit 431, the trouble is detected and the switch 46 is turned off; and the signal flows through the input terminal 41, the 1st circulator 44, and switch 46 and is reflected by the switch 46 to flow to the 1st circulator 44 and output terminal 42 in order, so the signal is not interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency amplification circuit that amplifies high frequency signals.

Conventionally, various methods have been adopted for high frequency amplifiers that directly amplify received signals in order to improve the noise figure in the receiving section of a wireless device. Typical examples thereof are shown in FIGS. 1 to 3. Figure 1 shows a circuit that employs a negative resistance amplification circuit. 11 is an input terminal, 12 is an output terminal,
13 is a negative resistance amplifier circuit, and 14 is a circulator for generating and separating input and output signals. If there is a failure in the amplifier circuit 13, the amplification function is lost, but by adopting a circuit configuration that allows the signal to pass through the input/output terminal of the amplifier circuit 130 in the event of a failure, the signal will not be cut off even in the event of a failure. However, the amplifier circuit 13 must have negative resistance, and there is a drawback that sophisticated adjustment work is required to obtain broadband characteristics. FIG. 2 shows an example in which a normal amplifier circuit 231 is used, and this type of amplifier is becoming relatively easy to implement with the development of semiconductor technology. However, if a failure occurs in the amplifier circuit 231, there is a drawback that the signal is cut off, unlike the case shown in FIG.

FIG. 3 shows an example of a configuration in which the signal is not cut off even if there is a failure in the amplifier circuit 231.
, 32, 331 are 21, 22, and 22 in FIG. 2, respectively.
Although it has the same meaning as 231, 34 indicates an input signal branch circuit, 35 indicates a signal synthesis circuit, and 36 indicates a signal bypass path. When a failure occurs in the amplifier circuit 331, the signal flow is transferred to the input terminal 31, the input signal branch i/circuit 34,
Signal bypass path 36, signal synthesis circuit 35, output terminal 32
In order to comply with Jl, the signal flow is not cut off. Therefore, the signal is not cut off, but the signal is attenuated by the loss caused by the input signal branching circuit 34 and the signal combining circuit 35, and the loss generally increases compared to the case of FIG. In order to reduce this loss, it is conceivable to add another amplifier circuit equivalent to the amplifier circuit 331 to the signal bypass path 360, but in this case, it would be more expensive than the one shown in FIG. It had the disadvantage of becoming On the other hand, if a failure occurs in the amplifier circuit 331 and the amplifier circuit 331 needs to be replaced, generally speaking, the amplifier circuit 13 has a one-terminal structure compared to the two terminals of the amplifier circuit 331, so it is easier to replace. The case shown in Figure 1 is superior in that it can be replaced with

The object of the present invention is to use a two-terminal type amplifier circuit and further use a switch to configure the signal flow in the event of a failure to imitate the function of a single-terminal type amplifier circuit. It is an object of the present invention to provide a high frequency amplification circuit configured such that a signal is not cut off even if a failure occurs.

The high frequency amplifier circuit according to the present invention 1C is configured to include a first circulator, a switch, an amplifier circuit, and a second circulator.

In the present invention, the first circulator is for combining an input signal line and an output signal line into one signal line. The switch is for shorting one signal line from the first circulator. The amplifier circuit is for inputting and amplifying the output signal from the switch. The second circulator is for isolating input and output signals of the amplifier circuit and for providing the output of the amplifier circuit to the first circulator via a switch. In the present invention, when the amplifier circuit is normal, the switch is passed through the second circulator, but when the amplifier circuit is abnormal, the input signal is reflected by the switch. The signal is configured to be directly output from the circulator via the output signal line.

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

FIG. 4 is a diagram showing an embodiment of the high frequency amplification circuit according to the present invention. In FIG. 4, 41 is an input terminal, 42 is an output terminal, 431 amplifier circuits, 44 is a first circulator, 45 is a second circulator, 46 is an amplifier circuit 43
This is a switch that prevents the signal from being cut off when a failure occurs in 1. The signal flows as shown in FIG. First circulator 44, switch 46, second circulator 45'ft
The amplified signal is then amplified by the amplifier circuit 431, and the amplified signal flows to the second circulator 45, the switch 46, the first circulator 44, and the output terminal 42, and is output.

In such a circuit configuration, it is theoretically impossible to increase the amplification degree of the amplification circuit 431 without limit), and the amplification degree of the amplification circuit 431 is increased by the isolation of the second circulator 45 (in FIG. If the setting is higher than XdB), there is a possibility of oscillation. Therefore, the amplifier circuit 4
The amplification degree of 31 is below the fixed limit (XdB) of JR,
In order to have a stable circuit configuration, a margin (αd
B')'e It is necessary to increase the effective stability. In this case, increase 11? , the gain of the circuit 431 is (X-α)d
Must be J3 or lower. If there is a fault in the amplifier circuit 431 (in this case, the fault is detected and the switch 46 is turned off)
Due to the short impedance when looking at the switch 46 from the circulator 44 of l, m l, the signal is transmitted to the input terminal 41, the first circulator 44, and the switch 46.
Since the signal is reflected from the switch 46 and flows to the first circulator 44 and the output terminal 42, the signal is not cut off.

As explained above, in the present invention, a two-terminal amplifier circuit is used, and a switch is used to configure the signal flow in the event of a failure to resemble the function of a one-terminal amplifier circuit. Furthermore, there is an effect that a faulty amplifier circuit can be easily and reliably replaced.

[Brief explanation of drawings]

1 to 3 are diagrams showing block configurations of high frequency amplification circuits configured in a conventional manner. FIG. 4 is a diagram showing a block configuration of a high frequency amplification circuit according to the present invention. 11.12, 21, 22, 31, 32. ．． 41,42・
e...terminal 13.231, 331, 431... amplifier circuit 14.
44.45-@ψ Circulator 34... Input signal branch circuit 35... Signal synthesis circuit 36... Bypass circuit 46 O... e switch Fig. 1 Fig. 3 Fig. 2 Sai 4 figure

Claims (1)

[Claims] The first step to make the input signal line and output signal line the 1@ line.
a circulator, a switch for short-circuiting the first signal line from the first circulator, an amplifier circuit for inputting and amplifying the output signal from the switch, and a connection between the input and output signals of the amplifier circuit. and a second circulator for separating the amplifier circuit and supplying the output of the amplifier circuit to the first circulator via the switch, and when the amplifier circuit is normal, the switch connects to the second circulator. (if the amplifier circuit is different, the input signal is reflected by the switch) and output directly from the output signal line via the first circulator. A high frequency amplification circuit characterized by the following configuration.