JPH02190015A - Common amplifier circuit - Google Patents

Abstract

PURPOSE:To improve the reliability and to reduce the deterioration in the characteristic due to a fault of an amplifier by providing distributers branching an input signal into 2<n> ((n) is an integer being two or over), 2<n> sets of amplifiers amplifying independently of each branched signal, and synthesizers synthesizing the 2<n> sets of signals from the amplifiers in in-phase. CONSTITUTION:A signal inputted to an input terminal 11 is branched into two by a distributer 3A, branched respectively into two at distributers 3B, 3C and the branched signals are amplified respectively independently by four amplifiers 1A-1D. The signal from the amplifiers 1A, 1B is synthesized and the signal from synthesizers 4A, 4B is synthesized in in-phase by synthesizers 4B, 4C respectively and the resulting signal is outputted as one signal from an output terminal 12. If one of the four amplifiers 1A-1D is faulty, the other three amplifiers are used for the amplification. Thus, attended with the increase in the number of the amplifiers, the lead of each amplifier is relieved and the deterioration in the gain in the event of a fault of one amplifier is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit that commonly amplifies a plurality of signals input to receiving devices of a plurality of systems.

[Conventional technology]

Conventionally, this type of common amplifier circuit has a configuration in which two amplifiers are operated in parallel, and if one amplifier fails, the entire receiving system will fail and the transmission system will be disrupted. I try not to have any. That is, as shown in FIG. 5, the input signal input from the input terminal 11 is split into two signals by the divider 3, and each signal is sent to two amplifiers IA.

Amplify independently by IB. The amplified signals are then combined into the same phase by the combiner 4 and outputted from the output terminal 12.

[Problem to be solved by the invention]

In the conventional common amplifier mentioned above, two amplifiers IA, I
If one of the amplifiers in B fails, the other amplifier performs amplification, so the signal can be output continuously and signal interruption in the transmission system can be prevented. However, there are problems in that when one amplifier fails, the noise figure (NF) in the receiver tends to deteriorate accordingly, and the S/N ratio deteriorates due to a decrease in the input level of the receiver.

Incidentally, in the above configuration, the gain decreases by 6 dB.

The deterioration of NF was 3 dB.

An object of the present invention is to provide a common amplifier circuit that can improve reliability of the amplifier circuit and reduce characteristic deterioration due to amplifier failure.

[Means to solve the problem]

The common amplifier circuit of the present invention has an input signal of 2" (n is 2").
It consists of a divider that branches into (the above integer number), 2fi amplifiers that independently amplify each branched signal, and a combiner that combines the 2n signals from each amplifier in phase. .

Further, each of the 2n amplifiers is provided with a drive current detection circuit for detecting the drive current of the amplifier.

[Effect]

In the above configuration, as the number of amplifiers increases, the load on each amplifier is reduced, and the gain and N
Reduces F deterioration.

Furthermore, the drive current detection circuit makes it possible to discover failures in each amplifier early or before they occur, thereby reducing the instantaneous interruption rate of the transmission system.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block circuit diagram of one embodiment of the present invention. In the figure, the signal input to the input terminal 11 is transmitted to the distributor 3
The signal is branched into two at A, and each signal is further branched into two at distributors 3B and 3C, resulting in four branches. Then, each branched signal is transmitted through four amplifiers IA to I.
They are each independently amplified by D.

Among the amplified signals, the signals from amplifiers IA and IB are combined by a combiner 4A, and the signals from amplifiers IC and LD are combined in phase by a combiner 4B. Furthermore, each synthesizer 4A, 4
The B signals are combined in phase by the combiner 4C and outputted from the output terminal 12 as one signal.

It goes without saying that each of the amplifiers IA to ID is independent and therefore can be replaced independently.

According to this configuration, if one of the four amplifiers IA to ID fails, the other three amplifiers perform amplification.
Gain and NF damage due to failures are reduced.

Specifically, in the configuration of the present invention, the decrease in the gain of the common amplifier when one of the 2n amplifiers fails can be expressed by the following equation.

G=201og (N/(N-1)) ・”(1)
Here, G is the amount of decrease in gain of the common amplifier circuit when one of the 2n amplifiers fails. N is the number of amplifiers (N=
2n L n is the number of branching stages and is an integer of 2 or more.

When this equation (1) is expressed in a graph, it becomes as shown in Fig. 2.

On the other hand, the deterioration of the NF of the common amplifier circuit when one of the 2n amplifiers fails can be expressed by the following equation.

F-101og [N/(N-1)) ... (2
) Here, F is the amount of deterioration in the NF of the common amplifier circuit when one of the 2n amplifiers fails.

When this equation (2) is expressed in a graph, it becomes as shown in FIG.

Therefore, in the configuration shown in Figure 1, N is 4, and if one unit fails, the gain will decrease by 2.5 dB and the NF deterioration will be 1°2 dB from equations (1) and (2) above. ,
It can be seen that the deterioration of characteristics is reduced compared to the conventional method, and the reliability of the transmission system can be improved.

FIG. 4 is a block circuit diagram of another embodiment of the present invention,
The same parts as in FIG. 1 are given the same reference numerals.

In this embodiment, drive current detection circuits 28 to 2D for detecting drive currents are added to each of the amplifiers IA to ID, respectively.

It goes without saying that with this configuration, as in the first embodiment, deterioration of characteristics due to amplifier failure can be reduced. In addition, during periodic maintenance, it is possible to discover failures in each of the amplifiers IA to ID at an early stage, and it is possible to immediately take measures such as replacing the failed amplifiers. This makes it possible to reduce the S/N deterioration in the receiver and to realize its recovery quickly, thereby reducing the instantaneous interruption rate of the transmission system.

Note that the number of amplifiers is not limited to four, but may be eight or more, that is, n may be three or more, and by increasing n, the deterioration of characteristics can be further effectively reduced.

〔Effect of the invention〕

As explained above, in the present invention, each branched signal is
Because n amplifiers amplify independently, the load on each amplifier is reduced as the number of amplifiers increases, and the gain and NF in the receiver transmission system are reduced even when one amplifier fails. It has the effect of reducing deterioration.

In addition, since each of the 2n amplifiers is provided with a drive current detection circuit that detects the drive current of the amplifier, it is possible to detect failures in each amplifier early or before they occur.
It also has the effect of reducing the momentary interruption rate of the transmission system.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the correlation between the number of branch stages and the amount of gain deterioration, FIG. 3 is a diagram showing the correlation between the number of branch stages and the amount of NF deterioration, and FIG. FIG. 4 is a block circuit diagram of another embodiment of the present invention, and FIG. 5 is a block circuit diagram of a conventional common amplifier circuit. IA~ID...Amplifier, 2A~2D...Drive current detection circuit, 3.3A~3C...Distributor, 4,4A~4C
...Synthesizer, 11...Input terminal, 12...Output terminal. Figure 4 Figure 5

Claims (1)

[Claims] 1. A distributor that branches an input signal into 2^n (n is an integer of 2 or more), and 2^n amplifiers that independently amplify each branched signal. A common amplifier circuit comprising: a synthesizer for in-phase synthesizing 2^n signals from each amplifier. 2. The common amplifier circuit according to claim 1, wherein each of the 2,2^n amplifiers is provided with a drive current detection circuit for detecting the drive current of the amplifier.