Amplification device

Abstract

To suppress the generation of an excessive output of an amplification device, and increase a period where an output level of the amplification device is continuously changed.SOLUTION: An amplification device 1 includes: a variable attenuator 110 that reduces a signal strength of an input signal, and outputs it as a decay signal; an amplifier 120; a coupler 130 that divides an amplification signal into an output signal and a detected signal; a detection circuit 140 that detects the signal strength of the detected signal; a CPU 152 that determines a first decay amount of the variable attenuator 110 in accordance with the signal strength of the detected signal, and outputs a control value corresponding to the first decay amount; a DA converter 153 that convers the control value to a first analog signal; an analog APC circuit 154 that outputs a second analog signal corresponding to a second decay amount corresponding to the signal strength of the detected signal; and a switch part 155 that switches between a state where the first analog signal is input into the variable attenuator 110 and a state where the second analog signal is input into the variable attenuator 110 on the basis of the control of the CPU 152.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an amplification device.

Background Art

[0002] There is known an amplification device having an APC (Automatic Power Control) circuit that detects the signal intensity of the signal output from an amplifier and controls the signal output so as to have a predetermined signal intensity according to the detection result (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the output power of an amplification device is controlled by analog APC using a LOG-AMP, over-output may occur before the output power converges. Therefore, since it is necessary to provide an attenuator on the output side of the amplification device so that the subsequent device is not adversely affected even in an over-output state, the range in which the APC operation is possible is reduced. Thus, it is conceivable to use digital APC that controls the output power by a processor so as not to generate an over-output state, but in digital APC, there arises a problem that the output level does not change continuously.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to suppress the occurrence of over-output of an amplification device and to lengthen the period during which the output level of the amplification device changes continuously.

Means for Solving the Problem

[0006] The amplification device of the present invention is an amplification device that amplifies an input input signal and outputs it as an output signal, and includes a variable attenuator that attenuates the signal strength of the input signal and outputs it as an attenuation signal, an amplifier that amplifies the attenuation signal and outputs it as an amplified signal, a splitting circuit that splits the amplified signal into a detected signal for detecting the signal strengths of the output signal and the amplified signal, a detection circuit that detects the signal strength of the detected signal split by the splitting circuit, a processor that determines a first attenuation amount of the variable attenuator according to the signal strength of the detected signal and outputs a control value corresponding to the first attenuation amount, a DA converter that converts the control value into a first analog signal, an analog APC circuit that outputs a second analog signal corresponding to a second attenuation amount according to the signal strength of the detected signal, and a switching unit that switches between a state in which the first analog signal is input to the variable attenuator and a state in which the second analog signal is input to the variable attenuator based on the control of the processor.

[0007] The processor may control the switching unit such that the first analog signal is input to the variable attenuator when the signal strength of the detected signal is less than a first predetermined value, and the second analog signal is input to the variable attenuator when the signal strength of the detected signal is greater than or equal to the first predetermined value.

[0008] The processor may control the switching unit such that the first analog signal is input to the variable attenuator until a predetermined time has elapsed after detecting that the signal strength of the detected signal is greater than or equal to a second predetermined value that is smaller than the first predetermined value, and the second analog signal is input to the variable attenuator after the predetermined time has elapsed.

Advantages of the Invention

[0009] According to the present invention, the occurrence of over-output of the amplification device can be suppressed, and the effect that the period during which the output level of the amplification device continuously changes becomes longer is achieved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] [Configuration of Amplifier 1] FIG. 1 is a diagram showing a configuration example of the amplifier 1 of this embodiment. The amplifier 1 amplifies an input input signal and outputs it as an output signal. The amplifier 1 outputs an output signal obtained by amplifying the input signal to a predetermined signal intensity by an APC circuit. The amplifier 1 includes an input terminal 10, an output terminal 20, a variable attenuator 110, an amplifier 120, a coupler 130, a detection circuit 140, and an output adjustment circuit 150.

[0012] An input signal is input to the input terminal 10, and an output signal is output from the output terminal 20. The variable attenuator 110 attenuates the input signal and outputs it to the amplifier 120 as an attenuated signal. The variable attenuator 110 outputs an attenuated signal obtained by attenuating the input signal by an attenuation amount corresponding to a control signal input from the output adjustment circuit 150.

[0013] The amplifier 120 amplifies the attenuated signal output by the variable attenuator 110. The amplifier 120 outputs a signal obtained by amplifying the attenuated signal at a predetermined amplification rate as an amplified signal.

[0014] The coupler 130 is a splitting circuit that splits the amplified signal output by the amplifier 120 into an output signal output from the output terminal 20 and a detected signal for detecting the signal intensity of the amplified signal. The coupler 130 supplies a part of the amplified signal to the detection circuit 140 as a detected signal, and outputs the remainder of the amplified signal from the output terminal 20 as an output signal.

[0015] The detection circuit 140 detects the signal strength of the detected signal input from the coupler 130. The detection circuit 140 inputs a signal indicating the signal strength of the detected signal (hereinafter referred to as the "signal strength signal") to the output adjustment circuit 150.

[0016] The output adjustment circuit 150 determines the attenuation amount of the variable attenuator 110 based on the signal strength of the detected signal detected by the detection circuit 140. For example, the output adjustment circuit 150 determines the attenuation amount of the variable attenuator 110 so that the signal strength of the detected signal becomes a predetermined value.

[0017] Here, as an example, it is assumed that the coupler 130 divides the amplified signal so that the power ratio between the output signal and the detected signal is 10:1, and the output adjustment circuit 150 controls the signal strength of the output signal to be +10 dBm. In this way, when the output signal is +10 dBm (10 mW), the detected signal becomes 0 dBm (1 mW). Therefore, the output adjustment circuit 150 does not change the attenuation amount of the variable attenuator 110 when the signal strength of the detected signal is 0 dBm.

[0018] When the signal strength of the detected signal is +1 dBm (1.26 mW), since the output signal becomes +11 dBm (12.6 mW), the output adjustment circuit 150 increases the attenuation amount of the variable attenuator 110 by 1 dB. For example, the output adjustment circuit 150 supplies a control signal for further attenuating by 1 dB from the current attenuation amount to the variable attenuator 110.

[0019] [Configuration of Output Adjustment Circuit 150] The output adjustment circuit 150 includes an AD converter 151, a CPU 152, a DA converter 153, an analog APC circuit 154, and a switching unit 155. The signal strength signal output by the detection circuit 140 is input to the AD converter 151 and the CPU 152.

[0020] The output adjustment circuit 150 has a digital APC and an analog APC. The AD converter 151, the CPU 152, and the DA converter 153 constitute the digital APC, and the analog APC circuit 154 constitutes the analog APC. In the output adjustment circuit 150, immediately after starting the operation of adjusting the level of the output signal, the attenuation amount of the variable attenuator 110 is controlled by the digital APC, and after the level of the output signal reaches a predetermined value, the attenuation amount of the variable attenuator 110 is controlled by the analog APC.

[0021] The AD converter 151 converts the voltage of the signal strength signal input from the detection circuit 140 into a digital value. The AD converter 151 inputs the converted digital value to the CPU 152.

[0022] The CPU 152 is, for example, a CPU (Central Processing Unit). The CPU 152 is a processor that determines the first attenuation amount of the variable attenuator according to the signal strength of the detected signal and outputs a control value corresponding to the first attenuation amount. The CPU 152 inputs the control value corresponding to the first attenuation amount to the DA converter 153.

[0023] The CPU 152 determines the first attenuation amount of the variable attenuator 110 based on the digital value input from the AD converter 151 by executing a program stored in the built-in memory. The first attenuation amount is the attenuation amount of the variable attenuator 110 determined by the CPU 152. The CPU 152 determines the attenuation amount, for example, by referring to a data table showing the relationship between the digital value corresponding to the signal strength signal and the first attenuation amount.

[0024] The DA converter 153 converts the control value input from the CPU 152 into a first analog signal. The DA converter 153 inputs the first analog signal to the switching unit 155.

[0025] The analog APC circuit 154 outputs a second analog signal corresponding to a second attenuation amount according to the signal strength of the detected signal. The analog APC circuit 154 generates a second analog signal corresponding to a second attenuation amount according to the level of the signal strength signal without converting the signal strength signal input from the detection circuit 140 into a digital value. The analog APC circuit 154 is composed of analog elements such as, for example, an operational amplifier, a transistor, a resistor, or a capacitor.

[0026] The switching unit 155 is a switch that switches between a state in which the first analog signal is input to the variable attenuator 110 and a state in which the second analog signal is input to the variable attenuator 110 based on the control of the CPU 152. The switching unit 155 is, for example, an analog switch, but may be composed of a transistor.

[0027] [Switching control of the switching unit 155] Hereinafter, the switching control of the switching unit 155 by the CPU 152 will be described in detail. When the signal strength of the detected signal is less than a first predetermined value, the CPU 152 controls the switching unit 155 so that the first analog signal is input to the variable attenuator 110, and when the signal strength of the detected signal is greater than or equal to the first predetermined value, the second analog signal is input to the variable attenuator 110. For example, when the signal strength of the detected signal is less than the first predetermined value, the CPU 152 inputs a control signal with a first level voltage to the switching unit 155, and when the signal strength of the detected signal is greater than or equal to the first predetermined value, the CPU 152 inputs a control signal with a second level voltage to the switching unit 155.

[0028] The first predetermined value is, for example, a value set in advance by the user of the amplification device 1 as a value indicating the target level of the output signal. The switching unit 155 stores, for example, the first predetermined value input from an external device (for example, a computer) in an internal memory, and controls the switching unit 155 by reading out the stored first predetermined value.

[0029] When the CPU 152 operates in this manner, when the signal strength of the detected signal is less than the first predetermined value, the output adjustment circuit 150 operates as a digital APC, so that an excessive signal can be prevented from being output from the output terminal 20. Then, after the signal strength of the detected signal reaches the first predetermined value, the output adjustment circuit 150 operates as an analog APC, so that the output signal can be made to change continuously. As a result, the occurrence of over-output of the amplification device 1 is suppressed, and the period during which the output level of the amplification device 1 changes continuously becomes longer.

[0030] The CPU 152 may switch the switching unit 155 so that the first analog signal is input to the variable attenuator 110 in response to the signal strength of the detected signal falling below a predetermined value that is lower than the first predetermined value. When the CPU 152 operates in this manner, when the input signal becomes small and the output signal does not need to change continuously, it is possible to prevent an excessive signal from being output from the output terminal 20 in subsequent operations.

[0031] Incidentally, there may be a case where the time from the initial value of the input signal to reaching the first predetermined value is substantially constant. In such a case, the CPU 152 detects that the signal strength of the detected signal is equal to or greater than a second predetermined value that is smaller than the first predetermined value, and the first analog signal is input to the variable attenuator 110 until a predetermined time elapses, and after the predetermined time has elapsed, the second analog signal is input to the variable attenuator 110. The switching unit 155 may be controlled so that it is input.

[0032] The second predetermined value is, for example, the minimum value assumed as the level of the input signal. The predetermined time is the time required for the input signal to reach the first predetermined value from the second predetermined value. In order to surely prevent an excessive signal from being output from the output terminal 20, the predetermined time may be a time slightly longer than the time required for the input signal to reach the first predetermined value from the second predetermined value.

[0033] Even when the CPU 152 operates in this manner, when the signal strength of the detected signal is less than approximately the first predetermined value, the output adjustment circuit 150 operates as a digital APC, preventing an excessive signal from being output from the output terminal 20. After the signal strength of the detected signal reaches approximately the first predetermined value, the output adjustment circuit 150 operates as an analog APC, so that the output signal changes continuously.

[0034] [Operation Example of Amplifier Device 1] FIG. 2 is a diagram showing an operation example of the amplifier device 1. FIG. 2 shows a signal output from the amplifier device 1 (amplifier device output), a control signal input from the CPU 152 to the switching unit 155, and a signal input from the switching unit 155 to the variable attenuator 110 (switching unit output). The horizontal axis in FIG. 2 represents time.

[0035] Until the signal output from the output terminal 20 reaches a specified level corresponding to a state where the signal strength of the detected signal is the first predetermined value, the control signal is at a low level (corresponding to the first level), and the output adjustment circuit 150 operates as a digital APC. After that, when the signal output from the output terminal 20 reaches the specified level, the control signal becomes a high level (corresponding to the second level), and the output adjustment circuit 150 operates as an analog APC. With the output adjustment circuit 150 configured in this way, the signal output from the amplifier device 1 does not exceed the specified level, and after the signal output from the amplifier device 1 reaches the specified level, the time during which the signal output from the amplifier device 1 changes continuously becomes longer.

[0036] As described above, the present invention has been described using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist. For example, all or part of the device can be functionally or physically distributed and integrated in any unit. Also, new embodiments resulting from any combination of a plurality of embodiments are included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination have the effects of the original embodiments combined.

Description of Reference Numerals

[0037] 1 Amplifier 10 Input terminal 20 Output terminal 110 Variable attenuator 120 Amplifier 130 Coupler 140 Detection circuit 150 Output adjustment circuit 151 AD converter 152 CPU 153 DA converter 154 Analog APC circuit 155 Switching section

Claims

1. An amplification device that amplifies an input input signal and outputs it as an output signal, a variable attenuator that attenuates the signal strength of the input signal and outputs it as an attenuation signal, an amplifier that amplifies the attenuation signal and outputs it as an amplified signal, a splitting circuit that splits the amplified signal into a detected signal for detecting the signal strengths of the output signal and the amplified signal, a detection circuit that detects the signal strength of the detected signal split by the splitting circuit, a processor that determines a first attenuation amount of the variable attenuator according to the signal strength of the detected signal and outputs a control value corresponding to the first attenuation amount, a DA converter that converts the control value into a first analog signal, an analog APC circuit that outputs a second analog signal corresponding to a second attenuation amount according to the signal strength of the detected signal, a switching unit that switches between a state in which the first analog signal is input to the variable attenuator and a state in which the second analog signal is input to the variable attenuator based on the control of the processor, An amplification device having the above.

2. The processor controls the switching unit such that the first analog signal is input to the variable attenuator when the signal strength of the detected signal is less than a first predetermined value, and the second analog signal is input to the variable attenuator when the signal strength of the detected signal is greater than or equal to the first predetermined value. The amplification device according to Claim 1.

3. The processor controls the switching unit such that the first analog signal is input to the variable attenuator until a predetermined time has elapsed after detecting that the signal strength of the detected signal is greater than or equal to a second predetermined value that is smaller than the first predetermined value, and the second analog signal is input to the variable attenuator after the predetermined time has elapsed. The amplification device according to Claim 1.

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