JPH10247828A - Limiter amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a limiter amplifier with a wide dynamic range and a good transient response. SOLUTION: A detection diode 6, whose detection current changes with an amplitude of a received signal, is integrated in a gate bias circuit of a transistor(TR) 1 as a current source for generating a feedback voltage to bias a gate by a voltage, which is calculated as a product of the resistance of a breeder resistor 5 and a detected current in a negative voltage direction. The gate is biased in the negative voltage direction to decrease a gate current IG of the TR 1, thereby reducing the undesirable effects called migration regarding reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a limiter amplifier capable of limiting a signal transmission amplitude to a constant output value.

[0002]

2. Description of the Related Art As an application of a limiter amplifier, a communication device in which the amplitude of a signal changes with time or an amplitude limiting circuit for maintaining a constant output level of a signal circuit can be considered. A which has been used instead of the limiter amplifier
In an automatic output control circuit called LC, it was difficult to follow a sharp signal change due to the problem of the loop response time of the closed loop control. Therefore, a limiter that can directly limit the magnitude of the signal amplitude at a high speed by the signal transmission speed itself becomes effective.

In particular, a communication device for performing microwave transmission requires a limiter that responds to a frequency in a microwave band, and a control by a closed loop control circuit cannot satisfy a sufficiently high speed response. In addition, the limiter amplifier described here has an input range that can limit the magnitude of the amplitude, that is, a dynamic range, in comparison with a diode limiter that does not have an amplification function, in combination with a function of compensating for a passage loss when configuring a circuit. There was an advantage that could be increased.

FIG. 9 shows a conventional limiter amplifier.
1 is a transistor having an amplifying function, 2a and 2b are matching circuits of the transistor 1, and 3a, 3c, 4a and 4d are first and third choke coils and first and fourth choke coils for suppressing leakage of a transmission signal to a bias circuit. , A bleeder resistor provided as a path through which the gate current of the transistor 1 flows, 7, 8 first and second power supplies for supplying a voltage to the gate and drain of the transistor 1, and 12 a transistor This is a self-bias feedback resistor that performs feedback for one gate current. The conventional limiter amplifier shown in FIG. 9 amplifies the amplitude of the signal input to the input terminal by the transistor 1 and simultaneously
Can limit the signal amplitude to the maximum output amplitude determined by the second power supply 8 and output the signal.

When the transistor 1 is of an N-channel gate type, the resistor 12 for self-bias feedback applies feedback to the forward gate current IG flowing through the gate terminal of the transistor 1 during the saturation operation of the limiter amplifier to suppress it. Improve the withstand input power level of the transistor 1 as reported in the IEICE General Conference, 1979, Lecture Number 756, "X-Band Low Noise GaAs FET Amplifier Withstand Power Test". That is, when the gate current IG flows, a potential opposite to the inflow direction of the IG is generated at both ends of the resistor 12 to suppress the IG. Since the IG has an undesirable effect called migration on the reliability of the transistor 1, it is necessary to suppress it by using the resistor 12, and in that sense, the feedback resistor 12 is very important.

FIG. 10 is a diagram for explaining the transmission characteristics of a limiter amplifier. FIG.
(B) shows a signal input-to-gate current characteristic, (c) shows a signal input-to-gate voltage characteristic, and (d) shows a signal input-to-drain current characteristic. In the range indicated by points A to B in FIG. 10A, the output of the amplifier exhibits limiter characteristics, and at the same time, a forward gate current flows in the limiter portion due to the detection operation of the transistor as shown in FIG. 10B. The forward gate current causes a voltage drop in the self-bias feedback resistor 12 and the bleeder resistor 5, and pulls in the gate terminal voltage in the negative direction as shown in FIG. As a result, the drain current changes as shown in FIG.

[0007] A microwave band limiter amplifier using a general transistor has an ability to keep an output substantially constant in an input range of 5 to 10 dB, but requires a larger dynamic range. In this case, a method of connecting the limiter amplifiers shown in FIG. 9 in multiple stages is used. FIG. 11 shows a conventional limiter amplifier connected in multiple stages in order to expand the dynamic range of the limiter, and 18 shows a functional unit of the limiter amplifier including the bias circuit and the transistor described in FIG. In this case, for example, by connecting five functional units 18 each having a dynamic range of 5 dB in one stage, a dynamic range of at least 25 dB can be secured. The actual dynamic range of the amplifier depends on the method of selecting the input range of the functional unit 18. Generally, the amplifier located at the input stage distributes a wider input range, and the input range becomes narrower toward the output stage. Yes, with such a configuration, the dynamic range can be further expanded.

FIG. 12 is a diagram for easily explaining the operation of the multi-stage limiter amplifier of FIG.
The graph shown by is the amplitude transmission characteristic of the functional unit on the output stage side, FIG. 12B is the amplitude transmission characteristic of the unit located on the previous stage side of the functional unit of FIG.
(C) is an amplitude transmission characteristic of a unit located at a stage preceding the functional unit of FIG. 11 (b). When an input in the range of X1 enters the functional unit shown in FIG. 12C, the amplitude is compressed and output as Y1. This Y1 becomes the input of the next stage, and is compressed as Y2 as shown in FIG. 12B, and finally compressed to Y3 in the third stage as shown in FIG. 12A. Therefore, the amplifier located at the forefront stage does not need to completely compress the output in the input range, and as a result, the dynamic range can be effectively expanded in the entire multi-stage limiter amplifier.

[0009]

In a conventional limiter amplifier, a self-bias feedback resistor 12 for suppressing a gate current flowing during a limiter operation and a feedback resistor 12 are connected in a gate bias circuit. There is a time constant determined by the determined capacitance of the capacitor 4a.
The time constant is represented by the product of the feedback resistor 12 and the capacitor 4a. If a product of 20 kΩ and 100 picofarads is assumed for a general small signal transistor, the time constant is 2 microseconds. This time constant may fluctuate the rising characteristic of the signal when two types of signals having different amplitudes are transmitted, that is, when the input amplitude of the limiter changes in a certain cycle. Since the choke coil 3a is several nanohenries with respect to the time constant described above, there may be small vibrations in the transient characteristics, but there is no great influence.

FIG. 13A shows a transmission state of two kinds of signals having different amplitudes, and FIG. 13B shows a transient characteristic when the transmission signal of FIG. 13A is processed by a limiter amplifier. It is. FIG. 13B shows a phenomenon in which the rising characteristic of a small input signal immediately after an input signal having a large amplitude fluctuates. Originally, it is ideal that the output power of the limiter amplifier is fixed irrespective of the magnitude of the transmission signal, but in FIG. 13B, the communication information included in the small signal fluctuates, and as a transient response, Is not preferred.

FIG. 14 shows the drain voltage versus current characteristic of the static characteristics of the transistor, and is a diagram for explaining the cause of the transient characteristic shown in FIG. In the case of the drain voltage VD1 in FIG. 14, if the bias setting of the transistor in the linear operation is point A, the transition to the point B occurs in the limiter operation due to the feedback voltage generated by the feedback resistor 12. This is because the bias point changes during the limiter operation of the amplifier and the gate voltage is drawn in the negative direction as described with reference to FIG. Drain current IDS1 at point A
Moves to the IDS2 at the point B, which means that the gain of the transistor is reduced. As long as the bias condition at the point B is maintained by a time constant circuit or the like, the gain remains reduced.

FIG. 15 is a diagram showing the relationship between the drain current and the gain of the transistor. The transition of the drain current IDS1 at point A shown in FIG. 14 to the IDS2 at point B causes a decrease in the linear gain of the amplifier. Is shown.

The present invention has been made to solve such a problem, and has as its object to obtain a limiter amplifier having a good transient response and a wide dynamic range.

[0014]

A limiter amplifier according to a first aspect of the present invention uses, instead of a self-bias resistor of a conventional limiter amplifier, a detection diode whose detection current changes in accordance with the amplitude of an input signal. It is incorporated in a gate bias circuit of a transistor as a current source for generating a voltage.

In the limiter amplifier according to the second invention, the detection diode of the limiter amplifier according to the first invention is replaced with a detection transistor whose gate current changes in accordance with the amplitude of an input signal, and a feedback voltage is generated. Is incorporated in a gate bias circuit of a transistor as a current source.

A limiter amplifier according to a third aspect of the present invention includes a drain bias circuit of the limiter amplifier according to the first aspect of the present invention, in which a drain resistance that satisfies certain conditions and that can perform voltage feedback in accordance with a change in drain current is incorporated. is there.

A limiter amplifier according to a fourth aspect of the present invention is one in which a drain resistor which satisfies certain conditions and performs voltage feedback in accordance with a change in drain current is incorporated in the drain bias circuit of the limiter amplifier shown in the conventional example. is there.

A limiter amplifier according to a fifth aspect of the present invention is obtained by connecting the limiter amplifiers according to the third or fourth aspect of the invention in multiple stages.

In a limiter amplifier according to a sixth aspect of the present invention, the drain resistance of the fifth multi-stage amplifier is replaced with a thermistor whose resistance value changes with temperature.

In a limiter amplifier according to a seventh aspect of the present invention, the drain resistance of the fifth multistage amplifier is replaced with a bias transistor whose resistance can be varied by an external bias.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a limiter amplifier according to the first invention, wherein 1 to 5, 7, and 8 are functional components similar to those in FIG. 8, 9 is a branch circuit for branching a part of a transmission signal, and 6
Denotes a detection diode for detecting a signal branched by the branch circuit 9. According to the first aspect, the detection diode 6 whose detection current changes according to the amplitude of the input signal is incorporated in the gate bias circuit of the transistor 1 as a current source for generating a feedback voltage. The voltage calculated as the product of the bleeder resistance 5 and the detection current biases the gate in the negative voltage direction. By biasing the gate in the negative voltage direction, it acts in the direction of decreasing the gate current IG of the transistor 1 and reduces an undesired effect called migration on reliability.
Here, the operation of the circuit will be described. The transmission signal branched from the branch circuit 9 is input to the detection diode 6, and a detection current corresponding to the power level flows through the diode 6. The bleeder resistor 5 is selected to be sufficiently smaller than the feedback resistor 12 described in the related art, and instead, a detection current that is sufficiently larger than the gate current IG is caused to flow through the bleeder resistor 5.
On the premise that a feedback voltage equivalent to that of the prior art is generated in the bleeder resistor 5, the choke coil 3
The time constant determined by b, the bleeder resistance 5, the capacitors 4a and 4b, the internal resistance of the detection diode 6, and the like can be reduced. As a result, it is possible to improve the transmission transient characteristic of a signal whose amplitude changes with time, which is the problem described with reference to FIG. Since the detection diode 6 directly detects the transmission signal, it shows a good response to a change in the amplitude of the transmission signal. When the amplitude of the transmission signal changes from a large state to a small state, the detection current decreases instantaneously. I do. Since the internal resistance of the detection diode 6 is usually several hundred ohms, the time constant can be reduced to several% as compared with the case of the related art, and as a result, it can be reduced to several tens of nanoseconds. The branch circuit 9 may be a simple passive circuit, but may be an active circuit having an amplifying function.

Embodiment 2 FIG. FIG. 2 shows a limiter amplifier according to the second aspect of the present invention. Reference numerals 1 to 5, 7 to 9 denote functional components similar to those in FIG. 1, and 10 denotes a detection transistor for detecting a signal branched by the branch circuit 9. According to the second invention, the same effect as the first invention is realized by replacing the detection diode 6 of FIG. 2 used in the first invention with the detection transistor 10. In the detection transistor 10, both the drain and source terminals are short-circuited, and the Schottky junction between the gate terminal and the short-circuited drain and source terminals exhibits diode characteristics. By utilizing this diode characteristic and obtaining a detection current corresponding to a change in the amplitude of the transmission signal as a gate current, the same effect as that of the first invention is obtained.

Embodiment 3 FIG. FIG. 3 shows a limiter amplifier according to the third invention, wherein 1 to 9 are the same functional components as in FIG. 1, respectively, and 11 is a second power supply 8 and a third choke coil 3.
3 shows a drain resistor connected between the terminals c and c for performing voltage feedback. According to the third aspect of the present invention, the drain used in the circuit used in the first aspect of the invention is connected between the second power supply 8 and the third choke coil 3c and has a drain resistor 11 for performing voltage feedback. The time constant improved by the first invention can be completely compensated. FIG. 14 shows the state of the bias setting of the transistor 1. In the drain voltage VD1, the gate voltage indicated by the point A transitions to the voltage B by the feedback voltage generated by the bleeder resistor 5 and the detection current. Accordingly, the drain current changes from ID1 to ID2. Here, if the drain voltage can be changed from VD1 to VD2 and the drain current can be set to the point C, the drain current returns to the same numerical value ID1 as the point A, and the change in the linear gain as shown in FIG. prevent. As described with reference to FIG. 10D, the drain current of the limiter amplifier tends to decrease during the limiter operation. However, if the drain resistor 11 is used, when the drain current decreases, the drain voltage of the transistor 1 increases and VD1 From VD2 to VD2. The optimum value of the drain resistance 11 is obtained by dividing the voltage difference from VD1 to VD2 by the drain current decrease. FIG. 8 is a diagram for explaining a change state of the output power, the drain current, and the drain voltage of the transistor before and after using the drain resistor 11. The dashed line indicated as “improved” indicates the characteristic of the limiter amplifier using the drain resistor 11. Since the drain current is controlled to the same value between the input points A and B at the start of saturation, the drain voltage is reduced. Is changing.

Embodiment 4 FIG. 4 shows a limiter amplifier according to the fourth invention, wherein 1 to 5, 7, 8, and 12 are functional components similar to those of FIG. 9, and 11 is a second component of the second power supply 8 and choke coil 3c as shown in FIG. 5 shows a drain resistor connected between the terminals and for performing voltage feedback. According to the fourth aspect of the present invention, a drain resistor 1 that satisfies certain conditions and can perform voltage feedback according to a change in drain current is provided in the drain-side bias circuit of the conventional limiter amplifier of FIG.
By incorporating 1, the effect of the time constant existing in the gate bias circuit is compensated, and a change in the linear gain of the limiter amplifier is prevented as in the third invention. Here, the condition required for the drain resistor 11 is as follows: first, the feedback resistor 12
Is the product of the drain resistance 11 and the fourth capacitor 4a.
And that the change in the drain voltage caused by the change in the gate current of the transistor 1 during the limiter operation is divided by the decrease in the drain current. Will be done.
By satisfying the above two conditions, a simplified circuit can be realized as compared with any of the first to third inventions, since the detection component and its peripheral components are not required.

Embodiment 5 FIG. FIG. 5 shows a limiter amplifier according to the fifth aspect of the invention. Reference numeral 13 denotes a functional unit in which the limiter amplifier shown in FIG. 3 or FIG. 4 excluding the drain bias circuit is represented as one unit, and the other units are the same as those in FIG. 3 or FIG. Shows functional components. According to the fifth aspect, the limiter amplifier according to the third or fourth aspect is connected in multiple stages, thereby improving the transmission transient characteristic of a signal whose amplitude changes with time. Thus, it is possible to expand the dynamic range of the limiter amplifier. Each functional unit 13 selects the optimum constant of the drain resistor 11 and the capacitor 4 for each functional unit according to the range of the input power, as described in the third or fourth invention. Here, depending on the range of the input power, it is not necessary to use the drain resistor 11 for all the functional units, and the resistor 11 may be connected only to the unit whose transient characteristic is to be improved.

Embodiment 6 FIG. FIG. 6 shows a limiter amplifier according to a sixth aspect of the present invention. Reference numeral 14 denotes a thermistor connected in place of the drain resistor in FIG. 5, and other components are the same as those in FIG. 3 or FIG. According to the sixth invention, the junction temperature of the transistor 1 inside the functional unit usually rises by replacing the drain resistor 11 of FIG. 5 according to the fifth invention with a thermistor 14 whose resistance value changes with temperature. Then, the saturation output power, which decreases, can be compensated, and the temperature can be stabilized. In this case, it is effective to use a thermistor 14 having a negative polarity in which the resistance value decreases as the temperature rises, but this is not the case when it is desired to change the limiter output with the temperature.

Embodiment 7 FIG. 7 shows a limiter amplifier according to a seventh aspect of the present invention. Reference numeral 15 denotes a bias transistor connected in place of the drain resistor 11 of FIG. 5, and reference numeral 16 denotes a bias voltage of the bias transistor 15 which can be varied in accordance with operating conditions of the limiter amplifier. Is a variable voltage power supply, and 17 is a voltage controller for controlling the variable voltage power supply 16. The variable voltage power supply 16 and the voltage controller 17 are connected to the respective bias transistors 15.
Although a part is provided for a to 15c, a part thereof is omitted and described here. According to the seventh aspect, the time constant at the time of transient response can be freely varied by replacing the drain resistor 11 of FIG. 5 according to the fifth aspect with the bias transistor 15 whose resistance value can be varied by an external bias. Alternatively, the temperature can be stabilized by compensating for the saturation output power that changes with temperature. The voltage controller 17 controls the variable voltage power supply 16 and controls the biasing transistor 15 so that when the junction temperature of the transistor 1 increases, the series resistance value in the drain current path decreases, and the drain voltage itself increases. . As a result, the limiter output is stabilized by temperature. The function of the voltage controller 17 itself can be used not only for stabilizing the temperature as described above, but also for actively changing the limiter output by an external command. The biasing transistor 15 has an effect of realizing a resistance element having a high power resistance and a low resistance value even when a transistor having a low drain impedance is used. Although the bias transistor 15 is shown as a bipolar transistor, a field effect transistor,
Use of a thyristor or the like is also possible.

[0028]

According to the first aspect of the invention, the detection diode on the circuit generates a detection current, and the voltage calculated as the product of the detection current in the bleeder resistor biases the gate of the transistor in the negative voltage direction. This has the effect of improving the reliability of the amplifier by reducing the gate current of the transistor and at the same time improving the transient response.

According to the second invention, the detection transistor on the circuit generates a detection current, and the voltage calculated as the product of the detection current at the bleeder resistor biases the gate of the transistor in the negative voltage direction. This has the effect of improving the reliability of the amplifier by reducing the gate current of the transistor and at the same time improving the transient response.

Further, according to the third aspect, the drain resistance on the circuit compensates for the time constant generated in the gate bias circuit of the transistor at the time of the transient response of the limiter amplifier, and the transient response of the limiter amplifier is improved to the optimum state. There is.

Further, according to the fourth aspect, the first to third aspects are provided.
By the simplified circuit compared to any of the inventions,
The drain resistance compensates for the influence of the time constant existing in the gate bias circuit, and has the effect of improving the transient response of the limiter amplifier to the optimum state.

According to the fifth aspect of the present invention, the multistage limiter amplifier has an effect of expanding the dynamic range of the amplifier during the limiter operation and improving the transient response of the limiter amplifier to the optimum state by the drain resistance.

According to the sixth aspect of the present invention, the multistage limiter amplifier expands the dynamic range of the amplifier at the time of the limiter operation, and the thermistor improves the transient response of the limiter amplifier to an optimum state. This has the effect of compensating for a change in the resulting saturated output power and stabilizing against temperature.

According to the seventh aspect, the multistage limiter amplifier expands the dynamic range of the amplifier during the limiter operation, and the bias transistor is controlled by an external controller so that the transient response of the limiter amplifier is optimized. This has the effect that the temperature can be stabilized and the limiter output can be positively changed.

[Brief description of the drawings]

FIG. 1 is a first embodiment of a limiter amplifier according to the present invention;
FIG.

FIG. 2 is a limiter amplifier according to a second embodiment of the present invention;
FIG.

FIG. 3 is a limiter amplifier according to a third embodiment of the present invention;
FIG.

FIG. 4 is a limiter amplifier according to a fourth embodiment of the present invention;
FIG.

FIG. 5 is a limiter amplifier according to a fifth embodiment of the present invention;
FIG.

FIG. 6 is a limiter amplifier according to a sixth embodiment of the present invention;
FIG.

FIG. 7 is a limiter amplifier according to a seventh embodiment of the present invention;
FIG.

FIG. 8 is a limiter amplifier according to a third embodiment of the present invention;
FIG. 9 is a diagram for explaining a change state of the output power, the drain current, and the drain voltage of the transistor with respect to the input power in the cases of FIGS.

FIG. 9 is a diagram showing a circuit of a conventional limiter amplifier.

FIG. 10 is a diagram illustrating a change state of output power, gate and drain current, and gate voltage with respect to input power of a transistor used in a conventional limiter amplifier.

FIG. 11 is a diagram showing a configuration in which conventional limiter amplifiers are connected in multiple stages.

FIG. 12 is a diagram showing a change state of input and output when a conventional limiter amplifier is connected in multiple stages.

FIG. 13 is a diagram showing a transient characteristic of output power when a conventional limiter amplifier processes a transmission signal whose amplitude changes with time.

FIG. 14 shows a transistor used in a limiter amplifier.
FIG. 4 is a diagram illustrating a state of bias setting.

FIG. 15 shows a transistor used in a limiter amplifier.
FIG. 9 is a diagram illustrating characteristics of a linear gain with respect to a bias setting.

[Explanation of symbols]

1 transistor, 2 matching circuit, 3 choke coil, 4 capacitor, 5 bleeder resistor, 6 detection diode, 7 first power supply, 8 second power supply, 9 branch circuit,
10 detection transistor, 11 drain resistance, 12
Resistor for self-bias feedback, 13 Functional unit excluding drain bias circuit, 14 Thermistor, 15 Bias transistor, 16 Variable voltage power supply, 17 Voltage controller, 18 Limiter amplifier functional unit.

Claims (7)

[Claims] A matching circuit connected to the input / output terminal and the input / output terminal; a transistor connected to the matching circuit; a first choke coil connected to a gate terminal of the transistor; A first capacitor connected to the first choke coil and having one end grounded; a bleeder resistor connected in parallel to a connection point between the first choke coil and the first capacitor and having one end grounded; A second power supply, a first power supply grounded at one end for supplying a voltage to a gate terminal of the transistor, a third capacitor connected in parallel to the first power supply, and a second power supply. A detection diode and a second choke coil connected between the non-ground side terminals of the third capacitor, and an input terminal for branch-connecting a signal to the detection diode A third branch connected to the drain terminal of the transistor, a fourth capacitor connected to the third choke and grounded at one end. A second power supply connected in parallel to the fourth capacitor. 2. A matching circuit connected to the input / output terminal and the input / output terminal, a transistor connected to the matching circuit, a first choke coil connected to a gate terminal of the transistor, A first capacitor connected to the first choke coil and having one end grounded; a bleeder resistor connected in parallel to a connection point between the first choke coil and the first capacitor and having one end grounded; A second power supply, a first power supply grounded at one end for supplying a voltage to the gate terminal of the transistor, a third capacitor connected in parallel to the first power supply, and a second power supply connected to the first power supply. A second choke coil connected in series, and a gate terminal of the second capacitor,
A detection transistor having a drain terminal and a source terminal connected to the second choke coil; a branch circuit connected between the input terminal and the detection transistor for branching and connecting a signal to the detection transistor; A third choke coil connected to the drain terminal of the third choke coil, a fourth capacitor connected to the third choke coil and having one end grounded, and a second power supply connected in parallel to the fourth capacitor. And a limiter amplifier. 3. The limiter amplifier according to claim 1, further comprising a drain resistor between a non-ground terminal of said fourth capacitor and said second power supply. 4. A matching circuit connected to the input / output terminal and the input / output terminal, a transistor connected to the matching circuit, a first choke coil connected to a gate terminal of the transistor, A first capacitor connected to the first choke coil and having one end grounded; a bleeder resistor connected in parallel to a connection point between the first choke coil and the first capacitor and having one end grounded; A first power supply grounded at one end for supplying a voltage to a gate terminal of the transistor;
A negative electrode side terminal of the power supply and a non-grounded terminal of the bleeder resistor, and a self-bias feedback resistor connected between the first capacitor and the non-grounded terminal of the bleeder resistor;
A second choke coil connected to the drain terminal of the transistor, a second capacitor connected to the second choke coil and one end of which is grounded;
And a second power supply connected between the drain resistance and the ground, the drain resistance being connected to a non-ground terminal of the capacitor and satisfying a specified condition. 5. The limiter amplifier according to claim 3, wherein the limiter amplifiers are connected in multiple stages, and each of the limiter amplifiers has a combination of a drain resistor and a fourth capacitor that are optimal for operating conditions of each limiter amplifier. Characteristic limiter amplifier. 6. The limiter amplifier according to claim 5, wherein each of the drain resistance portions of the multi-stage limiter amplifier has a separate thermistor whose resistance value changes with temperature and which is optimal for the operation condition of each limiter amplifier. And limiter amplifier. 7. The limiter amplifier according to claim 3, wherein the limiter amplifiers are connected in multiple stages, and the second power supply and the third choke coil of one or more limiter amplifiers in the multistage connected limiter amplifiers are connected. A bias transistor connected to a drain resistance portion between
A variable voltage power supply connected to a terminal different from the two terminals of the transistor for varying the DC resistance between the two terminals of the bias transistor in accordance with the operating conditions of the respective limiter amplifiers; A limiter amplifier comprising a voltage controller that controls a voltage power supply.