JPH10111354A - High-frequency amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a phase variation even in the case of the fluctuation of an input level for effectively restraining a side band by providing a transmit amplifier with a limiter for limiting the amplitude of an input high-frequency signal to a fixed value. SOLUTION: A high-frequency amplifier is provided with a limiter 2 which limits the amplitude of an input high-frequency signal to a fixed value by a plurality of transmit amplifiers used in an active electronic scanning type pulse radar device. In addition, the wave form 5 of a bias voltage applied to the final stage amplifying element is pulse-shapedly formed. Namely, an input high- frequency signal wave form 1 is turned into a signal having a fixed level by absorbing an input fluctuation through the limiter 2, and the above signal is inputted into an electric power amplifier 3 acting in a nonlinear domain. In this case, the wave form 5 of a bias voltage applied to the electric power amplifier 3 is made slower in a rising and a trailing speed, and an output high-frequency signal wave form 4 is made slower in a rising and a trailing speed, and the occurrence of the side band can be therefore prevented. Many electric power amplifiers 3 are arranged to form the active electronic scanning type pulse radar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION An object of the present invention is to provide a high-frequency amplifier used for a transmission amplifier such as a pulse radar.

[0002]

2. Description of the Related Art An example of an active electronic scanning pulse radar apparatus is shown in FIG. In FIG. 4, reference numeral 11 denotes a high-frequency signal generator having a pulse modulation function (hereinafter, referred to as a pulse modulation wave generation circuit). A pulse modulation wave output from the pulse modulation wave generation circuit 11 is a filter for sideband suppression. 12 removes the sideband frequency band. After the output of the filter 12 is distributed by n through the distribution path 13, the phase is controlled by phase shifters 141 to 14n, and linearly amplified by linear amplifiers 151 to 15n.
Radiated from 1 to 16n.

In addition, a non-linear amplifier is used,
It is also conceivable to provide a side band suppression function behind it. FIG. 5 shows an example. In FIG. 5, the same portions as those in FIG. 4 are denoted by the same reference numerals, and duplicate description will be omitted.

In FIG. 5, n phase shifters 141 to 14 are provided.
The pulse-modulated wave whose phase is controlled by n is amplified by nonlinear amplifiers 171 to 17n, sideband frequencies are removed by sideband suppression filters 181 to 18n, and transmitted from antenna elements 161 to 16n.

A plurality of power amplifiers used in an active electronic scanning pulse radar device are often operated in a non-linear region in order to increase efficiency. For this reason, if there is a variation in the input power level due to a variation in the distributor, a variation in the loss of the phase shifter, a temperature change, a frequency change, etc., a phase change occurs due to the AM / PM characteristic, which adversely affects the formation of the transmission beam. Was.

Here, the AM / PM characteristic means that when an input signal level is changed (amplitude modulation) while an amplifier is operating in a nonlinear region, a passing phase is changed (subject to phase modulation).
Characteristics.

[0007] In a radar apparatus for transmitting a pulse-modulated signal, sidebands associated with pulse modulation are generated outside the band occupied by the radar, and this may cause radio interference to peripheral communication devices and the like. In order to avoid this interference, in a conventional radar apparatus, pulse amplitude waveform shaping is performed as a method for reducing the occurrence of side bands.

FIG. 6 shows one example of this, in which the rising and falling speeds of the output pulse modulated wave 4 are reduced by applying a pulse 7 having a shaped amplitude waveform to the input to lower the side band generation level. I have. However, in this case, it is necessary to operate the amplifier 8 in a linear region in order to amplify while maintaining the input pulse amplitude waveform, and power efficiency is poor. Therefore, when the power amplifier is operated in a non-linear region in order to avoid the deterioration of efficiency, even if the input signal 7 is shaped into a pulse amplitude waveform as shown in FIG. It has the disadvantage that it is deformed and the sideband level is increased again.

[0009]

As described above, when the power amplifier is operated in the non-linear region, a phase change occurs due to an input level change, which has an adverse effect on the formation of a transmission beam, and a pulse amplitude waveform shaping of an input signal. Even if you give
There is a disadvantage that the pulse amplitude waveform changes and the sideband level increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawback, and prevents a phase change from occurring even if an input level fluctuates when a power amplifier is operated in a non-linear region.
The purpose is to effectively suppress sidebands.

[0011]

In order to achieve the above object, the present invention provides a plurality of transmission amplifiers used in an active electronic scanning type pulse radar device, comprising a limiter for limiting the amplitude of an input high frequency signal to a constant value. And applying a shaped bias voltage to at least the final stage amplifying element of the amplifier to shape the amplitude waveform of the output high-frequency signal into a desired pulse shape.

In addition, a limiting amplifier is used in place of the limiter to amplify the amplitude of the input high-frequency signal and limit the amplitude to a constant amplitude.

The transmission amplifier is constituted by a limiting amplifier, and a pulse-like bias voltage applied to the limiting amplifier is controlled.

Further, the invention is characterized in that a gallium arsenide field effect transistor is used for the amplifying element.

Further, the amplifier is operated in a non-linear region.

In the high-frequency amplifier configured as described above,
A limiter is provided before the power amplifier operating in the non-linear region to keep the input level constant, thereby preventing a phase change due to AM / PM characteristics of the power amplifier.

Also, by forming a bias voltage waveform applied to at least the final stage amplifying element of the power amplifier into a pulse shape, and forming an output high-frequency signal waveform into a pulse shape to prevent generation of a side band, good performance can be obtained. A high-frequency amplifier can be realized.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. An input high-frequency signal waveform 1 is input to a power amplifier 3 operating in a non-linear region as a signal of a constant level by absorbing input fluctuations by a limiter 2. The power amplifier 3 uses a plurality of amplifying elements, and uses a gallium arsenide field effect transistor as at least one of the amplifying elements. At this time, the bias voltage waveform 5 applied to the power amplifier 3 slows the rising and falling speeds, and the rising and falling speeds of the output high-frequency signal waveform 4 to prevent the generation of sidebands, thereby achieving good performance. A high-frequency amplifier can be realized. This power amplifier 3 is connected to 171 to 17 in FIG.
The active electronic scanning type pulse radar is formed by arranging a large number as in n.

In the above description, the case where the limiter 2 is used to keep the input level of the power amplifier 3 operating in the nonlinear region constant has been described. However, the same effect can be obtained by using a limiting amplifier 6 that amplifies the amplitude of an input high-frequency signal and limits the amplitude to a constant amplitude instead of the limiter 2.

Another embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows an example in which the present invention is applied to the limiting amplifier 6 and the power amplifier 3 operating in a nonlinear region. It is the same as FIG. 1 except that a limiting amplifier 6 that amplifies the amplitude of an input high-frequency signal and limits the amplitude to a constant amplitude is used instead of the limiter 2.

Further, another embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, the rising and falling speed of the pulse of the pulsed bias voltage waveform 5 supplied to the limiting amplifier 6 is appropriately controlled to be slow,
Accordingly, a similar effect can be obtained by appropriately controlling and reducing the rising and falling speed of the pulse amplitude waveform 4 of the output high-frequency signal. FIG. 3 shows an example in which the present invention is applied to the limiting amplifier 6.

[0024]

According to the present invention, it is possible to realize a high-frequency amplifier having a small phase change with respect to an input level fluctuation and a small generation of sidebands and having good performance.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating another embodiment of the present invention.

FIG. 3 is a diagram illustrating another embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional example.

FIG. 5 is a diagram illustrating a conventional example.

FIG. 6 is a diagram illustrating a conventional example.

FIG. 7 is a diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Input high frequency signal waveform 2 ... Limiter 3 ... Power amplifier which operates in a non-linear area 4 ... Output high frequency signal waveform 5 ... Bias voltage waveform 6 ... Limiting amplifier 7 ... Pulse amplitude shaped high frequency signal waveform 8 ... In a linear area Operating amplifier 9: Output high-frequency signal waveform whose waveform envelope is deformed 11: Pulse modulation wave generating circuit 12: Sideband suppression filter 13: Distribution path 141 to 14n: Phase shifter 151 to 15n: Linear amplifier 161 to 16n: Antenna Element 171 to 17n Nonlinear amplifier 181 to 18n Sideband suppression filter

Claims (5)

[Claims] 1. A plurality of transmission amplifiers used in an active electronic scanning pulse radar device, comprising: a limiter for limiting an amplitude of an input high-frequency signal to a constant value, and a pulse-shaped pulse formed in at least a final-stage amplification element of the amplifier. A high-frequency amplifier for applying a bias voltage and shaping the amplitude waveform of an output high-frequency signal into a desired pulse shape. 2. The high-frequency amplifier according to claim 1, wherein a limiting amplifier that amplifies the amplitude of the input high-frequency signal and limits the amplitude to a constant amplitude is used instead of the limiter. 3. The high-frequency amplifier according to claim 1, wherein the transmission amplifier comprises a limiting amplifier, and controls a pulse-like bias voltage applied to the limiting amplifier. 4. The high-frequency amplifier according to claim 1, wherein a gallium arsenide field effect transistor is used as the amplifying element. 5. The high-frequency amplifier according to claim 1, wherein the amplifier is operated in a nonlinear region.