RU21703U1 - WIDE BAND POWER AMPLIFIER WITH AUTOMATIC ADJUSTABLE CURRENT ADJUSTMENT - Google Patents

Abstract

A broadband power amplifier with automatic adjustment of the current consumption, containing the first amplifier element, the common electrode of which is connected to the common bus, the input electrode is connected to the signal source through the input correction circuit, the output electrode is connected to the input of the output correction circuit and through the serial connection of the inductor and the first resistor - with a power source, and the connection point of the inductor and the first resistor through the first capacitor is connected to a common bus, a detector, the input of which is connected n with the first output of the second capacitor and through the initial bias circuit to the power source, and the output is connected to the input electrode of the second amplifier element, the common electrode of which is connected to the connection point of the inductor and the first resistor, and the output electrode is connected through the second resistor to the input electrode of the first amplifier element, characterized in that a directional coupler of the incident wave and a corrector are inserted into it, the input of the directional coupler is connected to the output of the output correction circuit, the output to the load minutes, branch power output - to an input of the equalizer and the ballast output - with a ballast load output equalizer connected to the second terminal of the second capacitor.

Description

WIDE BAND POWER AMPLIFIER WITH AUTOMATIC ADJUSTABLE CURRENT ADJUSTMENT

The invention relates to radio engineering, in particular to radio communication technology, broadband radar, and can be used, for example, as output units of signal generators, in broadband devices of telecommunication equipment.

A wide-band amplifier with oscillations with automatic adjustment of current consumption is known, it contains an amplifying element, the common electrode of which is connected to a common bus, the input electrode is connected to a signal source through an input correction circuit, and the output electrode is connected to a load through an output correction circuit and through a choke with a power source, a detector whose input is connected to the load, and the output to the input of a DC amplifier, the output of which is connected through a resistor to the input electrode of the amplifier Item 1, p. 258, fig. 10.11. However, the known device does not provide the maximum possible output power, due to the influence of the detection effect on the operation of the control system 2, p. 11, it has a reduced efficiency when working on an inconsistent high-resistance load, leads to distortion of the amplified signal when working on an inconsistent low-resistance load , does not provide protection against idling load.

The closest in technical essence and the achieved result to the proposed solution is a broadband power amplifier with automatic adjustment of the current consumption, containing the first amplifier element, the common electrode of which is connected to a common bus, the input electrode is connected to the source through the input correction circuit with the load and through the serial connection of the inductor and the first resistor with a power source, and the connection point of the inductor and the first resistor through the first capacitor is connected to bus, a detector, the input of which through the second capacitor is connected to the load and through the initial bias circuit to the power source, and the output to the input electrode of the second amplifier element, the common electrode of which is connected to the connection point of the inductor and the first resistor, and the output electrode is connected through the second resistor with an input electrode of the first amplifying element 2, p. 11, Fig. 4. However, the known amplifier has a reduced efficiency when working on an inconsistent high-resistance load, leads to distortion of the amplified signal when working on an inconsistent low-resistance load, does not provide protection against idling of the load.

The inventive broadband power amplifier with automatic adjustment of the current consumption, containing the first amplifier element, the common electrode of which is connected to a common bus, the input electrode is connected to the signal source through the input correction circuit, the output electrode is connected to the input of the output correction circuit and through the serial connection of the inductor and the first resistor with a power source, and the connection point of the inductor and the first resistor through the first capacitor is connected to a common bus, a detector, the input of which ohm is connected to the first terminal of the second capacitor and through the initial bias circuit with a power source, and the output is with the input electrode of the second amplifier element, the common electrode of which is connected to the connection point of the inductor and the first resistor, and the output electrode is connected through the second resistor to the input electrode of the first amplifier element , a directional coupler of the incident wave and a corrector are introduced, the input of the directional coupler is connected to the output of the output correction circuit, the output is with load, the output of the branch power with the corrector input, and the ballast output with ballast load, the corrector output is connected to the second output of the second capacitor.

The introduced directional coupler can be made, for example, on the basis of a segment of a two-wire transmission line wound around a metal tube 3, the corrector can be made, for example, on the basis of an amplification stage with parallel negative voltage feedback 4, p. 69.

By introducing a directional coupler and corrector, the efficiency is increased when working on an inconsistent high-resistance load, eliminating distortion of the amplified signal when working on an inconsistent low-resistance load, and protection against idling of the load.

In FIG. Figure 1 shows a functional diagram of the proposed broadband amplifier with automatic control of the current consumption. In FIG. 2 presents a functional diagram of the prototype. In FIG. 3 is a schematic diagram of an experimental prototype of a broadband power amplifier with automatic adjustment of current consumption, having the following technical characteristics: operating frequency band 10-50 MHz; gain of 16 dB; non-uniformity of the amplitude-frequency characteristic +0.5 dB; rated output power level 4 W; silent current consumption 0.1 A; in nominal output power mode of 0.55 A. FIG. 4 shows the experimental dependence of the output power of the amplifier shown in FIG. 3, from load resistance, at a constant input signal level. In FIG. 5 shows the experimental dependence of the current consumed by the amplifier shown in FIG. 3, from load resistance, at a constant input signal level. In FIG. 6 shows the experimental dependence of the current consumed by the amplifier shown in FIG. 3, from the level of its output voltage, when working on a coordinated 50ohm load.

A broadband power amplifier with automatic adjustment of the current consumption contains a first amplifier element 1, the common electrode of which is connected to a common bus, the input electrode is connected to a signal source 3 through an input correction circuit 2, the output electrode is connected to the input of the output correction circuit 4, and through a series connection of the inductor 5 and the first resistor 6 with a power source, and the connection point of the inductor 5 and the first resistor 6 through the first capacitor 7 is connected to a common bus, a detector 8, the input of which connected to the first output of the second capacitor 9 and through the initial bias circuit 10 with a power source, and the output with the input electrode of the second amplifier element 11, the common electrode of which is connected to the connection point of the inductor 5 and the first resistor 6, and the output electrode through the second resistor 12 is connected to the input electrode of the first amplifier element 1, a directional incident wave coupler 13, the input of which is connected to the output of the output correction circuit 4, the output with load 14, the output of the branch power with the input of the corrector 15, and allastny ballast output load 16, the output of the corrector 15 is connected to the second terminal of the second capacitor 9.

Broadband power amplifier with automatic adjustment of current consumption works as follows. In silent mode, the current consumed by the first amplifier element 1 is set by the initial bias circuit 10, is selected to be minimal, and in accordance with 5.6 it is determined from the relation:

Kmin to max (where v | / is the current transistor utilization factor; to the current max; J PKdop I H () is the maximum value of the consumed voltage transistor utilization factor; P f when the signal from signal source 3 is input to the amplifier, it goes through the input correction circuit 2, which forms the amplitude-frequency characteristic of the amplifier, and is amplified by the first amplifier element 1. The amplified signal through the output correction circuit 4, which eliminates the influence of the output capacitance of the first amplifier element 1 on the level n output power 5, as well as performing the breaking of the feedback loop by the control signal 6, and through the directional coupler 13 enters the load 14. Part of the amplified signal from the output of the branch power of the directional coupler 13 is fed to the input of the corrector 15. The central frequency of the directional coupler 13 is selected more the upper cut-off frequency of the broadband power amplifier. Therefore, the transient attenuation of the directional coupler is maximally at the lower cut-off frequency of the broadband power amplifier and decreases with an increase in the frequency of the amplified signal by 6 dB per octave 4. The transmission coefficient of the corrector 15 is selected to decrease with an increase in the frequency of the amplified signal by 6 dB per octave. As a result, the input of the detector 8 receives a signal proportional to the level of the output voltage and independent of the frequency of the amplified signal. The detected signal from the detector 8 is fed to the input electrode of the second amplifier element 11, opening it and thereby increasing the current of the input electrode of the first amplifier element 1, which leads to an increase in the current flowing through the output electrode of the first amplifier element 1. A circuit consisting of a second amplifier element 11 and the second resistor 12, is a negative feedback circuit 2 for direct current. The control signal from detector 8 changes the depth of feedback by changing the amount of direct current flowing through the output electrode of the first amplifier element 1.

In accordance with 6, the time constant of the detector 8 should be selected from the ratio:

where ω „is the lower boundary circular frequency of the passband of the broadband power amplifier. In this case, when the modulation frequencies of the carrier oscillation are less than oops consumed by the first amplifier element 1, it changes according to the modulation law. When amplifying signals with a modulation frequency of more than the detector 8 goes into peak detection mode and the current consumed by the first amplifier element 1, at a constant input signal level, remains constant.

In FIG. 3 is a schematic diagram of an experimental prototype of a broadband power amplifier with automatic adjustment of current consumption, implemented according to the structural diagram (Fig. 1) of the proposed broadband power amplifier with automatic adjustment of current consumption. With an amplifier bandwidth of 10-50 MHz, the central operating frequency of the directional coupler 13 is selected to be 200 MHz.

Pa FIG. 4 shows the experimental dependence of the output power of the amplifier layout on the load resistance 14 at a constant level of the input signal (curve 1). The experimental dependences of the output power of the amplifier layout on the load resistance 14 during its implementation in the mode with a fixed operating point (curve 2) and during the implementation of the amplifier according to the prototype scheme (curve 3) are also given here.

Pa FIG. Figure 5 shows the experimental dependence of the current consumed by the amplifier model on the load resistance 14 at a constant input signal level (curve 1). The experimental dependences of the current consumed by the prototype of the amplifier on the resistance of the load 14 when it is implemented in the mode with a fixed operating point (curve 2) and when the amplifier is implemented according to the prototype scheme (curve 3) are also given here.

Pa FIG. Figure 6 shows the experimental dependence of the current consumed by the amplifier layout on the level of its output voltage when operating at a coordinated 50-ohm load (curve 1). The experimental dependences of the current consumed by the amplifier model on

the level of its output voltage, when working on a coordinated 50-ohm load and when implementing the amplifier in a mode with a fixed operating point (curve 2) and according to the prototype scheme (curve 3).

A sharp drop in the output power in the prototype during its operation on an inconsistent low-impedance load (see Fig. 4) is explained by a decrease in the current consumed by the amplifier (see Fig. 5), which leads to the operating point falling into the cutoff region when it moves along the load line, and distortion of the amplified signal.

When working on an inconsistent high-resistance load 14, the control signal in the prototype circuit increases in proportion to the increase in load resistance, which leads to an increase in current consumption (see Fig. 5, curve 3). Since in this case the load line is more gentle than in the case of working on a standard load, the efficiency of the amplifier element decreases, while increasing the power dissipated on it. This may result in failure of the amplifier element.

In the inventive wideband power amplifier with automatic adjustment of the current consumption when working on an inconsistent high-resistance load, the current consumed by the amplifier is reduced (see Fig. 5, curve 1), reducing the power dissipated on the amplifier element.

Thus, the positive effect of the utility model is: 1 to increase the efficiency when working on an inconsistent high resistance load; 2 in eliminating distortions of the amplified signal when working on an inconsistent low-impedance load, while increasing the level of output power given to this load; 3 in providing idle load protection.

Due to the combination of newly introduced features, the proposed broadband power amplifier with automatic adjustment of the current consumption, for example, on the KT909A transistor in comparison with the known device based on experimental studies has:

- 2.6 times greater efficiency when working on an inconsistent high resistance load;

-does not distort the amplified signal when working on an inconsistent low-resistance load, while at the same time increasing the level of output power given to this load by 5.5 times;

- provides a reduction in the current consumed by the amplifier during operation at an inconsistent high-resistance load, which eliminates the possibility of the operating point entering the region of unacceptable voltages.

1.Oksner E.S. Powerful field effect transistors and their application. : Per. from English - M .: Radio and communications. 1985 .-- 288 p.

2.Titov A.A. Compensation of the effect of the detector effect in an amplifier with automatic adjustment of current consumption // Radio engineering. 1987. No. 8. S. 10-13.

3.Kuznetsov V.D., Ablin N.B. Directional coupler for collective television reception systems. - A.S. USSR No. 202252, cl. . “Bulletin of inventions. 1967.No 19.

4. Titov A.A., Ilyushenko V.N., Avdochenko B.I., Obikhvostov V.D. Broadband power amplifier to work on an inconsistent load // Instruments and experimental equipment. 1996. No. 2. P. 68-69.

5. Broadband radio transmitting devices / Ed. O.V. Alekseeva. - M .: Communication. 1978.- 304 S.

6.Titov A.A. The increase in the output power of transistor amplifiers in mode A // Radio engineering. 1985. 3.P. 81-83.

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LITERATURE

Claims (1)

A broadband power amplifier with automatic adjustment of the current consumption, containing the first amplifier element, the common electrode of which is connected to the common bus, the input electrode is connected to the signal source through the input correction circuit, the output electrode is connected to the input of the output correction circuit and through the serial connection of the inductor and the first resistor - with a power source, and the connection point of the inductor and the first resistor through the first capacitor is connected to a common bus, a detector, the input of which is connected n with the first output of the second capacitor and through the initial bias circuit to the power source, and the output is connected to the input electrode of the second amplifier element, the common electrode of which is connected to the connection point of the inductor and the first resistor, and the output electrode is connected through the second resistor to the input electrode of the first amplifier element, characterized in that a directional coupler of the incident wave and a corrector are inserted into it, the input of the directional coupler is connected to the output of the output correction circuit, the output to the load minutes, branch power output - to an input of the equalizer and the ballast output - with a ballast load output equalizer connected to the second terminal of the second capacitor.