SU1427578A1 - Radio transmitter - Google Patents

Abstract

The invention relates to radio engineering and can be used to generate transmitted signals with the addition of power. The purpose of the invention is to increase reliability by protecting against overloads, transistors of a block of N transistor power u-lees. The radio transmitter contains exciter 1, controlled attenuator 2, unit 3 transistor power u, directional coupler 4, load 4, differential voltage 7, amp 1tud detector 8, low pass filter (LPF) 9, controlled voltage divider ( UDN) 13, L elements of comparison 14-, L sources 15 of the reference voltage. To achieve the goal, an exciter power level sensor 6, control key 10, LPF 11, UDN 12 are entered into the radio transmitter. In the proposed device, the nominal operating mode of the healthy transistor power level of the 3 E unit is established, and overloads in the transient state are excluded. mode. 2 Il.

Description

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The invention relates to radio engineering and can be used to form transmitted signals with power addition.

The purpose of the invention is to increase reliability by protecting the transistors of the N transistor power amplifiers from overloading the transistors.

Figure 1 shows the structural electrical circuit of the proposed radio transmitter; Fig. 2 shows an exemplary embodiment of the first and second controlled voltage dividers.

The radio transmitter contains exciter 1, controlled attenuator 2, block 3 N transistor power amplifiers, directional coupler 4 load 5, exciter power level sensor 6, differential amplifier 7, amplitude detector 8, first low-pass filter 9 (LPF), control key 10 , the second low-pass filter 11 (LPF), the second controlled voltage divider 12, the first controlled voltage divider 13, L elements of comparison 14, 142, ..., 14ts, L sources 15, 15, ..., 15 reference pressure.

The first and second controllable voltage dividers 13 (12) contain a resistor 16, L (N) switching resistors 17 ,, (n adjustable resistor 18, L (N) of transistors 19,, 19;, ..., 19 (s) source 20 constant voltage.

The radio works as follows.

The controlled attenuator 2 is designed so that when the signal on the inverting input of the differential amplifier 7 is increased, the attenuation of the controlled attenuator 2 increases, and on the increase in the signal on the non-inverting during the differential amplifier 7.

Unit 3 N transistor power amplifiers contains N transistor power amplifiers, which are interconnected according to the power addition scheme (for example, on-between the corresponding outputs and inputs of bridge dividers and power adders). Each of the N transistor power amplifiers is equipped with a sensor characterizing the state of the transistor power amplifier (faulty). The sensor can be performed, for example, in the form of a resistor.

which is connected between the common bus and the corresponding output of the emitter circuit of the transistor. The constant voltages produced by these resistors are fed to the outputs of the control signals, block 3.

In the initial state (the high-frequency signal at the output of the exciter 0 .1 is absent, the supply voltage is supplied to the radio transmitter) the output power of unit 3, the voltage across N its control signal outputs and the voltage at output of sensor 6 and the amplitude of detector 5 are zero. Controlled attenuator 2 has a maximum attenuation. At the same time, the output voltage of the second controlled divider 12 voltage is maximum 0 (transistors 9, 9.19fj are closed) and should exceed any of the reference voltages of L. sources 15, 152, ..., 15, fed to the first inputs of the corresponding elements compared to 5, neither 14,, 14, ..., 14 ,. In this case, the output voltages of the elements of comparison 14,, 14, .- .., 14ts, made, for example, in the form of voltage comparators, correspond to level 1.

All L transistors of the controlled voltage divider 13 are in a closed state and the voltage at its output E is determined by the output voltage.

E, P.N (1-L / N) .K4j ,, (1) 5 where R. is the nominal output power of one of the N transistor power amplifiers, unit 3;

transmission coefficient of a circuit made of a serially connected directional coupler 4, an amplitude detector 8 and a low-pass filter 9:

The previously accepted maximum permissible number of transistor power amplifiers of unit 3 that can fail.

When a signal is received from the exciter 1 at the output of the sensor 6, a voltage appears at the control input of the switch 10, which is activated and connects the output of the controlled 5 voltage divider 13 to the input of the low-pass filter 11. The voltage at the output of the low-pass filter 11 begins to increase smoothly with a constant time Tj up to the value E.

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the voltage at the control input of the controlled attenuator 2, to which it is supplied from the output of the low-pass filter 11 through the differential amplifier 7.i

The attenuation of the controlled attenuator 2 is smoothly reduced, and the high-frequency signal at the input and, accordingly, at the output of block 3 is also smoothly without

and disconnect the corresponding L resistors 17 connected in parallel with the adjustable resistor .IS. The voltage at the output of the controlled voltage divider 13 increases abruptly and becomes equal to N (1-K / N) K

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with OfeKiL. At the same time, the voltage at the output of the low-pass filter 11 gradually increases the emission at, where. - constant n to the value of E and the output level at the time of the low-pass filter 9, increases and the power stabilizes at the level of mitts to the value of Pb, (1- L / N) 2, where PW is the output power of unit 3, where (NK) of serviceable transistor power amplifiers of unit 3, where K is the number of failed transistor power amplifiers of unit 3, the corresponding control signal outputs of unit 3 arrive and the control signal voltages also increase smoothly. These voltages are applied to the inputs of the respective transistors 19 of the N transistors of the controlled voltage divider 12. At a certain point in time, these transistors open. Parallel to the adjustable resistor 18 of the controlled voltage divider 12 are connected respectively (N-K) corresponding resistors of N resistors 17 and the voltage at the output of the controlled voltage divider 12; decreases. The smaller K is the number of failed transistor power amplifiers, the lower the voltage at the output of the controlled voltage divider 12 and, accordingly, the lower the voltage at the second inputs of the comparison elements 14, 14, ..., 14t ,.

In the case when all transistor power amplifiers of unit 3 are in good condition (), the output voltage of the controlled divider 12 voltage must be lower than any of the reference voltages of the sources of the reference voltages 15,, 15, ..., 15.

When the number of failed 3K transistor power amplifiers is less than the maximum allowable number of their L, the voltage at the second inputs (L-K) of the L elements of comparison 14 becomes lower than the reference voltages supplied to their first inputs from the sources 15, 15,. .., 15. At this voltage, the outputs (L-K) of the L elements of the comparison 14,, Hj, ..., 14j correspond to the level (L-K) of the transistors of the L transistors 19 of the controlled divider 13, the voltage is closed

RF, (1-K / N) S corresponding to the number K of failed transistor power amplifiers of unit 3.

Above, the operation of the radio transmitter in the erd switching process was considered, provided that prior to its inclusion it could contain failed transistor power amplifiers, the number of which was OiKtL. In case of failure of the transistor power amplifiers of the unit 3, which occurred during the operation of the radio transmitter, the voltage at the output of the low-pass filter 9 decreases in accordance with the expression

if, (1-K /) - Kdp (2)

The control signals at the outputs of block 3, connected to the failed transistor power amplifiers of block 3, become zero. At the same time, the corresponding number of transistors 19 in the control divider 12 voltage closes to the voltage at its output and, accordingly, at the second inputs of the comparison elements 14 ,, ..., 14j increases and at the outputs of the corresponding comparison elements 14 the voltage becomes pasHEJM 1. In In this case, the corresponding number of transistors -19 in the controlled voltage divider 13 is opened and the voltage at its output decreases in accordance with the expression (1),

Thus, at both inputs of the differential amplifier 7, the signal voltages are reduced by the same amount. At that, it assumes that the transmission coefficient of the sequential circuit containing the controllable key 10 and the second low pass filter 11 is equal to one. Therefore, the voltage at the control input of the controlled attenuator 2 remains unchanged. At the same time, the attenuation of the controlled attenuator 2 remains unchanged, as well as the input power levels of the transistor power amplifiers of the unit 3.

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and disconnect the corresponding of L resistors 17 connected in parallel to the adjustable resistor .IS. The voltage at the output of the controlled voltage divider 13 increases abruptly and becomes equal to N (1-K / N)

with OfeKiL. At the same time, the voltage at the output of the low-pass filter 11 gradually increases to a value of E and the output power level is stabilized at

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with OfeKiL. At the same time, the voltage at the output of the low-pass filter 11 gradually increases to a value of E and the output power level is stabilized at

RF, (1-K / N) S corresponding to the number K of failed transistor power amplifiers of unit 3.

Above, we considered the operation of the radio transmitter in the process of erd switching on, provided that prior to its switching on it could contain failed transistor power amplifiers, the number of which was OiKtL. In case of failure of the transistor power amplifiers of the unit 3, which occurred during the operation of the radio transmitter, the voltage at the output of the low-pass filter 9 decreases in accordance with the expression

if, (1-K /) - Kdp (2)

The control signals at the outputs of block 3, connected to the failed transistor power amplifiers of block 3, become zero. At the same time, the corresponding number of transistors 19 in the control divider 12 voltage closes to the voltage at its output and, accordingly, at the second inputs of the comparison elements 14 ,, ..., 14j increases and at the outputs of the corresponding comparison elements 14 the voltage becomes pasHEJM 1. In In this case, the corresponding number of transistors -19 in the controlled voltage divider 13 is opened and the voltage at its output decreases in accordance with the expression (1),

Thus, at both inputs of the differential amplifier 7, the signal voltages are reduced by the same amount. In this case, it is assumed that the transmission coefficient of the serial circuit containing the controllable key 10 and the second low-pass filter 11 is equal to one. Therefore, the voltage at the control input of the controlled attenuator 2 remains unchanged. At the same time, the attenuation of the controlled attenuator 2 remains unchanged, as well as the input power levels of the transistor power amplifiers of the unit 3.

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Thus, if part of the transistor power amplifiers of the unit 3 fail, the remaining efficient transistor power amplifiers continue to operate in nominal mode. In order to avoid overloading tpaHSHCTOpHMx of power amplifiers of unit 3 in a transient mode if they fail during the operation of the radio transmitter, it is necessary to ensure the condition t,. Considering that it is higher for the mode of turning on the radio transmitter, it is accepted cj E; o, then to avoid overload in both cases the equality must be equal. The absolute values of Cj and C must be such that the rise time of signals at the inputs of the differential amplifier - 7 is determined only by the first 9 and second 11 LPF, “Thus, in the proposed device, the nominal mode of operation of serviceable transistor power amplifiers of unit 3 in the steady-state mode is ensured and overloads in the transient condition are eliminated.

Form, l and inventions

A radio transmitter containing a series-connected exciter, a controlled attenuator and a block of N transistor power amplifiers, a directional coupler, whose input is connected to the output of the sum signal of a block of N transistor power amplifiers, and the output of the main channel

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with a load, a differential amplifier, the output of which is connected to the control input of a controlled attenuator, serially connected amplitude detector, the input of which is connected to the output of the auxiliary channel of the directional coupler, and the first low-pass filter, the output of which is connected to the inverting input of the differential amplifier, L comparison elements , the first input of each of which is connected to the output of the corresponding reference-voltage sources from L, the first controlled-voltage divider, each of the control Auxiliary inputs of which are connected to the output of a corresponding of L comparison elements, characterized in that, in order to increase reliability by protecting the block transistors of the N transistor power amplifiers from overloading, a second controlled voltage divider is introduced, each of the inputs of which is connected to the corresponding of N the outputs of the control signals of the N transistor power amplifier unit, and the output with the second inputs L of the comparison elements, the exciter output and the non-inverting input of the differential amplifier are entered after ovatelno sensor coupled power level of pathogen controlled by a key signal input coupled to an output of the first controllable divider nap of voltage and a second low-pass filter, where (N-1).

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Output

Claims (1)

Claim A radio transmitter containing a series-connected exciter, a controlled attenuator and a block N of transistor power amplifiers, a directional coupler whose input is connected to the output of the total signal of a block N of transistor power amplifiers, and the output of the main channel 1427578 6 with a load, a differential amplifier, the output of which is connected to the control input of the controlled attenuator, a series-connected amplitude detector, the input of which is connected to the output of the auxiliary channel of the directional coupler, and a first low-pass filter, the output of which is connected to the inverting input of the differential amplifier, L comparison elements , the first input of each of which is connected to the output of the corresponding from L reference voltage sources, the first controlled voltage divider, each of the leveling inputs of which is connected to the output of the corresponding comparison elements from L, characterized in that, in order to increase reliability by protecting against overload of the transistors of the block N of transistor power amplifiers, a second controlled voltage divider is introduced, each of the inputs of which is connected to the corresponding of the N outputs of the control signals block N transistor power amplifiers, and the output with the second inputs L of the comparison elements between the output of the pathogen and the non-inverting input of the differential amplifier are entered after been consistent coupled exciter power level detector controllable switch, a signal input coupled to an output of the first managed ^s voltage divider and a second lowpass filter, where 1έά ^ (Ν-1). Control inputs -> "-> -----------—> ------------------ Shie g * ' Exit