RU2536673C1 - Power control system - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: device consists of a pre-output amplifier 1, a first 2 and a second 3 switch, a non-attenuated channel 4 and an attenuated channel 5. The input of the pre-output amplifier 1 is designed to be connected to a signal source, and the output is connected to the input of the first switch 2. The first output of the first switch 2 is connected to the input of the non-attenuated channel 4 and the second output is connected to the input of the attenuated channel 5. The first input of the second switch 3 is connected to the output of the non-attenuated channel 4 and the second input is connected to the attenuated channel 5. The non-attenuated channel 4 comprises series-connected switch 6 and output amplifier 7. The attenuated channel 5 comprises series-connected correcting attenuator 8 and pre-output variable attenuator 9.

EFFECT: wider range of controlling output signal power owing to use of double-channel power control system.

3 cl, 2 dwg

Description

The invention relates to electronics, in particular to attenuator devices, and can be used as a device for adjusting the output signal power.

When designing electronic equipment, in some cases it is necessary to ensure the attenuation of its output power in a wide range - from 0 dB to minus 130-150 dB.

Known power control systems [patent application US No.2011316645. certificate na utility model RU No. 11394, US patent No. 5347239], which is a step attenuator and containing a number of attenuator links connected in series through switches. The switching on and off of some of them is carried out by means of, for example, a programmable control unit, thus obtaining the necessary attenuation of the output signal power. The arrangement of the cascade connection of the attenuator links after the output amplifier operating in saturation mode allows to achieve the minimum unevenness of the transmission coefficient in the working frequency band and the best thermal stability.

However, the need to compensate for the significant initial attenuation of broadband variable electronic microwave attenuators (especially when implementing power adjustments with great depth) requires a significant increase in the power of the output amplifier stage. The use of increased power element base in the design of microwave amplifiers entails its rise in price and decrease in efficiency. Correct operation of the power control system located at the input of the amplifier is possible when it is operating in linear mode, which requires the introduction of additional thermal stabilization schemes and equalization of the amplitude-frequency characteristic (AFC). Cascading the attenuators also leads to a deterioration of the initial frequency response of the amplifier in the mode with minimal insertion attenuation.

The closest analogue of the claimed invention is a two-channel power control system [US patent No. 7457593], in which one channel passes the signal without attenuation, without affecting its parameters, and the second contains a variable electronic attenuator, providing the required attenuation. Switching between channels is carried out using two mechanical switches at the input and output channels. So, if signal attenuation is not required, the switches close in the position in which the signal passes through the channel without attenuation. Otherwise, the switches switch to another position in which the signal is fed to a variable attenuator, providing the required attenuation of the output signal.

However, despite all the advantages of this scheme, its application does not provide the required level of attenuation. The maximum attenuation in accordance with the patent description is minus 125 dB in the frequency range from 100 kHz to 3 GHz.

The task of the invention is to expand the range of adjustment of the output signal power.

The essence of the claimed invention lies in the fact that the power control system comprising a channel with attenuation, a channel without attenuation, first and second switches, a pre-output variable attenuator connected in series with a channel with attenuation, while the first output of the first switch has one input and two outputs and the first input of the second switch having two inputs and one output are connected respectively to the input and output of the channel without attenuation, the second output of the first switch and the second input of the second switch are connected correspondingly, with the input and output of the channel with the attenuation, it additionally contains: a pre-output amplifier connected to the input of the first switch, a switch and an output amplifier connected in series to the channel without attenuation, a correcting attenuator connected in series with the pre-output variable attenuator.

In addition, the claimed system, which along with the above features further comprises an output variable attenuator connected to the output of the second switch.

In addition, a system is claimed in which, along with the above features, the first and second switches are made electronic.

The technical result of the claimed invention is to expand the range of attenuation of the output power with a depth of minus 130-150 dB due to the use of a two-channel power control system. This depth of power attenuation can be achieved by a high isolation of channels provided by a combination of a switch and an output amplifier in the channel without attenuation and a pre-output amplifier. At the same time, another important difference from the closest analogue, which minimizes insertion loss, is the use of two amplifiers, one of which is of lower power and is connected to the input of the first switch, the other is of higher power and is included in the channel without attenuation. Such a scheme allows not to take into account losses in the first switch and reduce the requirements for amplifiers, namely, it allows to abandon high power amplifiers due to minimizing channel losses without attenuation at the required zero attenuation of broadband attenuators, which significantly reduces the cost of the device. The combination of switching the corrective and output attenuators in the channel with the attenuation together with the switch and the output amplifier in the channel without attenuation provides the best frequency response and high thermal stability in the entire attenuation range due to the absence of an extended control path and the saturation of output power for the output and output amplifiers.

The invention is illustrated using Fig.1, 2, which depict:

Figure 1 - block diagram of the inventive power control system;

Figure 2 is a block diagram of the inventive power control system with an output variable attenuator.

In figure 1, 2 positions 1-10 are indicated:

1 - pre-output amplifier;

2 - the first switch;

3 - the second switch;

4 - channel without attenuation;

5 - channel with attenuation;

6 - switch;

7 - output amplifier;

8 - corrective attenuator;

9 - pre-output variable attenuator;

10 - output variable attenuator.

The power control system consists of a pre-output amplifier 1, first 2 and second 3 switches, a channel without attenuation 4, a channel with attenuation 5. The input of the pre-output amplifier 1 is for connecting to a signal source, and the output is connected to the input of the first switch 2, made with one input and two exits. The first output of the first switch 2 is connected to the input of the channel without attenuation 4, the second to the input of the channel with attenuation 5. The second switch 3 is made with two inputs and one output. The first input of the second switch 3 is connected to the output of the channel without attenuation 4, the second input to the channel with attenuation 5. The channel without attenuation 4 contains a series-connected switch 6 and output amplifier 7. The channel with attenuation 5 contains sequentially connected correction attenuator 8 and a pre-output variable attenuator 9.

In the particular case of the invention, the power control system may further comprise an output variable attenuator 10 connected to the output of the second switch 3.

The power control system operates as follows.

The microwave signal is fed to the input of the pre-output amplifier 1 and then, depending on the required attenuation value, either to the channel without attenuation 4 or to the channel with attenuation 5. To obtain the maximum power value at the output of the device, the signal enters the channel without attenuation 4. For this the first 2 and second 3 switches are closed in position I. In this case, the switch 6 remains open, and the signal is fed to the output amplifier 7.

To attenuate the output signal, the first 2 and second 3 switches switch to position II. In this case, the signal from the second input of the first switch 2 goes to the correcting attenuator 8. The level of leaking power from the channel without attenuation 4 to the output of the entire device and to the channel with attenuation 5 through the second switch 3 in position II should be significantly less than the maximum possible attenuation variable output attenuator 9. This condition is provided not only by the attenuation of the second switch 3 in the locked state, but also by the attenuation of the locked switch 6 and the output amplifier 7 with the power off.

Corrective attenuator 8 is used to equalize power when switching between channels without attenuation 4 and attenuation 5, providing smooth, without interruption, adjustment of the output signal power. The attenuation value of the correcting attenuator 8 is determined by the formula:

, $$L_{{\mathrm{BUT}}_{\mathrm{TO}}}=\frac{P_{\mathrm{At}\mathrm{AT}}}{P_{\mathrm{At}R}}\cdot \frac{\mathrm{one}}{L_{\mathrm{TO}\mathrm{about}}\cdot L_{{\mathrm{BUT}}_{P0}}}$$

,

where P _SW - the power of the output amplifier 7,

R _UR - power pre-output amplifier 1,

L _Ko - attenuation of the second switch 3 in the open state,

- начальное затухание предвыходного переменного аттенюатора 9. $$L_{A_{P0}}$$

- the initial attenuation of the output variable attenuator 9.

The decrease in the level of output power is performed by changing the introduced attenuation by the pre-output variable attenuator 9 to its maximum value.

In the particular case of the invention, when there is no requirement for high output power, the output of the second switch 3 may include an output variable attenuator 10, providing an additional extension of the range of adjustment of the power of the output signal by increasing the depth of attenuation. The power leaking from the channel without attenuation 4 in this case is supplied to the input of the output variable attenuator 10 and does not limit its maximum insertion attenuation. In this case, the attenuation adjustment occurs in a similar way with the only feature that the attenuation introduced by the output variable attenuator 10 is first changed to a maximum. When using a channel with attenuation 5, the introduced attenuation of the output variable attenuator 10 is set to minimum and the first 2 and second 3 electronic switches are closed in position II. The attenuation value of the correcting attenuator 8 in the case of using the output variable attenuator 10 is determined by the formula:

, $$L_{{\mathrm{BUT}}_{\mathrm{TO}}}=\frac{P_{\mathrm{At}\mathrm{AT}}}{P_{\mathrm{At}R}}\cdot \frac{L_{{\mathrm{BUT}}_{\mathrm{AT}}\max }}{L_{\mathrm{TO}\mathrm{about}}\cdot L_{{\mathrm{BUT}}_{P0}}}$$

,

where P _SW - the power of the output amplifier 7,

R _UR - power pre-output amplifier 1,

L _Ko - attenuation of the second switch 3 in the open state,

- начальное затухание предвыходного переменного аттенюатора 9, $$L_{A_{P0}}$$

- the initial attenuation of the output variable attenuator 9,

- максимальное затухание выходного переменного аттенюатора 10. $$L_{A_{\mathrm{AT}}\max }$$

- maximum attenuation of the output variable attenuator 10.

где $$L_{A_{П}\max }$$

- максимальное вносимое затухание предвыходного переменного аттенюатора 9, $$L_{A_{В}\max }$$

- максимальное вносимое затухание выходного переменного аттенюатора 10.Then, an increase in the attenuation of the output signal is achieved by increasing the value of the introduced attenuation by the output variable attenuator 9 to the maximum value with the minimum attenuation introduced by the output variable attenuator 10. Further reduction of the level of output power is carried out by increasing the attenuation introduced by the output variable attenuator 10 to the maximum value . Adjusting the power of the output signal using the output variable attenuator 10 is in the range from 0 dB to $$\left(L_{A_P\max }+2\cdot L_{A_{\mathrm{AT}}\max }\right),$$

 Where $$L_{A_P\max }$$

- maximum insertion attenuation of the preoutput attenuator 9, $$L_{A_{\mathrm{AT}}\max }$$

- maximum insertion attenuation of the output variable attenuator 10.

In the case of the use of electronic switches, the claimed invention can be used in miniature amplifier modules, providing high speed adjustment of the output signal power and significantly reducing the dimensions of the device compared to devices that use mechanical switches.

The possibility of adjusting the power level of a microwave amplifier using the two-channel method was experimentally confirmed when creating a multi-channel broadband splitter of centimeter wavelength signals with a large depth of output level adjustment developed at the applicant enterprise.

Attenuators are made using an executive microcircuit of the same type, providing an input attenuation from 0 to minus 32 dB with a step of 1 dB and an initial attenuation of minus 5 dB. The output and pre-output variable attenuators contain two of the aforementioned microcircuits. In connection with the specified technical requirements, the low output power of the amplifier (less than 10 mW), it was possible to place two microcircuits after the second switch. The corrective attenuator is structurally made in the form of a set of resistive T-shaped attenuators. Each of the nodes of the switches and the circuit breaker provides channel locking without attenuation of more than 45 dB with an initial loss of less than 1.7 dB.

Using the inventive circuit allows you to maintain a balance between the use of inexpensive electronic components and high characteristics of the device.

Claims (3)

1. Power control system comprising a channel with attenuation, a channel without attenuation, first and second switches, a pre-output variable attenuator, sequentially connected to a channel with attenuation, the first output of the first switch having one input and two outputs, and the first input of the second switch having two inputs and one output are connected respectively to the input and output of the channel without attenuation, the second output of the first switch and the second input of the second switch are connected respectively to the input and output of the channel with attenuation, ex characterized in that it further comprises a pre-output amplifier connected to the input of the first switch, a switch and an output amplifier connected in series to the channel without attenuation, a correcting attenuator connected in series with the pre-output variable attenuator. 2. The system according to claim 1, characterized in that it further comprises an output variable attenuator connected to the output of the second switch. 3. The system according to claim 1, characterized in that the first and second switches are made electronic.

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