RU1803946C - Limiter - Google Patents

Abstract

Usage: in the microwave technology as a protective device of the input paths from accidental interference. SUMMARY OF THE INVENTION: in a limiter comprising a length of transmission line with a parallel-connected restriction diode connected to the comparator, the comparator is made up of a buffer and a comparison unit connected in series, as well as a threshold level selection circuit. 1 ill.

Description

The invention relates to radio engineering, in particular to microwave technology, and may find application as a self-contained device protecting the input paths of microwave receivers from intense random interference.

The purpose of the invention is to increase the reliability of the limiter by increasing its maximum input power due to the additional fixed bias supplied by the comparator to the limit diode.

The drawing shows the electrical circuit of the proposed limiter.

A limiting diode 2 is connected in parallel to the segment of transmission line 1, the first (negative) electrode 3 of which is connected to the device common bus 4 and to the output 5 of the comparator 6. The second electrode 7 of diode 2 is connected to the input 8 of the comparator 6; the input 8 is connected to the inverting input of the decoupling buffer 9, the non-inverting input of which is connected through the first resistor 10 to its inverting input. The output of buffer 9 is connected to a non-inverting input of comparator 11.

The inverting input of the comparison unit 11 is connected to the output of the threshold level generating circuit 12, and the output of the comparing unit 11 through the second resistor 13 is connected to the non-inverting input of the buffer 9. The buffer 9, the comparing unit 11, the second resistor 13 and the threshold level generating circuit 12 together comprise comparator 6. A constant voltage source 14 powers the comparator 6, in particular a threshold level generation circuit 12.

The buffer 9 decouples the input of the comparator 11 from the shunt action of the first resistor 10, which is between 5 and 100 ohms. The output impedance of comparator 11 and the resistance of the second resistor 13 should be as low as possible so as not to impede the passage of the diode current; their total impedance should not exceed the impedance of the first resistor 10 by more than 2 times.

The claimed limiter operates as follows.

In the initial state, the microwave power at the input of the limiter is small, the voltage at the input of the comparator 6 (on the resistor 10) was

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but zero, therefore, the voltage at the output of the comparison unit 11 is equal to zero. Diode 2 is in a high-resistance state, the loss of the limiter is minimal.

As the input power increases, the current rectified by the diode 2 increases, which creates a voltage drop on the first resistor 10. At a threshold value of the input power Pnr, the voltage at the non-inverting input of the comparator 11 reaches the threshold level Unop, and the comparator 11 generates a fixed additional current that lowers the diode impedance to a state close to low resistance, safe for burnout. This leads to an abrupt increase in attenuation in the microwave path. With a further increase in microwave power, the attenuation continues to grow to the maximum possible due to an increase in the current rectified by diode 2.

When the input power decreases, the amount of rectified current decreases, and the voltage at the input of the comparator 6 decreases. When the voltage at the non-inverting input of the comparator 11 is lower than the threshold Unop, the comparator 11 is turned off, the additional current is removed, the attenuation in the path decreases. With a further decrease in the input power, the limiter returns to its initial state, characterized by low losses.

Thus, the comparator. Provides the development of additional fixed

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The bias applied to the limit diode. This allows, at low input power, to transfer the diode to a low-impedance state, which is resistant to fading, to raise the level of maximum allowable power and thereby increase the reliability of the limiter.

Claims (1)

SUMMARY OF THE INVENTION A limiter comprising a length of a transmission line with a parallel limiting diode, a comparator, the output of which is connected to the first electrode of the limit diode and a common bus, and the input is connected to the second electrode of the limit diode, a constant voltage source, characterized in that, with In order to increase reliability by increasing the maximum input power, the comparator consists of a series-connected buffer and a comparison unit, as well as a threshold level selection circuit, while the comparator input pa is connected by the positive electrode of the limiting diode to the inverting input of the buffer, which is connected via a newly introduced first resistor to the non-inverting input of the buffer, the output of which is connected to the non-inverting input of the comparison unit, the output of which through the second resistor is connected to the non-inverting input of the buffer, and the inverting input through the threshold selection circuit level with a constant voltage source.