JPS63131709A - Limiter with recovery time improving circuit - Google Patents

Abstract

PURPOSE:To obtain a quick recovery time of a limiter by impressing a negative bias to a large power limiter diode. CONSTITUTION:In order to quicken the time till a current flowing forward by a large power is zero due to the absence of a large power, a circuit 6 impressing a negative bias forcibly at the point of time of loss of the large power is provided to realize the quick recovery time of the limiter. Since a negative bias is impressed at a point of time of loss of the large power, the carriers in diodes 1, 2 are sucked forcibly by the negative bias to reduce the recovery time. If no negative bias is impressed, since the reduction of natural loss of the carriers in the diodes 1, 2 has to be awaited, the recovery is kept longer.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The purpose of this invention is to improve the recovery time of a high-power diode limiter (hereinafter referred to as a limiter) used in a radar device. It is.

[Conventional technology]

Limiters used in radar devices are configured in various ways depending on the magnitude of RF input power, etc., but generally they are used in the configurations shown in FIGS. 2 and 3. Figures 2 and 3 (Here, a limiter diode (1) for high power is installed on the RF input side, and a limiter diode (2) for low power with a fast recovery time is installed to further reduce the leakage power. A method of attaching the is used.

Next, the operation will be explained. Now, in Figure 3, a detection diode (
A current flows through the limiter diode (1) for high power through 5), and its impedance is extremely low compared to the input/output impedance, and the incoming high power is reflected. Furthermore, although limiter diodes for high power can withstand high power, their recovery time is slow and leakage power is large. In order to further remove this leakage power, a limiter diode (for low power use with fast glue recovery time) was installed.
2).

For small power, no current flows through the detection diode (5), the limiter diode (1) for high power, and the limiter diode (2) for low power, so the diodes Q) and (2) have very high It becomes an impedance and comes out on the output side.

[Problem that the invention seeks to solve]

As described above, large power is turned off and reflected, and small power is turned on and transmitted. Even when power is supplied, it does not turn on immediately and requires a certain amount of time (recovery time) (see Figure 4).
1), (2)). This is mostly determined by the characteristics of the limiter diode for large power in (1), but as mentioned earlier, it is difficult to speed up the recovery time of the limiter diode for large power due to its characteristics. It was determined by the characteristics of the diode in its zero bias state.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a high-power limiter with a fast recovery time.

[Means for solving problems]

The limiter in this invention forcibly applies a negative bias when the current flowing in the forward direction due to the large power stops flowing in the forward direction in order to speed up the time until the current reaches zero. By providing a circuit for applying the voltage, a fast limiter recovery time can be realized.

[Effect]

In the present invention, since a negative bias is applied when the large power is exhausted, the carriers in the diode are forcibly sucked out by the negative bias, so that the recovery time is shortened. If a negative bias is not applied, the recovery time becomes longer because it is necessary to wait until the carriers in the diode decrease due to natural extinction.

〔Example〕

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

In Figure 1, (1) is a high power limiter diode,
(2) is a limiter diode for small power, (3) is a choke coil for DC return, (4) a-c is a capacitor for DC cut, (5) is a detection diode for current coupling, (
6) This shows an example of a circuit for improving beam recovery time, (6) a is a switching transistor, (
6) b is the pv original current limiting resistance.

Now, when an RF multiplied signal with amplitude modulation as shown in Figure 4 (1) is input to the RF input, when the RF ratio output is high, the limiter diode in Figure 1 (1) and (2) It is reflected and output with almost no loss when the power is low, resulting in an RF ratio output as shown in FIG. 4 (2).

100% after high power disappears in Figure 4 (2)
As mentioned above, the time until small power is obtained (recovery time) depends on the performance of the high power limiter diode (1) in FIG.

If there is no circuit (6) at point A in Figure 1 (that is, the same as the conventional circuit at point A in Figure 3), the voltage (or current) waveform will be as shown in Figure 4 (3). Even if the large signal disappears, the voltage (current) does not immediately go to zero, but takes some time.

This time F is a factor that determines the ivy glue coverage time. (Conventional recovery time solid line part in Fig. 4 (2)) Now, by providing the circuit shown in Fig. 1 (6), the voltage waveform at point A in Fig. The adhesive recovery time shown in FIG. 1 (1) becomes much faster than that at zero bias, and the adhesive recovery time as a limiter is improved as shown by the broken line in FIG. 4 (2).

〔Effect of the invention〕

As described above, according to the present invention, since a negative bias is applied to the high power limiter diode, it is possible to obtain a limiter with a fast recovery time.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a limiter with a circuit for improving coverage time according to an embodiment of the present invention, FIGS. 2 and 8 are block diagrams showing conventional limiters, and FIG. 4 is a circuit diagram of a limiter with a circuit for improving coverage time according to an embodiment of the present invention. FIG. 3 is a waveform chart showing recovery time. In the figure, (1) is a limiter diode for high power, (2) is a limiter diode for low power, and (3) is a choke coil for DC return. (4) a to C are DC cut capacitors,
(5) is a detection diode for current supply, (6) is a circuit for improving recovery time, (6) a is a switching transistor, and (6) b is a negative current limiting resistor. In the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A limiter with a circuit for improving recovery time, which is a diode limiter for high power, and is equipped with a circuit that forcibly applies a negative power supply when high power is exhausted in order to speed up the recovery time.