Negative pressure protection circuit

Abstract

The present invention relates to a negative voltage protection circuit. On the one hand, the leakage voltage control module disconnects the conductive path between the drain power supply and the drain of the power amplifier tube according to the first voltage, the second voltage and the drain switch signal, so that through the first The first voltage, the second voltage and the drain switch signal can realize the timely disconnection of the drain voltage; on the other hand, when the received second voltage becomes 0V, the voltage buffer module reduces the voltage change of the output sixth voltage rate, and finally the drain of the power amplifier tube is powered off and the time required for the drain voltage drop to 0 is much shorter than the time required for the sixth voltage drop of the power amplifier tube grid to be 0, that is, the drain of the power amplifier tube is powered off to the drain During the period when the voltage becomes 0, the sixth voltage only changes by a small amount, and the grid voltage is always under the safe negative voltage protection, so as to realize the protection of the power amplifier tube.

Description

Technical field [0001] The present invention relates to power amplifier control technology, particularly to a negative pressure protection circuit. Background technique [0002] 5G communication based on the requirements, increasing the frequency band of the base station amplifiers, but generally the higher the frequency of the power tube, the lower the efficiency, the number of channels is generally 5G base channel more than 4, even more than 64 channels can be achieved. Based on the requirements of increasingly high frequency power transistor, a conventional power transistor can not meet the requirements of high efficiency, so more and more of the base station amplifier power amplifier using GaN. GaN efficiency power amplifier efficiency compared to conventional LDMOS tube high, but if GaN power amplifier drain voltage is turned on at the gate of protection no negative case, it will burn in an instant. It is necessary to design a reliable circuit protection negative pressure, i...

AI Technical Summary

Problems solved by technology

[0003] However, in this process, the gate voltage loses the required negative voltage protection first, and then the conditional switch turns off the leakage voltage. Generally, there is a filter capacitor with a large capacitance at the leakage voltage, and it takes a long time for the leakage voltage to drop from being turned off to zero. for a long time, see for example Figure 5 , the drain of the power amplifier tube is powered off at t1, but the drain voltage is completely reduced to 0V at t2, and the time difference between t1 and t2 is 10ms, and the power amplifier tube may still be burned out

In order to solve this problem, a discharge circuit is added to the leakage voltage to speed up the discharge speed after the drain is closed. This not only increases the complexity of the circuit, but also reduces the reliability of the circuit. When the negative pressure is pulled down instantly, the power amplifier tube may still be burnt out

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