JPH01147708A - Power amplifier - Google Patents

Abstract

PURPOSE:To attain a safe operation without arriving at element destruction even when the change in the lapse of time of an input impedance occurs by obtaining the supplying current of installed plural amplifying elements, namely the load balance of the amplifying elements at any time. CONSTITUTION:To the input side of the plural amplifying elements, namely a transistor (TR) 1, an input matching circuit 2 variably controlled by a motor 8 is connected. On the other hand, a power is fed from a power source 9 to the TR 1, a current detector 5 is inserted between the power source 9 and the TR 1, each collector current of the TR 1 is detected, inputted to a control circuit 19, and the motor 8 is driven. Based on this, when any of the input impedance changes among the plural TRs 1, the collector current also changes, the changed portion is detected by a detector 5, and the circuit 2 is adjusted by the motor 8. Consequently, when the change in the lapse of time of the input impedance of the TR 1 occurs, the element does not arrive at destruction, and the safe operation is attained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to power amplifiers.

[Conventional technology]

Conventionally, fixed impedance elements were used in the input/output matching circuit, and multiple transistors were operated in parallel as shown in the m4 diagram. It was a push-pull circuit.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, a) When operating a plurality of amplifying elements, if the characteristics of the elements are not made the same, there may be a phenomenon in which the burden power is concentrated in the elements, leading to destruction of the elements.

b) When the input impedance of an amplifying element changes over time, power stress is applied to the element, which further changes the input impedance, creating a vicious cycle that eventually leads to the destruction of the transistor.

There is a problem. The present invention is intended to solve these problems, and its purpose is to eliminate changes in human impedance over time even if the characteristics of the elements are unbalanced when multiple amplifying elements are operated. The object of the present invention is to provide a power amplifier that enables safe operation without destroying the elements.

[Means for solving problems]

The power amplifier of the present invention is equipped with two input matching circuits in which a variable impedance element is coupled to the human power of one amplifying element and an eight motor shaft, and a power supply section of one amplifying element is connected to a five
Equipped with a current detector. A plurality of amplifier circuits having the above-mentioned equipment are combined, and the output of the current detector No. 5 is inputted to the current/voltage converter No. 13, respectively, and the output is converted to one.
4 voltage comparators compare each, drive 8 motors according to their outputs, and change the constants of 2 input matching circuits to balance the supply currents of multiple 1 amplification elements. is characterized by.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention,
This is an example in which a transistor is used as an amplification element. Indicates parallel operation. In this figure, two input matching circuits are connected to the input side of one plurality of transistors, which are variable-controlled by eight seven-stage impedance elements and are mounted on impedance elements. - On the other hand, power is supplied to each run sister from the power supply 9, and a current detector 5 is inserted between this power supply and the transistor to detect the individual collector current of the plurality of transistors, and the control of 19 is performed. It is input to the circuit and drives 8 motors. Furthermore, the output connection circuit 4 is in charge of impedance matching between the output end impedance of E and the transistors connected in parallel. Now, FIG. 2 is a block diagram of the 19 control circuits in FIG. 1. In both figures, if the input impedance of one of the plurality of connected transistors changes, the collector current will inevitably change.

This change is detected by the current detector 5, the current is converted to voltage by the current voltage converter 13, and this output is
The outputs of the multiple 13 current-voltage converters are input to the voltage comparator No. 4, and the outputs of the multiple 13 current-voltage converters are compared and operated. The motor driver No. 15 is used to drive the motor No. 8, and the collector of each transistor is Continue adjusting the manual matching circuit with 8 motors until the currents match. Also, even if the characteristics of multiple transistors connected in parallel are unbalanced, the motor 8 will operate as described above until the output of the current detector 5, that is, the collector current of each individual transistor 1, match. Continue adjusting the 20-input matching circuit. In other words, if the above invention is implemented in parallel operation of amplifying elements, there is no need to deliberately align the characteristics of the elements, and even if the input impedance of the elements changes over time, the elements will not be destroyed. Enables safe driving without causing any damage.

Further, FIG. 3 shows an example in which VARICO/ is used as the variable impedance element of the input matching circuit of FIG. 1.

〔Effect of the invention〕

According to the above-mentioned invention, by constantly balancing the supply current of the plurality of amplifying elements installed, that is, the load balance of the amplifying elements, the input impedance changes over time even if the characteristics of the elements are unbalanced. Even if there is a change, the device does not break down and safe driving is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention,
2 is a block diagram of the 19 control circuits in FIG. 1, and FIG. 3 is a circuit diagram using a variable capacitor as an example of the variable impedance element of the input matching circuit in FIG. FIG. 4 is a block diagram of the conventional method. 1...Amplifying element 2...Input matching circuit 3...Coupling capacitor 4...Output matching circuit 5...Current detector 6...High frequency check 7...Coil 8...Motor 9...Power source 10...Bias circuit 11.12...Capacitor l3...Current voltage converter 14...Voltage comparator 15...Motor driver 16.17...Coil 18...・Variable capacitor 19...control circuit or above

Claims (1)

[Claims] Equipped with 2 input matching circuits, which connect variable impedance elements to the 8 motor shafts, to the input of the 1 amplification element,
The power supply section of the amplifier element 1 is equipped with the current detector 5, and a plurality of amplifier circuits having the above-mentioned equipment are combined.
The outputs of the current detectors are input to 13 current/voltage converters, and the outputs are compared by 14 voltage comparators, and 8 motors are driven according to the outputs. A power amplifier characterized in that the constants of an input matching circuit are changed to balance supply currents of a plurality of amplifying elements.