JP2907875B2 - Level control type pulse modulator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse modulator for a continuous high-frequency or ultra-high-frequency signal (RF signal), and in particular, controls the signal level of a pulse-modulated signal via a feedback system. To a pulse modulation device.

b. Problems to be solved by the prior art and the invention Conventionally, this type of pulse modulator did not have a feedback system itself, so that the modulation output level was not affected by external factors such as power supply voltage fluctuation and ambient temperature change. Fluctuate,
There was a problem that the operation was unstable.

Further, even if the pulse modulator is provided with a feedback system, there is a problem that the modulation signal level fluctuates for other reasons and the rising of the pulse modulation wave is extremely slow.

For this reason, the pulse modulator cannot be used in a device for supplying a stable voltage or power, for example, for exciting a laser oscillator or for heating plasma.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to solve the above-described problems, to control the level of a pulse modulation signal of a continuous high or ultra-high frequency signal to be constant, and to increase the level of the rising edge of a pulse modulation wave. An object of the present invention is to provide a controlled pulse modulation device.

c. Means for Solving the Problems In the configuration of the present invention for achieving the object, a continuous high-frequency or ultra-high-frequency signal is modulated by a pulse signal, and the output level is controlled by voltage-controlled attenuating means. In the pulse modulation device, a directional coupler that branches a part of the output pulse modulation signal, a detection circuit that demodulates the pulse modulation signal that is branched by the directional coupler, A sample-and-hold control circuit that generates a sample-and-hold gate signal at a timing, receives a sample-and-hold gate signal from the sample-and-hold control circuit, and converts a pulse signal demodulated by the detection circuit into a DC signal at the timing of the pulse signal. A sample-and-hold circuit for extracting a sampled analog signal value and holding it as a sample; And a differential amplifier circuit for comparing the analog signal held in the path with a level reference signal and outputting the difference voltage to the voltage control attenuating means, and keeping the voltage level of the output pulse modulation signal constant. It is a level control type pulse modulator for controlling.

d. Function The present invention is configured as described above, feeds back a part of the output pulse modulation signal, outputs the pulse signal as a DC signal in a sample and hold circuit unit, and outputs a differential amplifier circuit. The unit compares the signal with a reference signal set as a predetermined level, and voltage-amplifies the difference signal.

This voltage is applied to a voltage-controlled attenuator connected to the pulse modulation circuit to automatically adjust the attenuation and control the level of the pulse modulation signal to a set value.

By converting the input signal of the differential amplifier circuit into a direct current, oscillation and ringing of a pulse signal having a fast rise time are prevented.

e. Embodiment Hereinafter, a preferred embodiment of the present invention will be illustratively described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a level control type pulse modulation apparatus according to the present invention, showing a case of power level control of a pulse modulation signal.

In the figure, a signal having a continuous frequency, for example, 13.56 MHz and 1 W is input to an input terminal 1 of the apparatus. This signal is attenuated by the attenuator 2 and pulse-modulated by the pulse modulation circuit 3 by a gate control signal (pulse signal) that has passed through the photo-isolator 5 from the terminal 4.

The attenuation of the pulse modulated signal is adjusted by a control voltage to be described later in a voltage-controlled attenuator 6, the signal level is controlled, and transmitted to an amplifier circuit 7. This voltage controlled attenuator 6
Is the so-called double balanced mixer
r), and the amount of attenuation is adjusted by the applied voltage. After the maximum output is determined by the variable attenuator 8, the pulse modulated signal that has passed through the amplifier circuit 7 is output from the output terminal 12 through the two-stage amplifier circuits 9 and 10 and the reduction wave (15 MHz) 11. . The output pulse modulated signal is power-amplified by an external amplifier (not shown) and supplied to a load.

At that time, a part of the output is branched by a directional coupler (not shown) and input to the feedback input terminal 16 of the device. This input signal is attenuated by the attenuator 17, detected by the detection circuit 18, and demodulated into the pulse signal. This pulse signal is input to the sample and hold circuit 19 and becomes a DC converted analog signal. On the other hand, the sample-and-hold circuit 19 receives a gate control signal (pulse signal) as a sample-and-hold gate signal at a timing matching the pulse signal applied to the pulse modulation circuit 3 from the terminal 4 via the photo-isolator 5 and the sample-and-hold control circuit 20. ), The pulse signal from the detection circuit 18 is
It is extracted as a DC analog signal value (voltage), held, and output to the arithmetic circuit 21 at the next stage.

The arithmetic circuit 21 is a squaring circuit, and the control target is an arithmetic circuit for the power level of the pulse modulation signal. The output from the arithmetic circuit 21 is applied to one input terminal of a differential amplifier circuit 22 and compared with a reference signal applied to the other input terminal. The reference signal is a level signal set as a reference level, and is a DC voltage signal applied from the terminal 23 via the isolation amplifier 24. The differential amplifier circuit
22 amplifies the difference signal between the output signal from the arithmetic circuit 21 and the set level reference signal, applies the output voltage to the voltage control attenuator 6, adjusts the amount of attenuation, and adjusts the pulse modulation. The power level of the signal is controlled to a predetermined constant value.

In this embodiment, when the control target is the voltage level control of the pulse modulation signal, the arithmetic circuit 21 having the square circuit connected to the feedback system may be deleted.

As described above, if the pulse modulation device in which the power level of the pulse modulation signal is controlled is applied to, for example, excitation of a laser oscillator, a laser output with an extremely fast pulse rise can be obtained. In addition, by applying the present device to an accelerator or plasma heating, a stable voltage or electric power can be supplied.

Note that the technology of the present invention is not limited to the technology in the above-described embodiment, and may be implemented by means of another embodiment that performs the same function. Addition is possible.

f. Effects of the Invention As is clear from the above description, according to the present invention, in a pulse modulation device that modulates a continuous high or ultra-high frequency signal with a pulse signal and outputs this through a voltage control attenuation means, A feedback circuit that feeds back part of the modulated signal, a sample-and-hold circuit that outputs the pulse signal as an analog signal, compares the analog signal with a predetermined level reference signal, and compares the difference signal with the voltage control attenuation signal. And a differential amplifying circuit for outputting the pulse modulated signal to the means.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a level control type pulse modulation device of the present invention. 3 pulse modulation circuit, 4 gate control signal (pulse signal) input terminal, 6 voltage-controlled attenuator, 16 feedback input terminal, 19 sample hold circuit, 22
…… Differential amplifier circuit, 23 …… Level control signal (DC voltage signal) input terminal.

Claims (1)

(57) [Claims] 1. A pulse modulation device for modulating a continuous high-frequency or ultra-high-frequency signal with a pulse signal and controlling the output level of the modulated signal by a voltage-controlled attenuating means. A directional coupler, a detection circuit that demodulates the pulse modulated signal branched by the directional coupler, a sample and hold control circuit that generates a sample and hold gate signal at a timing that matches the pulse signal, A sample-and-hold circuit that receives a sample-and-hold gate signal from a sample-and-hold control circuit, extracts a pulse signal demodulated by the detection circuit as a DC-converted analog signal value at the timing of the pulse signal, and samples and holds the sampled-and-held signal; ,
The analog signal held in the sample and hold circuit is
And a differential amplifier circuit for comparing the difference voltage with the level reference signal and outputting the difference voltage to the voltage control attenuating means, wherein the voltage level of the output pulse modulation signal is controlled to be constant. Type pulse modulator.