JPS63272114A - Alc circuit - Google Patents

Abstract

PURPOSE:To make a detector, a variable attenutor, etc., unnecessary by connecting a bias voltage controlled circuit at a frequency multiplier, comparing respectively the voltage of a resistance for a self-bias and a variable resistance for setting a level for the bias voltage control circuit and keeping constantly the voltage for the self-bias. CONSTITUTION:When a variable resistance 8 for setting a level is set to a prescribed resistance value and one input terminal voltage of an operational amplifier 6 is set to a prescribed voltage, the operational amplifier 6 compares the voltage of both edges of a resistance 9 for a self-bias, namely, other input terminal voltage of the operational amplifier 6. The gate voltage of an FET7 outputted from the output terminal is changed, the source drain current of the FET7 is controlled, and the control is executed so that other input terminal voltage can be coincident to one side input terminal voltage, namely, the prescribed level-set voltage. Consequently, the voltage at the resistance 9 for the self-bias, namely, a signal level at a diode 5 for multiplying can be stably kept to a set value. Thus, a variable attenuator, a detector and a variable attenuator control circuit are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave band signal generation circuit, and in particular to an ALC (automatic Lecture) circuit that maintains a constant output signal level.
vel Control ) circuit.

[Conventional technology]

Conventional microwave band ALC circuits use a microwave band detector to detect the output signal level and a microwave band variable attenuator to control the signal level based on the output voltage of the detector in order to keep the output signal level constant. was used.

For example, as shown in FIG. 3, a microwave band variable attenuator 11 and a microwave band detector 10 are connected to the path from the microwave band oscillator 1 to the output terminal 4 via the frequency multiplier 2, and the detection A microwave band variable attenuator control circuit 12 is connected to the microwave band variable attenuator control circuit 12 which controls the microwave band variable attenuator 11 based on the output of the microwave band variable attenuator 11 .

Then, based on the detection output of the wave detector 10, the variable attenuator 1
1 is controlled by the control circuit 12 to keep the output signal level at the output terminal 4 constant.

[Problem that the invention seeks to solve]

The conventional ALC circuit described above includes a detector 10 that detects the output signal level and a variable attenuator 1 that controls the signal level.
1 and its control circuit 12, the configuration was complicated and expensive.

An object of the present invention is to provide an ALC circuit that has a simple configuration and can be manufactured at low cost.

[Means for solving problems]

The ALC circuit of the present invention connects a frequency multiplier to a bias voltage control circuit that can apply a bias voltage using a self-bias resistor, and uses this bias voltage control circuit to control the voltage of the self-bias resistor and the level setting variable resistor. The configuration is such that the voltage of the self-biasing resistor is kept constant by comparing them, thereby achieving a constant output signal level.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

1 is a microwave band oscillator, 2 is a frequency multiplier, and 4
A signal is output from the microwave band signal output terminal. The frequency multiplier 2 includes a bias voltage control circuit 3.
are connected.

FIG. 2 is a circuit diagram of the multiplication diode portion of the frequency multiplier 2 and the bias voltage control circuit 3. In the figure, 5 is a multiplier diode, 6 is an operational amplifier, and 7 is a field effect transistor (FET). A variable resistor for level setting is connected to one input terminal of the operational amplifier 6, and an output terminal of the operational amplifier 6 is connected to the gate of the FET 7. The other input terminal of the operational amplifier 6 is connected to the multiplier diode 5, and a self-biasing resistor 9 is connected between the parenthesized input terminal and the source of the FET 7.

According to this configuration, when the level setting variable resistor is set to a predetermined resistance value and the voltage at one input terminal of the operational amplifier 6 is set to a predetermined voltage, the operational amplifier 6 receives the voltage across the self-biasing resistor 9, that is, the operational amplifier 6 The FE output from the output terminal is compared with the other input terminal voltage.
The source/drain current of FET 7 is controlled by changing the gate voltage of T7, and the voltage of the other input terminal is controlled to match the voltage of one input terminal, that is, the predetermined voltage whose level is set. Thereby, the voltage at the self-biasing resistor 9, ie, the signal level at the multiplier diode 5, can be stably maintained at the set value.

According to this configuration, the output signal level can be maintained constant without using a conventional variable attenuator, a wave detector, and a variable attenuator control circuit, and the circuit configuration can be simplified.

〔Effect of the invention〕

As explained above, the present invention connects a bias voltage control circuit to a frequency multiplier, and connects the bias voltage control circuit to a frequency multiplier.
Since the voltage of the self-bias resistor is kept constant by comparing the voltage of the self-bias resistor and the voltage of the level setting variable resistor, it is possible to achieve a constant output signal level in the signal generation circuit just by providing this circuit. , a simple and inexpensive ALC that does not require a detector or variable attenuator, etc.
The circuit can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a bias voltage control circuit diagram in this embodiment, and FIG. 3 is a block diagram of a conventional ALC circuit. DESCRIPTION OF SYMBOLS 1... Microwave band oscillator, 2... Microwave band multiplier, 3... Bias voltage control circuit, 4... Output terminal, 5... Multiplier diode, 6... Operational amplifier, 7
... Field effect transistor, 8... Variable resistor for level setting, 9... Resistor for self-bias, 10... Microwave band detector, 11... Microwave band variable attenuator, 12...・Microwave band variable attenuator control circuit. Figure 1 Figure 3

Claims (2)

[Claims] (1) In a signal generation circuit including an oscillator and a frequency multiplier, a bias voltage control circuit capable of applying a bias voltage through a self-bias resistor is connected to the frequency multiplier, and this bias voltage control circuit is configured to control the self-bias An ALC circuit characterized in that the voltage of the self-biasing resistor is kept constant by comparing the voltages of the self-biasing resistor and the level setting variable resistor. (2) A self-bias resistor and a level setting variable resistor are connected to each input terminal of the operational amplifier, and the self-bias resistor is connected to the source and drain of a field-effect transistor, and the gate voltage of this field-effect transistor is set to the 2. The ALC circuit according to claim 1, wherein the ALC circuit is configured to be controlled by the output of an operational amplifier.