JPH01250768A - Phase difference detecting circuit - Google Patents

Abstract

PURPOSE:To obtain a detecting circuit of simple construction, by a method wherein levels of outputs of two signals combined to be of a reverse phase and the same phase in a four-terminal hybrid are subjected to subtraction and amplification in a differential amplifier. CONSTITUTION:Two different signals inputted to input terminals 1 and 2 are combined to be of a reverse phase and the same phase in a four-terminal hybrid 3 respectively, and a reverse-phase composite signal is outputted to a reverse- phase output end 3A, while the same-phase composite signal is outputted to the same-phase output end 3B. The signals are detected by level detectors 4 and 5 and outputted as DC voltages. These output voltages A and B have characteristics corresponding to a phase difference between the two input signals. Next, these voltages A and B are subjected to subtraction and amplification by a differential amplifier 6 and thereby an output voltage C is obtained. The output voltage C turns to be an output voltage having a prescribed relation to the two signals in accordance with the phase difference between them. The phase difference between the two signals can be detected therefrom, and a detection voltage is outputted from an output terminal 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phase difference detection circuit for detecting a phase difference between two input signals.

[Conventional technology]

Conventionally, as a circuit for detecting the phase difference between two input signals,
A double balanced mixer (double balanced modulator) is used. This double balanced modulator connects two balanced modulators symmetrically and inputs one signal to each balanced modulator, while
One other signal is input to each balanced modulator at a different phase, resulting in the output of the difference between the two signals, from which the phase difference is detected.

[Problem to be solved by the invention]

The conventional circuit described above uses a double-balanced modulator that directly compares the phases of two signals, but this double-balanced modulator has a relatively complicated circuit configuration.

An object of the present invention is to provide a phase difference detection circuit with a simple circuit configuration.

[Means to solve the problem]

The phase difference detection circuit of the present invention includes a four-terminal hybrid that combines two input signals in opposite phase and in phase, and two level detectors that respectively detect the combined signals of opposite phase and in-phase output from this hybrid. and a differential amplifier that subtracts and amplifies each output voltage of these level detectors.

[Effect]

In the configuration described above, it is a four-terminal hybrid with opposite phases.

By subtracting and amplifying the output levels of two signals combined in the same phase in a differential amplifier, an output of 11 voltages can be obtained according to the phase difference between the two signals, and a double-balanced modulator is used. The same detection is achieved.

〔Example〕

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

FIG. 1 is a circuit diagram of an embodiment of the present invention. In the figure, 1.2 are input terminals for two different signals, and each input terminal 1.2 is an input terminal for two different signals. 2 is connected to a four-terminal hybrid 3 which combines these input signals in anti-phase and in-phase. A level detector 4.5 for detecting each signal is connected to the negative phase output terminal 3A and the in-phase output terminal 3B of this four-terminal hybrid 3, and each level detector 4, 5 subtracts and amplifies the detected signal on each side. The output terminal 7 is connected to a differential amplifier 6 that outputs a detected voltage from an output terminal 7.

In this circuit, the two input signals at the input terminals 1 and 2 have opposite phases in the four-terminal hybrid 3.

The signals are combined in the same phase, and the negative phase combined signal is output to the negative phase output terminal 3A, and the in-phase combined signal is output to the common phase output terminal 3B. Each signal is then detected by a level detector 4.5 and output as a DC voltage. These output voltages A, B (first
The voltages at points A and B in the figure) have characteristics as shown in FIG. 2 due to the phase difference between the two input signals.

Then, by subtracting and amplifying these voltages A and B using the differential amplifier 6, the output voltage C (voltage at point C in FIG. 1) becomes as shown in FIG.

As a result, the output voltages have a predetermined relationship depending on the phase difference between the two signals, and the phase difference between the two signals can be detected. This is the same as the phase difference detection output using a double balanced modulator.

〔Effect of the invention〕

As explained above, the present invention subtracts and amplifies the output levels of two signals that are synthesized in phase and in phase using a four-terminal hybrid. It is possible to obtain an output voltage according to the phase difference between the two, and the circuit can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the detected voltages at points A and B in FIG. 1, and FIG. 3 is a diagram showing the output voltage at point 0 in FIG. 1. It is. 1.2...Signal input terminal, 3...Four terminal hybrid, 3A...Negative phase output terminal, 3B...In-phase output terminal, 4゜5...Level detector, 6...Difference dynamic amplifier, 7
...Output terminal. Figure 1 Figure 2 Ie J Eye No. 1 Figure 3

Claims (1)

[Claims] 1. A four-terminal hybrid that combines two input signals in antiphase and in-phase, two level detectors that respectively detect the anti-phase and in-phase composite signals output from this hybrid, and these level detectors. A phase difference detection circuit comprising: a differential amplifier that subtracts and amplifies each output voltage.