JPH0425260A - Phase modulation circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for the adjustment and to reduce the cost by utilizing noninverting and inverting amplification of an operational amplifier and phase rotation action of a capacitor for generating four phase states different by 90 deg. each. CONSTITUTION:A NOT computing element 10 connects to a control terminal of a 2nd changeover device 2 and when, e.g. a 1st changeover device 1 is closed, the 2nd changeover device 2 is opened, an inputted carrier is amplified inversely by an operational amplifier 6 and an output signal inverse to the input carrier, that is, whose phase differs from 180 deg. is outputted from a modulation output terminal 24. Then a binary digital data signal is inputted from a data input terminal 23 to a 3rd changeover device 3 to be opened or closed thereby selecting the state as to whether or not phase rotation of 90 deg. is to be given. Finally four phase states of 0 deg., 90 deg., 180 deg., 270 deg. are taken depending on the binary digital data signal given to the 1st and 2nd data input terminals 22, 23 in this way and the resulting signal is outputted from the modulation output terminal 24. Thus, no adjustment and low-cost are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switching type phase modulation circuit used in digital data transmission and the like.

[Conventional technology]

Traditionally, a so-called ring modulation circuit that uses diodes, transformers, etc. is often used as a typical switching type phase modulation circuit, but the ring modulation circuit requires four well-balanced diodes. Also, since it uses a transformer, it was essential to adjust the balance.

[Problem to be solved by the invention]

The above-mentioned conventional phase modulation circuit has the drawback that as the number of phases increases from two phases to four phases, the balance between each phase becomes finely adjusted, and therefore a large amount of time is required for adjustment. Further, there was a drawback that the cost was increased due to the use of transformers and the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a phase modulation circuit that can be made without adjustment and can be configured with inexpensive components.

[Means to solve the problem]

The phase modulation circuit of the present invention has a first and second phase modulation circuit that switches an input carrier signal by a signal from each switching control terminal.
a control input circuit that supplies a first digital data signal and its inverted signal to respective switching control terminals of the first and second switching devices;
an operational amplifier that inputs and amplifies each output of the switching device into in-phase and anti-phase terminals, respectively; a feedback resistor that connects the output of this operational amplifier to an anti-phase input terminal of the operational amplifier; The feedback circuit includes a capacitor and a third switch connected in parallel, and a second digital data signal is input to a switching control terminal of the third switch.

〔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 embodiment shown in FIG. 1, 21 is a carrier wave input terminal, 1.2.3 is a switch with an external control terminal, 4.5 is an input resistor, 6 is an operational amplifier, 7 is a feedback resistor, 8 is a reference resistor, and 9 is a capacitor,
Reference numeral 10 indicates an inverter serving as an input control circuit, reference numerals 22 and 23 indicate first and second data input terminals, and reference numeral 24 indicates a modulation output terminal.

The carrier wave input from the carrier wave input terminal 21 is applied to the in-phase and anti-phase input terminals of the operational amplifier 6 via the first and second switching devices 1 and 2 and the input resistor 4.5. This operational amplifier 6 includes a feedback resistor 7 that determines the gain of the operational amplifier.
and a resistor 8 that determines the operating reference voltage of the operational amplifier. - On the other hand, the binary digital data signal input to the first data input terminal 22 is applied to the external control terminal of the first switch 1 and is passed through the negation operator 10 to the second
is applied to the external control terminal of the switch 2.

These first and second switching devices 1 and 2 are controlled to be conductive or non-conductive depending on the state of a binary digital signal applied to their external control terminals, and the control terminal of the second switching device 2 is
Since the negation operator 10 is connected, for example, when the first switch 1 is in a conductive state, the second switch 2 is in a non-conductive state. In such a state of the switchers 1 and 2, the input carrier wave is in-phase amplified by the operational amplifier 6, and an output signal having the same phase as the input carrier wave is output to the modulation output terminal 24. Conversely, when the first switch l is in a non-conducting state and the second switch 2 is in a conducting state, the input carrier wave is amplified in reverse phase by the operational amplifier 6, so that the modulated output is An output signal having a phase opposite to that of the input carrier wave, that is, having a phase difference of 180° is outputted to the terminal 24 . Therefore, the phase of the input carrier wave corresponds to the state of the binary digital data signal input to the first data input terminal 22, from 0° (in phase) to 1°.
There are two states of 80° (opposite phase). Further, a third switch 3 and a capacitor 9 are connected in parallel to the feedback resistor 7 of the operational amplifier 6, so that when the third switch 3 is in a conductive state, the phase of the carrier wave passing through the operational amplifier 6 is changed to 9.
Select the constant of capacitor 9 so that it rotates by 0°. Under such circuit conditions, a binary digital data signal is input to the third switch 3 from the second data input terminal to switch whether or not to apply a phase rotation of 90' as a conductive or non-conductive state. . In this way, the first. Depending on the states of the binary digital data signals at the second data input terminals 22 and 23 (ie, 00, 01.10°11), the result is 0° and 90'.

It takes four phase states of 180° and 270° and is output to the modulation output terminal 24. With such a circuit configuration, the phase of the input carrier wave signal can be extracted by being subjected to four-phase phase modulation using two binary digital data signals.

〔Effect of the invention〕

As explained above, the present invention uses the in-phase and anti-phase amplification effects of the operational amplifier and the phase rotation effect of the capacitor to create four phase states that differ by 90 degrees, so no adjustment is required. Furthermore, it is possible to use widely used and low-cost components for the circuit. Therefore, compared to the conventional example, it is possible to construct a switching type four-phase phase modulation circuit that requires no adjustment and is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention. 1... first switch, 2... second switch, 3...
・Third switch, 4, 5, 7.8...Resistor, 6...
Operational amplifier, 9... Capacitor, 10... Notation unit, 21... Carrier wave input terminal, 22... First data input terminal, 23... Second data input terminal, 24...
...Modulation output terminal.

Claims (1)

[Claims] 1. First and second switching devices that respectively switch input carrier signals according to signals from respective switching control terminals; a control input circuit that supplies a digital data signal and its inverted signal, an operational amplifier that inputs and amplifies the outputs of the first and second switching devices to in-phase and anti-phase terminals, respectively; a feedback resistor that connects the output of the operational amplifier to an opposite-phase input terminal of the operational amplifier; a feedback circuit that includes a capacitor and a third switch connected in parallel with the feedback resistor; A phase modulation circuit characterized in that a second digital data signal is input to a switching control terminal of the device. 2. The capacitance value of the capacitor is selected so that the phase of the carrier signal passing through the operational amplifier is shifted by 90 degrees when the third switch is turned on by the second digital data signal. The phase modulation circuit according to claim 1, characterized in that: