RU2711470C1 - Phase-sensitive amplitude demodulator - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: invention relates to automatics and analogue conversion equipment and can be used for demodulation of analogue signals. Technical result is achieved by creating a phase-sensitive amplitude demodulator, which includes a buffer amplifier, a separating capacitor, a control shaper and a storage capacitor, as well as connections between available elements of the device.EFFECT: demodulation of sinusoidal signals.1 cl, 2 dwg

Description

The invention relates to the field of automation and analog converting technology and can be used for demodulation of analog signals.

Known demodulator [1] containing an operational amplifier, two keys, resistors.

The disadvantages of this device is the lack of a driver of key management signals and the presence of spurious pulsations in the output signal.

Closest to the proposed is a phase-sensitive amplitude demodulator containing the first and second input buses, a sign inverter, a comparator, two keys, an operational amplifier and resistors [2].

The disadvantage of this device is the demodulation of only signals "with the exception of the carrier frequency".

The problem to which this invention is directed is the demodulation of sinusoidal signals.

The problem is solved due to the fact that in the phase-sensitive amplitude demodulator containing the first and second input buses, the inputs of which are supplied respectively with modulated and control signals, a closing key, an operational amplifier, capacitor, resistors, according to the invention, an additional buffer amplifier is introduced, the input of which connected to the first input bus, and its output is connected through the input isolation capacitor to the input of the shorting key connected through the first resistor to the ground bus, the second input bus is connected to the input control driver, the output of which is connected to the control input of the closing key, the output of which is connected through a second resistor to the non-inverting input of the operational amplifier and to the input storage capacitor, which is connected to the ground bus, the inverting output of the operational amplifier is connected to the output of the operational amplifier and output bus.

The essential features of the claimed device, in comparison with the known (prototype), include the introduction of a buffer amplifier, an isolation capacitor, a control shaper and a storage capacitor, as well as a change in the connections between the existing elements of the device.

Such a circuit provides demodulation of sinusoidal signals due to the fact that the amplitude value of the signal is stored on the storage capacitor due to the short control pulse from the control driver.

In FIG. 1 shows a diagram of a device, FIG. 2 - diagrams of his work.

The proposed device contains a first 1 and second input bus 2, a buffer amplifier 3, a driver 4, an isolation capacitor 5, a first 6 and a second resistor 8, a closing switch 7, a storage capacitor 9, an operational amplifier 10 and an output bus 11.

The input of the buffer amplifier 3 is connected to the first input bus 1, and the output of the buffer amplifier 3 is connected through an isolation capacitor 5 to the input of the closing switch 7 connected through the first resistor 6 to the ground bus, the second input bus 2 is connected to the control driver 4, the output of which is connected to the control input of the closing switch 7, the output of which is connected through the second resistor 8 to the non-inverting input of the operational amplifier 10 and to the storage capacitor 9, which is connected to the ground bus, inverting the output operation The amplifier 10 is connected to the output of the operational amplifier and the output bus 11.

The proposed phase-sensitive amplitude demodulator operates as follows.

The first input 1 receives the amplitude-modulated signal (Fig. 2, a), and the second input 2 receives the reference frequency equal to the carrier frequency of the amplitude-modulated signal (Fig. 2, b). At the output of the control shaper 4, rectangular pulses are formed with a duty cycle 36, a frequency equal to the carrier frequency of the amplitude-modulated signal and phase shifted by 85 electrical degrees (Fig. 2, c), which open the closing switch 7, to the input of which through the input buffer 3 and an isolation capacitor 5 receives an amplitude modulated signal. In this case, fragments of the modulating signal will take place at the output terminal of the closing key 7, which, after being stored on the storage capacitor 9, will be converted into a modulating signal (Fig. 2d). If the carrier frequency of the amplitude-modulated signal coincides in phase with the reference frequency at input 2, then the output signal will have one phase shift, if they are out of phase, then the phase shift of the output signal will be reversed (Fig. 2e), i.e. . phase sensitive demodulation occurs. The input buffer 3 provides a high input impedance, and the operational amplifier 10 provides a low output impedance of the device. The separation capacitor 5 cuts off the parasitic constant component of the amplitude-modulated signal.

Using this device allowed us to create a high-quality amplitude phase-sensitive demodulator for operation as part of gyrostabilizers.

Sources of information:

1. J. Mache. Operational amplifiers and their application. L., Energy, 1974, p. 88, FIG. 5-60

2. RF patent No. 2312455, IPC H03K 7/02, H03K 9/02, H03D 3/18, priority dated March 28, 2006 (prototype).

Claims (1)

A phase-sensitive amplitude demodulator comprising a first and second input bus, a shorting key, an operational amplifier, first and second resistors, characterized in that it contains a buffer amplifier, the input of which is connected to the first input bus, and its output is connected through the input isolation capacitor to the input of the closing key connected through the first resistor to the ground bus, the second input bus is connected to the input control driver, the output of which is connected to the control input of the closing key, the output which is connected through a second resistor to the non-inverting input of the operational amplifier and to the inserted storage capacitor, which is connected to the ground bus, the inverting output of the operational amplifier is connected to the output of the operational amplifier and the output bus.

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