CN112468149A

CN112468149A - Device for inhibiting fluctuation of switching output signals of channels of multi-channel selector

Info

Publication number: CN112468149A
Application number: CN202011247013.0A
Authority: CN
Inventors: 付培华; 岑启锋; 丁承华; 赵万良; 黄韵弘; 石然
Original assignee: Shanghai Aerospace Control Technology Institute
Current assignee: Shanghai Aerospace Control Technology Institute
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-03-09

Abstract

The invention discloses a device for inhibiting fluctuation of switching output signals of a channel of a multiplexer, which comprises: the input channels are connected with a first operational amplifier respectively; a multiplexer having an input terminal connected to each of the first operational amplifiers; the input end of the analog-to-digital converter is connected to the output end of the multiplexer through a second operational amplifier; and the output end of each first operational amplifier is also connected with a grounded capacitor.

Description

Device for inhibiting fluctuation of switching output signals of channels of multi-channel selector

Technical Field

The invention relates to a spacecraft multipath signal high-precision data acquisition and conversion application occasion, in particular to a device for inhibiting fluctuation of a multipath selector channel switching output signal.

Background

The multiplexer is an integrated chip with multiple inputs and one output. The method is mainly used for the application of multi-channel signal transmission, such as multi-channel digital signals or multi-channel analog signals. In the signal transmission process, the multiplexer can sequentially select and conduct multiple signals at the input end according to requirements, and then the signals are output in a time-sharing mode and used for acquisition or data conversion of a post-stage circuit. The general multiplexer has different specifications such as 4-to-1, 8-to-1 or 16-to-1.

The signals that need to be acquired and converted on the spacecraft are very numerous, both analogue and digital. However, due to the limitation of the size of the spacecraft, the space of the signal acquisition and conversion circuit is limited, and the analog-digital conversion acquisition of each path of signal cannot be carried out independently. The use of the multiplexer can effectively solve the problem of the number of data acquisition conversion circuits, and reduce the hardware cost and the size. However, when the multiplexer is used, due to the fact that a parasitic capacitor or a filter capacitor is not properly used on a circuit transmission path, when signals are switched among different input channels, signals at an output end fluctuate. The fluctuation of the output end signal caused by channel switching can influence the stability of data acquisition or conversion of a post-stage circuit, and finally influences the reliable and stable operation of the spacecraft. Therefore, in the situation that the requirement for high-precision signal acquisition and conversion of the spacecraft is high, the fluctuation needs to be processed.

Disclosure of Invention

The invention aims to provide a device for inhibiting the fluctuation of an output signal of channel switching of a multiplexer, which can effectively solve the problem of output signal fluctuation caused by channel switching and improve the precision of signal acquisition and conversion.

In order to achieve the purpose, the invention is realized by the following technical scheme:

an apparatus for suppressing fluctuation of an output signal switched by a channel of a multiplexer, comprising:

the input channels are connected with a first operational amplifier respectively;

a multiplexer having an input terminal connected to each of the first operational amplifiers;

the input end of the analog-to-digital converter is connected to the output end of the multiplexer through a second operational amplifier;

and the output end of each first operational amplifier is also connected with a grounded capacitor.

The input channel provides an input signal, the signal is followed by the first operational amplifier, and the subsequent input signal of the operational amplifier is sent to the multiplexer through a grounding capacitor.

When the input channel needs to be switched, the grounding capacitor can provide instantaneous charge-discharge energy

The capacity of the grounding capacitor is 0.47 uF-10 uF.

Compared with the prior art, the invention has the following advantages:

the input and the output of the multiplexer are followed by the operational amplifier, so that the influence of the front and rear conditioning circuits on the signal voltage division on the real precision of the signal can be avoided. Meanwhile, each input end of the multiplexer is additionally provided with a capacitor, so that the problem of fluctuation of output signals of the multiplexer can be effectively solved. The circuit is simple to realize, has obvious effect of inhibiting signal fluctuation, and is suitable for most spacecraft application occasions.

Drawings

FIG. 1 is a circuit diagram of an apparatus for suppressing fluctuation of an output signal of a multiplexer channel switch according to the present invention;

FIG. 2a is a diagram illustrating the effect of the present invention;

FIG. 2b is a diagram showing the effect of the present invention.

Detailed Description

The present invention will now be further described by way of the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings.

As shown in fig. 1, an apparatus for suppressing fluctuation of an output signal switched by a multiplexer channel, includes: the input channels are connected with a first operational amplifier respectively; a multiplexer having an input terminal connected to each of the first operational amplifiers OP; the input end of the analog-to-digital converter AD is connected to the output end of the multiplexer through a second operational amplifier; and the output end of each first operational amplifier is also connected with a grounded capacitor. The input channel provides an input signal, the signal is followed by the first operational amplifier, and the subsequent input signal of the operational amplifier is sent to the multiplexer through a grounding capacitor. When an input channel needs to be switched, the grounding capacitor can provide instantaneous charge-discharge energy, and the capacity of the grounding capacitor is 0.47 uF-10 uF.

Furthermore, when the multi-path signals are input into the multiplexer, the operational amplifier is used for following, so that the impedance of the signals input into the multiplexer is reduced, the influence of the voltage division of a front-stage conditioning circuit on the signal precision can be reduced, and the influence of an overlarge slow charging circuit formed by an input resistor and a capacitor on the signal acquisition bandwidth is avoided. When channels are switched, the capacitors are charged and discharged inevitably after the channels are switched due to potential difference among different channels; meanwhile, due to the fact that the channel switching speed is high, the input end of the multi-path selector cannot provide enough energy instantaneously, and therefore signals of the output end fluctuate when the capacitor is charged and discharged instantaneously. In order to solve the problem, a capacitor with relatively large capacity is added at each channel input end of the multiplexer. When a certain channel is switched, other channels which are not switched input the capacitor to charge and store enough energy; when the channels are switched, even if potential difference exists between the front channel and the rear channel, when the capacitor is charged and discharged, the large capacitor at the input end can provide enough energy, the fluctuation of an output signal can be inhibited, and therefore the signal precision of a rear-stage acquisition or conversion circuit is improved. In addition, the output signals of the multiplexer need to be followed by the operational amplifier, and the following signals are sent to the analog-to-digital conversion chip AD for conversion, so that the impedance of the signals input to the AD can be reduced, and the accuracy of signal acquisition is improved.

Specifically, taking 4 input channels and a multiplexer as an example, the input channels have four channels, which are X1, X2, X3 and X4, respectively. One path of the output channel is Y. The input signals X1, X2, X3 and X4 respectively pass through a first operational amplifier OP for signal following. After the output of the first operational amplifier OP, a capacitor is respectively added to the ground, and the capacitance value range is recommended to be between 0.47uF and 10 uF. When the channel is switched, the large capacitor at the input end can provide instantaneous charge and discharge energy, and the stability of an output signal is ensured. The output signal is followed at the multiplexer output Y using a second operational amplifier OP. And the signals following the signals are sent to an analog-to-digital conversion chip AD for signal acquisition and conversion. Before and after the implementation, the comparison of the fluctuation suppression effect of the output signals of the multiplexers is shown in fig. 2a and fig. 2 b.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.

Claims

1. An apparatus for suppressing fluctuation of an output signal switched by a multiplexer channel, comprising:

2. The apparatus of claim 1 wherein the input channel provides an input signal which is followed by a first operational amplifier, and the operational amplifier follows the subsequent input signal through a grounded capacitor and then into the multiplexer.

3. The apparatus of claim 1 wherein the ground capacitor provides instantaneous charge-discharge energy when input channels need to be switched

4. The apparatus for suppressing switching of an output signal of a multiplexer channel as set forth in claim 1, wherein said ground capacitor has a capacity of 0.47uF to 10 uF.