CN106161876A - A kind of circuit suppressing Earth noise to disturb - Google Patents

Abstract

The invention provides a kind of circuit suppressing Earth noise to disturb, including signal isolation and amplifier module, signal amplification module, load blocks, also include ground wire isolation module；First earth terminal of described signal isolation and amplifier module, the second earth terminal of described signal amplification module, the 3rd earth terminal of described load blocks are connected as signal ground；Described signal ground and publicly between be provided with the first diode group and the second diode group of reverse parallel connection, for described signal ground with isolate publicly.The present invention realizes video signal and the loop common mode disturbances formed publicly is greatly reduced, and improves video display effect, promotes and drives auxiliary experience.

Description

A Circuit for Suppressing Ground Noise Interference

technical field

The invention relates to the technical field of video processing, in particular to a circuit for suppressing ground noise interference.

Background technique

The Advanced Driver Assistant System (ADAS) collects environmental data inside and outside the car through sensors installed on the car, and performs technical processing such as identification, detection and tracking of static and dynamic objects, so that the driver can Active safety technology that detects possible dangers in the fastest time to attract attention and improve safety. Taking the panoramic parking assistance system of the advanced driving assistance system ADAS as an example, the images around the vehicle are collected by multiple cameras and displayed on the screen in the form of a virtual overhead view. screen to improve the driving assistance effect, enhance the assistance experience, and improve the parking safety factor.

At present, the various video circuits of ADAS (such as panoramic parking, semi-automatic parking, reversing assistance, etc.) are not affected by the inherent factors of the camera, and the circuit design for suppressing noise interference is not complete, especially for signal processing. The anti-interference design of the terminal circuit is poor, so that the display effect of the video signal on the LCD terminal is not good, and the video display shakes obviously and is easily interfered by the surrounding signals, which affects the driving assistance experience.

Contents of the invention

The technical problem to be solved by the present invention is to provide a circuit for suppressing ground noise interference, which isolates the video signal ground from the common ground through a diode, realizes ground floating, and reduces the loop common mode interference formed by the video signal and the common ground.

In order to solve the above technical problems, the present invention provides a circuit for suppressing ground noise interference, including:

The signal isolation output module has a signal input terminal, a first ground terminal and a signal output terminal, the signal input terminal inputs a video signal, and the signal output terminal outputs an isolated video signal;

The signal amplifying module has an amplifying input terminal, an amplifying output terminal and a second ground terminal, the amplifying input terminal is connected to the signal output terminal of the signal isolation output module, and the signal amplifying output terminal outputs an amplified video signal;

The load module has a load input terminal and a third ground terminal, the load input terminal is connected to the amplification output terminal of the signal amplification module; the third ground terminal is connected to the first ground terminal and the second ground terminal as a signal ground;

The ground isolation module includes two groups of diodes connected in parallel between the signal ground and the common ground, and is used for isolating the signal ground and the common ground.

Specifically, the video signal input by the signal input end is a video differential signal output after analog-to-digital conversion and digital-to-analog conversion of the initial video signal obtained from the video acquisition device.

Specifically, the signal isolation output module is a video isolation circuit, and the video isolation circuit is provided with a differential amplifier;

Specifically, the signal amplification module is a video buffer circuit;

Specifically, the two groups of diodes of the ground isolation module are connected in opposite directions.

Specifically, the circuit for suppressing ground noise interference further includes a DC stabilized power supply circuit, the fourth ground terminal of the DC stabilized power supply circuit is connected to the signal ground.

Specifically, the video isolation IC model in the video isolation circuit is BH7673G;

Specifically, the video buffer IC signal in the video buffer circuit is D2267;

Specifically, the type of the diode in the ground wire isolation module is 1N4148.

The circuit for suppressing ground noise interference provided by the present invention connects the first ground terminal of the signal isolation output module, the second ground terminal of the signal amplification module and the third ground terminal of the load module to form a signal ground, and passes the signal ground and the common ground through The two groups of diodes of the ground isolation module are isolated to realize ground floating, which greatly reduces the common mode interference of the loop formed by the video signal and the public ground, improves the anti-interference ability of the video signal to ground noise, improves the video display effect, and improves driving assistance experience.

Description of drawings

Fig. 1 is the structural representation of the circuit that suppresses ground noise interference that the present invention provides;

Fig. 2 is a specific circuit connection diagram of the circuit for suppressing ground noise interference provided by the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The values of the following components are only preferred embodiments, and do not constitute limitations on the scope of protection of the present invention.

Referring to Fig. 1 and Fig. 2, it is a structural schematic diagram and a circuit connection diagram of a circuit for suppressing ground noise interference provided by the present invention. In this embodiment, the circuit for suppressing ground noise interference mainly includes:

The signal isolation output module 100 has a signal input terminal 101, a first ground terminal 102 and a signal output terminal 103, the signal input terminal inputs a video signal, and the signal output terminal 103 outputs an isolated video signal;

The signal amplifying module 200 has an amplifying input terminal 201, an amplifying output terminal 202 and a second ground terminal 203, the amplifying input terminal 201 is connected to the signal output terminal 103 of the signal isolation output module 100, and the amplifying output terminal 202 outputs the amplified video signal;

The load module 300 has a load input terminal 301 and a third ground terminal 302, the load input terminal 301 is connected to the amplification output terminal 202 of the signal amplification module 200; the third ground terminal 302 is connected to the first ground terminal 102, the second ground terminal 302 The two ground terminals 203 are connected to the signal ground AGND;

The ground isolation module 400 includes two groups of diodes connected in antiparallel between the signal ground AGND and the common ground GND for isolating the signal ground AGND from the common ground GND. The connection direction of the two groups of diodes of the ground isolation module 400 is opposite, and the type and number are the same. as a group. The specific model of the diode can be 1N4148.

In this embodiment, the video signal input by the signal input terminal 101 is the differential video signal CVBS_O+, CVBS_O− outputted after the initial video signal obtained from the video acquisition device undergoes analog-to-digital conversion or digital-to-analog conversion.

In this embodiment, the signal isolation output module 100 is a video isolation circuit U1 (BH7673G), and the video isolation circuit U1 (BH7673G) is provided with a differential amplifier;

The video signal input terminal U1_PIN4 (VIN) and the bias input terminal U1_PIN5 (VGND) of the video isolation circuit U1 (BH7673G) are respectively connected to one end of the first capacitor C1 (1uF) and the second capacitor C1 (1uF), and the first capacitor The other end of C1 and the second capacitor C1 are respectively connected to the positive terminal CVBS_O+ and the negative terminal CVBS_O- of the differential video signal; the first ground terminal 102 is the ground terminal U1_PIN2 (GND) of the video isolation circuit U1 (BH7673G);

In this embodiment, the signal amplification module 300 is a video buffer circuit U2 (D2267). A third capacitor C3 (10uF) is connected between the amplification input terminal U2_PIN1 (VIN1) of the video buffer circuit U2 (D2267) and the signal output terminal U1_PIN1 (VOUT) of the video isolation circuit U1 (BH7673G). A regulator resistor R3 (1MΩ) is connected between the amplified input terminal U2_PIN1 (VIN1) of U2 (D2267) and the signal ground (AGND), which provides a discharge path for the transient current of the input signal, stabilizes the signal input voltage, and improves the video frequency. The working stability of the cache circuit U2 (D2267); the ground terminal U2_PIN2 (GND) of the video cache circuit U2 (D2267) is the second ground terminal.

In this embodiment, the voltage failure indication terminal U2_PIN3 (VSAG1) and the video signal output terminal U2_PIN4 (VOUT1) of the video buffer circuit U2 (D2267) are respectively connected to the positive terminal of the fourth capacitor C4 (22uF/16V) and the fifth The positive terminal of the capacitor C5 (100uF/16V), the negative terminal of the fourth capacitor C4 and the negative terminal of the fifth capacitor C5 are both connected to the load input terminal CVBS_OUT+ of the load module, and the load output terminal CVBS_OUT- of the load module That is, the third ground terminal, the load input terminal CVBS_OUT+ of the load module and the load output terminal CVBS_OUT- of the load module are connected to the LCD display.

In this embodiment, the circuit for suppressing ground noise interference further includes a DC stabilized power supply circuit 500, the fourth ground terminal of the DC stabilized power supply circuit 500 is connected to the signal ground AGND.

In the circuit for suppressing ground noise interference provided by the present invention, the video differential signal obtained from a camera or other video acquisition module after digital-to-analog conversion/analog-to-digital conversion is connected to the signal amplification from the signal input terminal 101 through the signal isolation output module 100 The amplification input terminal 201 of the module 200 is connected to the load input terminal 301 of the load module 300 from the amplification output terminal 202 after being amplified by the signal amplification module 200, as the positive terminal of the signal loop; the first ground terminal 102 of the signal isolation output module 100, The second ground terminal 203 of the signal amplifying module 200 is connected with the third ground terminal 302 of the load module 300 to form the signal ground AGND, which serves as the negative terminal of the signal loop.

The two groups of diodes of the ground isolation module 400 are connected in parallel between the signal ground AGND and the common ground GND to isolate the signal ground from the common ground GND. The first group of diodes D2 and D4 use forward connection to isolate the third ground terminal CVBS_OUT- of the load module 300 from the common ground GND, preventing various clutter on the common ground GND from disturbing the third ground terminal of the load module On CVBS_OUT-, interfere with the video signal. If there is noise on the common ground GND, the video signal input terminal U2_PIN1 (VIN1) of the video buffer circuit U2 (D2267) of the signal amplifying module 300 is channeled to the video signal input terminal U2_PIN1 (VIN1) of the video buffer circuit U2 (D2267) of the signal amplification module 300 through the second group of diodes D1 and D3 connected in reverse, because the video signal A loop is formed between the input terminal U2_PIN1 (VIN1) and the signal ground AGND. At this time, the interference signal on the signal ground AGND is the same as the interference signal on the video signal input terminal U2_PIN1 (VIN1), that is, the signal passing through the video buffer circuit U2 (D2267) The amplitude of the positive and negative terminals of the video signal remains unchanged, and the noise interference from the common ground GND just floats the video signal up and down as a whole. In this way, the signal ground AGND and the common ground GND can withstand the interference fluctuation range of nearly twice the diode conduction voltage drop, so that the circuit has a strong enough anti-interference ability. The relationship between the number n of diodes connected in series in the same direction in each group, the conduction voltage drop Vf and the anti-interference amplitude Vr can be expressed as: n>[Vr/Vf] ([] indicates rounding).

In this embodiment, the first diode group D2, D4 and the second diode group D1, D3 of the ground line isolation module 400 isolate the signal ground AGND from the common ground GND, so that the two grounds can withstand nearly The dynamic range of 1.4V (take the diode conduction voltage drop Vf = 0.7V).

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (8)

1. suppress the circuit that Earth noise disturbs, including signal isolation and amplifier module, signal amplification module, load blocks, its It is characterised by: also include ground wire isolation module；

First earth terminal of described signal isolation and amplifier module, the second earth terminal of described signal amplification module, described load mould 3rd earth terminal of block is connected as signal ground；

Described signal ground and publicly between be provided with the first diode group and the second diode group of reverse parallel connection, for institute State signal ground and isolate publicly.

2. the circuit of suppression Earth noise interference as claimed in claim 1, it is characterised in that: described first diode group and second Number of diodes in diode group is identical, model is identical, and when described number of diodes is more than 1, described diode is gone here and there in the same direction Connection.

3. the circuit of suppression Earth noise interference as claimed in claim 1, it is characterised in that: described signal isolation and amplifier module is Video isolation circuit.

4. the circuit of suppression Earth noise interference as claimed in claim 1, it is characterised in that:

Described signal amplification module is video cache circuit.

5. the circuit of suppression Earth noise interference as claimed in claim 1, it is characterised in that: also include D.C. regulated power supply electricity Road, the 4th earth terminal of described DC-stabilized circuit connects signal ground.

6. the circuit of suppression Earth noise interference as claimed in claim 2, it is characterised in that:

The model of described diode is 1N4148.

7. the circuit of suppression Earth noise interference as claimed in claim 3, it is characterised in that:

The video isolation IC model of described video isolation circuit is BH7673G.

8. the circuit of suppression Earth noise interference as claimed in claim 4, it is characterised in that:

Video cache IC model in described video cache circuit is D2267.