CN2662594Y

CN2662594Y - Circuit preventing electromagnetic noise signal

Info

Publication number: CN2662594Y
Application number: CN 200320123736
Authority: CN
Inventors: 王胜弘
Original assignee: Mitac Technology Corp
Current assignee: Getac Technology Corp
Priority date: 2003-11-27
Filing date: 2003-11-27
Publication date: 2004-12-08
Anticipated expiration: 2013-11-27

Abstract

The utility model relates to a circuit that can prevent electromagnetic noise signals and is used for preventing ground bounce on integrated circuit(IC) from being transmitted to the printing circuit board(PCB). A through capacitor is connected between the ground end of the integrated circuit and the ground side of the printing circuit board. The utility model can filter DC noise signals on the integrated circuit and the AC noise signals of different frequencies by employing the property of equaling to capacitor when the AC passes through at the time when the capacitor is short cut when the DC passes through by changing the amount of the capacitance. Thus, the aim of preventing the ground bounce signals from being transmitted to the printing circuit board is achieved.

Description

Prevent the circuit of electromagnetic noise signal

Technical field

The utility model is the circuit that prevents the electromagnetic noise signal about a kind of, refers to that especially a kind of ground noise signal that can prevent integrated circuit conducts on the printed circuit board (PCB) and produces the circuit design of electromagnetic interference (EMI Noise).

Prior art

Generally be assembled in printed circuit board (PCB) (Printed Circuit Board, PCB) (the Integrated Circuit of the integrated circuit on, IC) have a power end and an earth terminal on usually, be equipped with grounding leg on the earth terminal, power end is just being connected or during deenergization, having pulse produces, make on the earth terminal of integrated circuit (IC) and therefore can produce ground noise signal (ground bounce), in order to prevent that the ground noise signal is transmitted on the printing board PCB, traditional method is: the grounding leg of integrated circuit (IC) is directly connected on the ground plane on the printing board PCB, and the ground noise signal will be because of decaying by the ground plane on the printing board PCB.

But, goes up at a high speed and high density structure dress by electronic component along with stepping, the ground noise signal effect that earth terminal produced of integrated circuit (IC) is more and more higher, the area of the ground plane on the printing board PCB and level also directly have influence on and whether can effectively eliminate the ground noise signal in addition, if the area and the not enough words of level of ground plane on the printing board PCB, just can't effectively make ground noise signal decay on the ground plane of printing board PCB, so in order effectively to eliminate the ground noise signal, usually need to increase the level and the thickness of printing board PCB, therefore increased the cost of printing board PCB.

Summary of the invention

Because the defective of above-mentioned prior art, a kind of circuit that prevents the electromagnetic noise signal is proposed, prevent that the ground noise signal on the integrated circuit (IC) from conducting on the printing board PCB, it is to run through electric capacity (through capacitor) by one to filter out ground noise signal on the electronic component, prevents that it is delivered on the printing board PCB.

Main purpose of the present utility model: provide a kind of circuit that prevents the electromagnetic noise signal simple and easy and with low cost, it is that serial connection one runs through electric capacity between the ground plane of the earth terminal of integrated circuit (IC) and printing board PCB, utilize this to run through electric capacity short circuit when direct current passes through, alternating current by the time be equivalent to the characteristic of electric capacity, filter out direct current and AC noise signal on the integrated circuit (IC), conduct to purpose on the printing board PCB to reach the ground noise signal that prevents on the integrated circuit (IC), in addition because the ground noise signal does not need the area or the level of the ground plane by increasing printing board PCB to eliminate, the therefore expense that can save printing board PCB.

Description of drawings

Below, with reference to accompanying drawing, for those skilled in the art that, to the detailed description of the present utility model, above-mentioned and other purposes of the present utility model, feature and advantage will be apparent.

Fig. 1 is a circuit box schematic diagram of the present utility model.

Embodiment

See also shown in Figure 1ly, (Integrated Circuit IC) has a power end 101 and an earth terminal 103 on 1 to integrated circuit.One power pin 102 is arranged on the power end 101, a grounding leg 104 is arranged on the earth terminal 103.

(Printed Circuit Board PCB) has a ground plane 201 on 2 to printed circuit board (PCB), and a pin 202 is arranged on the ground plane 201.

What be serially connected with an adjustable condenser size between the grounding leg 104 on the integrated circuit (IC) 1 and the pin 202 of printing board PCB 2 runs through electric capacity (through capacitor) 3, and this runs through electric capacity 3 ground connection.

When the power pin 102 of integrated circuit (IC) 1 is switched on or switched off power supply suddenly, can produce pulse in the integrated circuit (IC) 1, can therefore can produce ground noise signal (groundbounce) on the ground plane 103 of integrated circuit (IC) 1, the ground noise signal conducts to by grounding leg 104 and runs through in the electric capacity 3, owing to run through electric capacity 3 short circuit when direct current passes through, alternating current by the time be equivalent to the characteristic of electric capacity, so can filter out the dc noise signal on the integrated circuit (IC) and and run through the close AC noise signal of electric capacity 3 frequencies.Again owing to the capacitance size that runs through electric capacity 3 can be regulated, so can be according to the difference of different AC noise frequencies that signal has, according to formula: f=1/2 Lamb-soup (LC), electric capacity (C) size that adjustment runs through electric capacity 3 makes frequency (f) size that runs through electric capacity 3 big or small close with the frequency of ground noise signal, thereby can be according to the size of the different AC noise signal frequencies that produced, adjust the capacitance size that runs through electric capacity 3, filter out the AC noise signal that is produced.

The foregoing description is to be serially connected between integrated circuit (IC) 1 and the printing board PCB 2 on the circuit running through electric capacity 3; Also can directly be serially connected on the grounding leg of integrated circuit (IC); Or the electric capacity that runs through that on the pin of printing board PCB, is connected in series a ground connection, according to the characteristic that runs through electric capacity as mentioned above, also can filter out in the integrated circuit (IC) or the ground noise signal on the printing board PCB; Add one at the earth terminal of radio-frequency line and run through electric capacity, also can filter out the ground noise signal of radio-frequency line.

In sum, the utility model runs through electric capacity by one, can reach to prevent the purpose that the electromagnetic noise signal produces and do not interfere with other electron component.

Above-mentioned the utility model only illustrates with most preferred embodiment, to be familiar with this technical field general personnel, when carrying out various variations, these variations all should be included in spirit of the present utility model and claims.

Claims

1. circuit that prevents the electromagnetic noise signal, include a printed circuit board (PCB) (PCB) of tool ground plane and be arranged on a integrated circuit (IC) on this printed circuit board (PCB), described integrated circuit tool one earth terminal and a grounding leg that links to each other with this earth terminal, with printed circuit board (PCB) on the corresponding pin of ground plane join;

Be serially connected with one and run through electric capacity between integrated circuit grounding leg and printed circuit board (PCB) pin, this runs through the other end ground connection of electric capacity.

2. the circuit that prevents the electromagnetic noise signal according to claim 1 is characterized in that, described integrated circuit is a kind of radio-frequency line.

3. the circuit that prevents the electromagnetic noise signal according to claim 1,

It is characterized in that the described capacitance that runs through electric capacity can be adjusted.

4. circuit that prevents the electromagnetic noise signal, include a printed circuit board (PCB) (PCB) of tool ground plane and be arranged on a integrated circuit (IC) on this printed circuit board (PCB), described integrated circuit tool one earth terminal and a grounding leg that links to each other with this earth terminal, with printed circuit board (PCB) on the corresponding pin of ground plane join;

This grounding leg of this integrated circuit is serially connected with one and runs through electric capacity, and this runs through the other end ground connection of electric capacity.

5. the circuit that prevents the electromagnetic noise signal according to claim 4 is characterized in that, described integrated circuit is a kind of radio-frequency line.

6. the circuit that prevents the electromagnetic noise signal according to claim 4,

7. circuit that prevents the electromagnetic noise signal, include a printed circuit board (PCB) (PCB) of tool ground plane and be arranged on a integrated circuit (IC) on this printed circuit board (PCB), described integrated circuit tool one earth terminal and a grounding leg that links to each other with this earth terminal, with printed circuit board (PCB) on the corresponding pin of ground plane join;

This pin of this printed circuit board (PCB) is serially connected with one and runs through electric capacity, and this runs through the other end ground connection of electric capacity.

8. the circuit that prevents the electromagnetic noise signal according to claim 7 is characterized in that, described integrated circuit is a kind of radio-frequency line.

9. the circuit that prevents the electromagnetic noise signal according to claim 7,

It is characterized in that the described capacitance that runs through electric capacity is to adjust.