CN203467065U - Printed circuit board - Google Patents

Abstract

The utility model provides a printed circuit board. The printed circuit board is provided with a filter circuit and an IC device, wherein a conductive connecting line between the power supply pins of the filter circuit and the IC device is a spiral line. The magnetic lines of the spiral line are concentrated, equivalent to a certain inductance and equivalent to adding a stage of filtering after the filter circuit. The printed circuit board is simple in implement, zero in cost, and is capable of improving the filter circuit' capability of inhibiting power supply noises.

Description

A kind of printed circuit board (PCB)

Technical field

The utility model relates to printed-board technology field, relates in particular to a kind of printed circuit board (PCB).

Background technology

Current PC B(Printed Circuit Board, printed circuit board (PCB)) the IC(integrated circuit on, integrated circuit) device is used Switching Power Supply power supply more, yet switching power supply noise is large, for circuit extremely responsive to noise on some IC devices, such as PLL(Phase Locked Loop, phase-locked loop) circuit, guarantee power supply noise and disturb and effectively suppressed, conventionally need to increase LC filter circuit, as shown in Figure 1, power supply VCC is after the filtering of LC filter circuit, and output VCC_PLL powers to PLL.At present, on PCB, the conductive connecting between LC filter circuit and the PLL pin of IC device, normally by laying copper sheet, or the mode of walking thick copper lines as shown in Figure 2.

But existing this on PCB, conductive connecting between LC filter circuit and device power source pin, adopts the wire laying mode of laying copper sheet or thick copper lines, poor to the filter effect of power supply noise.

Utility model content

In view of this, the utility model provides a kind of printed circuit board (PCB), by printed circuit board (PCB), the wire laying mode between LC filter circuit and device power source pin being improved, improves the inhibition ability of printed circuit board (PCB) to power supply noise.

The utility model provides a kind of printed circuit board (PCB), is provided with filter circuit and integrated circuit (IC) device on described printed circuit board (PCB), and the conductive connecting between filter circuit and the power pin of IC device is helix.

Preferably, the conductive connecting between described filter circuit and the phase-locked loop pll power pin of IC device is helix.

Preferably, described helix adopts square spiral.

Preferably, described helix is positioned at the internal layer wiring layer of printed circuit board (PCB).

Preferably, described filter circuit is LC filter circuit.

The printed circuit board (PCB) that the utility model provides, by conductive connecting between filter circuit and the power pin of IC device is arranged to helix, power supply is passed through after filter circuit filtering, while exporting IC device to by helix, can there is lower power supply noise, improve the inhibition ability of printed circuit board (PCB) to power supply noise.

Accompanying drawing explanation

Fig. 1 is LC filter circuit schematic diagram;

Fig. 2 is the schematic diagram by walking to lay thick copper lines, filter circuit being connected with the power pin of IC device in existing PCB;

Fig. 3 is the PCB layout schematic diagram by laying helix, filter circuit being connected with the power pin of IC device in the PCB that provides of the utility model;

Fig. 4 is spiral inductance computing formula parameter schematic diagram;

Fig. 5 is that schematic diagram is answered in the width-frequency response of filter circuit in existing PCB;

Fig. 6 is that the width-frequency response of filter circuit in the PCB that provides of the utility model should.

Embodiment

The utility model provides a kind of pcb board, on pcb board, be provided with filter circuit and IC device, wherein, the conductive connecting between the power pin between filter circuit and IC device is helix, on PCB, power supply is after filtering after circuit filtering, by PCB, go up the helix of laying, export filtered power supply to IC device, here by laying helix, can be equivalent to form secondary filtering by connecting wire, thereby can improve the inhibition ability of PCB to power supply noise.

As shown in Figure 3, illustrated the wiring on pcb board, particularly, on layer printed circuit board on pcb board 10, be laid with the first welding disking area 11 that filter circuit is installed, and the second welding disking area 12 that IC device is installed, this first welding disking area 11 arranges near the second welding disking area 12, the first pad 111 in the first welding disking area 11, be set as helix 13 with the wire cloth that is connected between the second pad 112 in the second welding disking area 12, wherein, the first described pad 11 is corresponding to output in LC filter circuit, the second pad 112 is corresponding to the power pin on IC device, making to be installed to filter circuit on pcb board and the connection wire between the power pin of IC device is helix 13.It will be understood by those skilled in the art that the wiring on described pcb board is copper cash, described helix 13 is Copper Foil wire.Wherein, the specific implementation process of the wiring on PCB realizes identically or similar with existing, and the wiring copper cash that just connects filter circuit and IC device is helix.

The utility model, by the wire laying mode between filter circuit on pcb board and device power source pin is designed to helix, suppresses the defect of scarce capacity thereby overcome the wire laying mode between filter circuit and device power source pin in prior art to power supply noise.Wherein, the helix of laying, can play the effect that the power supply noise of circuit suppresses after filtering, and its specific implementation principle will explain in the back.

In a preferred embodiment, the filter circuit on PCB is specially LC filter circuit, and the conductive connecting between the PLL of IC device power pin and LC filter circuit is arranged to helix; Meanwhile, this helix can be positioned at the internal layer wiring layer of pcb board, such as middle wiring layer etc., in practical application, can, according to the design of PCB, helix be laid in suitable wiring layer.Particularly, connecting line between LC filter circuit on pcb board and the PLL power pin of IC device can be designed to helix, concrete cabling mode is that top layer cabling is changed to pcb board internal layer through via hole 14 and walked helix, by via hole 122, change to skin again, be connected in PLL power pin 121.

To arranging in the utility model after helix, pcb board can describe the inhibition principle of power supply noise below.

In the PCB that the utility model provides, the helix magnetic force of laying is concentrated, and is equivalent to a certain size inductance, is equivalent to increase again one-level filtering after LC filter circuit, and it is to utilize planar spiral inductor theoretical.The inductance value that helical coil produces is in theory stronger, and the filter effect producing is better.The calculating of helical coil inductance value can be used spiral inductance theoretical calculation formula, specifically can be with reference to Wheeler equation:

${\mathrm{\μ}}_0{N}^2\frac{K_1{d}_{\mathrm{avg}}}{1+K_2\mathrm{\ρ}}$

In above formula: L is the size that helix produces inductance, and N is the number of turns, μ ₀for permeability of vacuum, μ 0=4 π * 10^-7 Henry/rice, K1, K2 are the coefficients relevant to shape, d _avg=(d _in+ d _out)/2, ρ=(d _out-d _in)/(d _in+ d _out), d wherein _infor helical coil interior diameter, d _outfor helical coil overall diameter, specifically referring to Fig. 4.Herein the form parameter of helix can also select square, hexagon, octangle etc., in the present embodiment, helix adopts square layout, K1=2.34, K2=2.75.The concrete inductance value of helical coil obtains accurate numerical value by electromagnetic field simulation software, and this is prior art, does not repeat them here.

Below in conjunction with concrete simulation process, elaborate the technique effect comparison of prior art and technical solutions of the utility model enforcement, this simulation process is with Fig. 2, and Fig. 3 is example:

In prior art, referring to Fig. 2, filtered power supply 21 connects the PLL power pin 22 of IC device by walking thick copper lines, in this scheme, because the inductance that direct-connected copper cash produces is minimum, can ignore, do not produce filter action, power supply only carries out one-level filtering by LC filter circuit, so in this scheme, the power supply noise of power supply is suppressed to limited in one's ability.The Fig. 2 of take carries out emulation as example, in this scheme, selected filter circuit is LC filter circuit, it is the magnetic bead of 2A that inductance L is selected rated current, it is 10uf and 2 electric capacity that size is 100nf that capacitor C is selected 2 sizes, usining this width-frequency response obtaining after by simulation software emulation as input parameter before and after the magnetic bead of filter circuit should be as shown in Figure 5, and noise inhibiting ability is about 60dB;

In technical solutions of the utility model, referring to Fig. 3, in this scheme, due to helix have electric current by time can produce a certain size inductance, be equivalent to power supply has increased again one-level filtering after LC filter circuit carries out one-level filtering, so this scheme has clear improvement to the power supply noise inhibition ability of power supply VCC.The Fig. 3 of take carries out emulation as example, and in this scheme, selected filter circuit is comprised of LC filter circuit and spiral cabling.It is the magnetic bead of 2A that inductance L is selected rated current; Capacitor C is divided into two groups, and every group is selected respectively a size is that 10uf and another size are the electric capacity of 100nf; Selected spiral cabling, N=3, d _in=20mil, d _out=180mil, live width=20mil, distance between centers of tracks=10mil, the about 20nH of equivalent inductance obtaining, the about 30mohm of line impedence.Specifically connected mode is, the magnetic bead that rated current is 2A is connected in series with helix with after first group of capacitance series again, and helix is concatenated on another group electric capacity again, finally outputs to PLL power pin 34.In actual design, need to there be electric capacity at power pin place.Width-the frequency response that obtains the magnetic bead front and back of filter circuit after utilizing above selected parameter by simulation software emulation should be as shown in Figure 6, the about 90dB of noise inhibiting ability, and noise inhibiting ability has improved 30dB.

Through above-mentioned simulation process, those skilled in the art can have a clear understanding of scheme described in Fig. 3 can obviously improve the inhibition ability to power supply noise.

The foregoing is only preferred embodiment of the present utility model; not in order to limit the utility model; all within spirit of the present utility model and principle, any modification of making, be equal to replacement, improvement etc., within all should being included in the scope of the utility model protection.

Claims (5)

1. a printed circuit board (PCB), is provided with filter circuit and integrated circuit (IC) device on described printed circuit board (PCB), it is characterized in that:

Conductive connecting between the power pin of filter circuit and IC device is helix.

2. printed circuit board (PCB) as claimed in claim 1, is characterized in that, the conductive connecting between described filter circuit and the phase-locked loop pll power pin of IC device is helix.

3. printed circuit board (PCB) as claimed in claim 1 or 2, is characterized in that, described helix adopts square spiral.

4. printed circuit board (PCB) as claimed in claim 1 or 2, is characterized in that, described helix is positioned at the internal layer wiring layer of printed circuit board (PCB).

5. printed circuit board (PCB) as claimed in claim 1, is characterized in that, described filter circuit is LC filter circuit.

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