CN101593612A - A kind of planar micro-strip inductance coil and preparation method thereof - Google Patents

Abstract

The present invention relates to a kind of planar micro-strip inductance coil and preparation method thereof, purpose provides that a kind of area occupied is little, cost of manufacture is low, the accurate planar micro-strip inductance coil of inductance value and manufacture method.A kind of planar micro-strip inductance coil comprises printed circuit board (PCB) and deposited copper strips, and described planar micro-strip inductance coil is attached on the printed circuit board (PCB) for deposited copper strips encompasses some circle circular planar spiral wire shaped.Manufacture method comprises: for the characteristic impedance value Z of the microstrip line of needs ₀, select the pcb board material, determine DIELECTRIC CONSTANT _r, calculate the phase velocity v of strip line _pAnd wavelength X; In computer, determine the deposited copper coil of benchmark spirality, and on the pcb board that is etched in, measure its real characteristic impedance and sense value; Retrodict and revise from characteristic impedance, accurately the benchmark computing formula of value felt and characteristic impedance recalculates the width w and the wavelength X of applying copper strips according to formula; The spiral micro-strip circle is distributed on the selected pcb board, and etching is come out.

Description

A kind of planar micro-strip inductance coil and preparation method thereof

Technical field

The present invention relates to a kind of inductance coil, particularly a kind of planar micro-strip inductance coil on the pcb board and preparation method thereof that is arranged on.

Background technology

At present, when needs used the accurate inductance of low value, the way that industry is current mainly was: one. use the inductance semiconductor chip of approaching current requirements of nominal value; Two are to use the snakelike microstrip line that is etched on the printed substrate to realize little inductance.The principal disadvantage of above-mentioned first kind of scheme is that cost is higher, needs to consume the raw material of volume simultaneously.Little value inductance is as main element in the radiofrequency signal circuit design, and use is quite extensive and consumption is very big.If all use the inductance chip, product cost can be quite high and be consumed a large amount of semiconductor source materials.Next is because the inductance sense value that is solidificated in the semiconductor chip is all determined, that is to say, and the inductance that can not provide sense to be worth complete realistic demand according to actual engineering, and can only select usability value immediate alternative.If in design, use the inductance chip of approximate sense value repeatedly, can cause the final technical parameter index of product to depart from original design greatly and be difficult to and debug.Adopt above-mentioned second kind of scheme cost to be greatly diminished, excessive but the problem brought is the area of busy line plate thereupon.Usually little value inductance of design need be around long microstrip line, if use serpentine, the serpentine that certainly will design can be long.In present design of electronic products more and more compacter today, just need take on the pcb board area iff design above a singlechip chip with regard to an inductance, with regard to the aesthetic property of the economy of its design, product, obviously be can not be received.Simultaneously because the design of serpentine, radiofrequency signal in serpentine bilevel signal flow to just in time opposite, when radiofrequency signal flows in microstrip line, can produce bigger mutual inductance effect, cause the inductor design value and the actual value of microstrip line to occur deviating from more greatly, cause serious debug difficulties.

Summary of the invention

The objective of the invention is to overcome the defective of prior art, provide that a kind of area occupied is little, cost of manufacture is low, inductance value is etched in the planar micro-strip inductance coil on the printed substrate accurately, and the manufacture method of this inductance coil.

The technical scheme that realizes the foregoing invention purpose is: a kind of planar micro-strip inductance coil, comprise printed circuit board (PCB) and deposited copper strips, and described planar micro-strip inductance coil is attached on the printed circuit board (PCB) for deposited copper strips encompasses some circle circular planar spiral wire shaped.

The present invention is by becoming the mode of helical coil to be etched on the PCB wiring board little value inductor design, with very little design area, reach the function of efficient little charged sense, owing to the annular principle of helix, the mutual inductance effect of radiofrequency signal when flowing has been greatly diminished simultaneously.And the spiral charged sense that declines is the deposited copper strips that is etched on the pcb board, does not almost increase cost and avoided raw-material a large amount of consumption in actual production, is a kind of low cost, high efficiency and accurate little charged sense.

The manufacture method of planar micro-strip inductance coil of the present invention comprises the following steps:

(1) for the characteristic impedance value Z of the microstrip line of needs ₀, select the pcb board material, determine the DIELECTRIC CONSTANT of pcb board _r, according to formula

$A=2\mathrm{\π}\frac{Z_0}{Z_f}\sqrt{\frac{{\mathrm{\ϵ}}_r+1}{2}}+\frac{{\mathrm{\ϵ}}_r-1}{{\mathrm{\ϵ}}_r+1}(0.23+\frac{0.11}{{\mathrm{\ϵ}}_r})---\left(e\right)$

Draw the value of coefficient A,

According to $\frac{w}{h}=\frac{8e^A}{e^{2A}-2}---\left(d\right)$

Obtaining microstrip line characteristic impedance figure determines approximate

Ratio,

According to ${\mathrm{\ϵ}}_{\mathrm{eff}}=\frac{{\mathrm{\ϵ}}_r+1}{2}+\frac{{\mathrm{\ϵ}}_r-1}{2}[{(1+12\frac{h}{w})}^{-t/2}+0.04{(1-\frac{w}{h})}^2]---\left(b\right)$

Obtain effective dielectric constant ε _Eff

Wherein, w is the width of microstrip line, and h is the PCB substrate thickness, ε _rBe the dielectric constant of pcb board, t is a copper thickness, $Z_f=\sqrt{{\mathrm{\μ}}_0/{\mathrm{\ϵ}}_0}=376.8\mathrm{\Ω}$ It is wave impedance at free space;

(2) according to acquisition

Ratio, and then obtain the width w that applies copper strips;

(3) according to the effective dielectric constant ε that obtains _EffCalculate the phase velocity v of strip line _pAnd wavelength X; Wherein $\mathrm{\λ}=\frac{v_p}{f}=\frac{c}{f\sqrt{{\mathrm{\ϵ}}_{\mathrm{eff}}}}=\frac{{\mathrm{\λ}}_0}{\sqrt{{\mathrm{\ϵ}}_{\mathrm{eff}}}},---\left(c\right)$

C is the light velocity, and f is an operating frequency;

(4) in computer, after the spacing of definite certain specific adjacent deposited copper strips this deposited copper strips is elongated and pitch of the laps, obtain the constant benchmark spirality of length and width and apply copper coil;

(5) on the pcb board that the deposited copper coil of this spiral is etched in, obtain its real characteristic impedance and its sense value by actual measurement;

(6) characteristic impedance that obtains suddenly according to previous step is retrodicted and is revised approximate formula $Z_0=\frac{\mathrm{<figure-callout\; id="2"\; label="Zf"\; filenames="A2009100292450011H1.png"\; state="\{\{state\}\}">Zf</figure-callout>}}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}\ln (8\frac{h}{w}+\frac{w}{4h})$ With ${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{2}[{(1+12\frac{h}{w})}^{-t/2}+0.04{(1-\frac{w}{h})}^2],$ Obtain the accurate sense value of spiral micro-strip circle of selected pcb board material and the benchmark computing formula SNC* of characteristic impedance, and recalculate the width w and the wavelength X of applying copper strips according to formula S NC*;

(7) the spiral micro-strip circle directly is distributed on the selected pcb board by computer software, etching is come out.

As a further improvement on the present invention, further comprise the following steps: in the step (6) most of inductance of sense value commonly used in the radio circuit design is etched into spiral micro-strip circle on the pcb board according to formula S NC*, the accuracy by induction checking SNC* is also done further correction.

Be described as follows for method of the present invention: the thickness t of our line conductor that has been shaped of supposition is compared with the thickness h of substrate and can be ignored (t/h＜0.005), and in this case, we only can utilize and wire sizes (w and h) and DIELECTRIC CONSTANT _rRelevant empirical equation.For narrow strip line w/h＜1 that we use, we obtain characteristic impedance:

$Z_0=\frac{\mathrm{<figure-callout\; id="2"\; label="Zj"\; filenames="A2009100292450011H1.png"\; state="\{\{state\}\}">Zj</figure-callout>}}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}\ln (8\frac{h}{w}+\frac{w}{4h})---\left(a\right)$

Wherein $Z_f=\sqrt{{\mathrm{\&mu;}}_0/{\mathrm{\&epsiv;}}_0}=376.8\mathrm{\&Omega;}$ Be wave impedance at free space, ε _EffBe the effective dielectric constant that provides by following formula:

${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{2}[{(1+12\frac{h}{w})}^{-t/2}+0.04{(1-\frac{w}{h})}^2]---\left(b\right)$

The characteristic impedance that top formula provides is an approximation, and whole

Not continuous functions in the scope.Fig. 2 and Fig. 3 have provided characteristic impedance and the effective dielectric constant that calculates with the expression formula of front.Z among the figure ₀And ε _EffDepict as

And ε _rFunction,

And ε _rParameter selection in the scope of typical actual interlock circuit value.

In the formula in front, effective dielectric constant is to see the dielectric constant that is full of circuit surrounding space uniform dielectric as, and uniform dielectric has substituted dielectric substrate and ambient air.Can calculate the phase velocity of strip line and derive the expression of wavelength with effective dielectric constant

$\mathrm{\&lambda;}=\frac{v_p}{f}=\frac{c}{f\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}=\frac{{\mathrm{\&lambda;}}_0}{\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}---\left(c\right)$

Wherein, c is the light velocity, and f is an operating frequency.Based on the purpose of design, can be according to given characteristic impedance Z ₀DIELECTRIC CONSTANT with substrate _rCalculate

Ratio.Suppose that line conductor is infinitely thin, can obtain following:

$\frac{w}{h}=\frac{8e^A}{e^{2A}-2}---\left(d\right)$

Wherein, coefficient A is:

$A=2\mathrm{\&pi;}\frac{Z_0}{Z_f}\sqrt{\frac{{\mathrm{\&epsiv;}}_r+1}{2}}+\frac{{\mathrm{\&epsiv;}}_r-1}{{\mathrm{\&epsiv;}}_r+1}(0.23+\frac{0.11}{{\mathrm{\&epsiv;}}_r})---\left(e\right)$

By the method for above-mentioned introduction, we can draw the width and the length lambda (unit: mil) of the deposited copper strips of the characteristic impedance that need reach certain numerical value.After the spacing of our definite certain specific adjacent deposited copper strips in computer this deposited copper strips is elongated and pitch of the laps, obtain the constant benchmark spirality of length and width and apply copper coil.We apply this spiral on the pcb board that copper coil is etched in, and obtain its real characteristic impedance and its sense value by actual measurement.And then retrodict and revise approximate formula mentioned above (a) and (b), obtained based on the accurate sense value of the spiral micro-strip circle of selected pcb board material and the benchmark computing formula SNC* of characteristic impedance.Then, we are etched into spiral micro-strip circle on the pcb board with most of inductance of sense value commonly used in the radio circuit design according to formula S NC*, and the accuracy by induction checking SNC* is also done further correction.Then utilize the PROTEL99 software on the computer, set up known sense value storehouse, be convenient in product design in the future, use at any time based on the spiral micro-strip circle on the selected pcb board.So far, we have obtained in the radio circuit design feature sense value storehouse and corresponding computing formula based on the spiral micro-strip circle of selected pcb board material.The spiral micro-strip circle that the sense value is suited the requirements directly is distributed on the selected pcb board by computer PROTELL99, washes the direct etching of plate company by PCB and comes out, and has just obtained the planar micro-strip inductance coil that suits the requirements.

Description of drawings

Fig. 1 is the parameter list diagrammatic sketch that applies copper strips and printed circuit board (PCB) among the present invention

Fig. 2 is the graph of a relation of microstrip line characteristic impedance and w/h among the present invention

Fig. 3 is the effective dielectric constant of differing dielectric constant among the present invention and the graph of a relation of w/h

Fig. 4 is the structural representation of embodiment of the invention midplane micro-strip inductance coil

Embodiment

Be described further below in conjunction with specific embodiment.

Embodiment 1

The radio circuit of a reality need have the characteristic impedance of 50 Ω, and the pcb board material of selecting for use is FR-4 type cheaply, applies the dimensional parameters of copper strips 2 and printed circuit board (PCB) 3 and represents as shown in Figure 1 the relative dielectric constant ε of printed circuit board (PCB) 3 _rBe 4.6, thickness t is 40mil, and the width that applies copper strips 2 is w.We need obtain applying the width w of copper strips, phase velocity v _pValue with wavelength X when the 2GHz.Concrete grammar is as follows:

Determine approximate according to microstrip line characteristic impedance figure (Fig. 2)

Ratio: select corresponding to ε _r=4.6 curve is found out Z ₀=50 Ω,

Approximation be 1.9.We can derive thus:

$A=2\mathrm{\&pi;}\frac{Z_0}{Z_f}\sqrt{\frac{{\mathrm{\&epsiv;}}_r+1}{2}}+\frac{{\mathrm{\&epsiv;}}_r-1}{{\mathrm{\&epsiv;}}_r+1}(0.23+\frac{0.11}{{\mathrm{\&epsiv;}}_r})=1.5583---\left(e\right)$

The result is brought into, can get

$\frac{w}{h}=\frac{8e^A}{e^{2A}-2}=1.8477---\left(d\right)$

Effective dielectric constant:

${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{2}{(1+12\frac{h}{w})}^{-t/2}=3.4575---\left(b\right)$

We can obtain thus

Ratio, and then obtain the width w=73.9mil that applies copper strips,

According to $\mathrm{\&lambda;}=\frac{v_p}{f}=\frac{c}{f\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}=\frac{{\mathrm{\&lambda;}}_0}{\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}---\left(c\right)$

The phase velocity that obtains microstrip line is 1.61 * 10 ⁸M/s and be 80.67mm in the effective wavelength of 2GHz.Strictly speaking, above-mentioned algorithm only is for the single deposited copper strips that concentrates on endless.In fact, in actual applications can be further by calculating the actual conditions of the deposited copper strips of adjacent and crooked finite length in the RF/MW computer-aided design system.

After the spacing of our definite certain specific adjacent deposited copper strips in computer this deposited copper strips is elongated and pitch of the laps, obtain the constant benchmark spirality of length and width and apply copper coil, this spiral is applied copper coil be etched on the pcb board of FR-4, obtain its real characteristic impedance and its sense value by actual measurement.

Suddenly the characteristic impedance that obtains according to previous step is retrodicted and is revised approximate formula mentioned above (a) and (b), obtains based on the accurate sense value of the spiral micro-strip circle of FR-4PCB sheet material and the benchmark computing formula SNC* of characteristic impedance again:

$Z_0=\frac{{\mathrm{<figure-callout\; id="2"\; label="Z\; f"\; filenames="A2009100292450011H1.png"\; state="\{\{state\}\}">Z</figure-callout>}}_f}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}\ln (8\frac{h}{w}+\frac{w}{4h})$

${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{3}[{(1+12\frac{h-1}{w})}^{-2t/3}+0.07{(1-\frac{2w}{h})}^2].$

Most of inductance of sense value commonly used in the radio circuit design is etched into spiral micro-strip circle on the FR-4 type pcb board according to formula S NC*, and the accuracy by induction checking SNC* is also done further correction.

Utilize the PROTEL99 software on the computer, set up known sense value storehouse, be convenient in product design in the future, use at any time based on the spiral micro-strip circle on the FR-4 pcb board.So far, we have obtained in the radio circuit design feature sense value storehouse and corresponding computing formula based on the spiral micro-strip circle of FR-4 type pcb board material.In the actual design of product, we directly are distributed in the spiral micro-strip circle that the sense value suits the requirements on the FR-4 type pcb board by computer PROTELL99, washing the direct etching of plate company by PCB comes out, just obtained the planar micro-strip inductance coil that suits the requirements as shown in Figure 4, planar micro-strip inductance coil 1 applies copper strips 2 by the circular planar spiral line that encompasses some circles and is etched in printed circuit board (PCB) 3 and constitutes.On FR-4 PCB printed substrate, get little band helical coil parameter and depend on different live widths, line-spacing, length and pitch of the laps mode.The pitch of the laps mode of little band spiral inductance in PROTEL99 software:

1, opens Protel 99SE software, a newly-built library file L.LIB;

2, double-click L.LIB and enter the library file editing interface;

3, click Arc (Any Angle) order in the menu bar Place drop-down menu, begin the picture semi arch, the terminal point of big arc is the starting point of corresponding little arc;

4, double-click semi arch, the correlation properties that can edit arc are as live width, radius, start angle etc.;

5, the characteristic of editing semi arch is waited in the live width that calculates according to simulation software, the number of turns, gap, and the center of circle of making sure to keep in mind all semi arches all is on same straight line, and the like, it is needed spiral-shaped just can to draw.

When the adjustable full frequency band programmable filter of design radio-frequency (RF) digital formula amplifier NTP8510/NTP8610, can use up to a hundred inductance with special characteristic impedance, we have utilized the spiral micro-strip circle to realize that cost is low, and the coil area occupied is little.For the sense value in the feature sense value storehouse that we set up, we can directly bring by computer PROTELL99 cloth on Virtual PC B, for those sense values not in the storehouse, we are by the benchmark computing formula SNC* winding turns of this inductance based on the little charged sense of benchmark spirality of retrodicting out, then be distributed on the other brassboard equally and test its actual value, checking and revising repeatedly obtains the microstrip line circle that needs then, puts into feature sense value storehouse thereafter and is provided with the back reference.Be used for the product circuit design simultaneously.Above-mentioned repeatedly EXPERIMENTAL DESIGN step obtains designing the radio frequency electric wiring board of finishing based on computer PROTELL99 software, transfers to PCB and washes the etching of plate company and come out, and obtains the PCB wiring board of the FR-4 type of final products.

Claims (7)

1, a kind of planar micro-strip inductance coil comprises printed circuit board (PCB) and deposited copper strips, it is characterized in that, described planar micro-strip inductance coil is attached on the printed circuit board (PCB) for deposited copper strips encompasses the circular snail wire shaped of some circles.

2, a kind of manufacture method of planar micro-strip inductance coil is characterized in that, comprises the following steps: as method

(1) for the characteristic impedance value Z of the microstrip line of needs ₀, select the pcb board material, determine the DIELECTRIC CONSTANT of pcb board _r, according to formula

$A=2\mathrm{\&pi;}\frac{Z_0}{Z_f}\sqrt{\frac{{\mathrm{\&epsiv;}}_r+1}{2}}+\frac{{\mathrm{\&epsiv;}}_r-1}{{\mathrm{\&epsiv;}}_r+1}(0.23+\frac{0.11}{{\mathrm{\&epsiv;}}_r})---\left(e\right)$

Draw the value of coefficient A,

According to $\frac{w}{h}=\frac{{8e}^A}{e^{2A}-2}---\left(d\right)$

Obtaining microstrip line characteristic impedance figure determines approximate

Ratio,

According to ${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{2}[{(1+12\frac{h}{w})}^{-t/2}+0.04{(1-\frac{w}{h})}^2]---\left(b\right)$

Obtain effective dielectric constant ε _Eff

Wherein, w is the width of microstrip line, and h is the PCB substrate thickness, ε _rBe the dielectric constant of pcb board, t is a copper thickness, $Z_f=\sqrt{{\mathrm{\&mu;}}_0/{\mathrm{\&epsiv;}}_0}=376.8\mathrm{\&Omega;}$ It is wave impedance at free space;

(2) according to obtaining

Ratio, and then obtain the width w that applies copper strips;

(3) according to the effective dielectric constant ε that obtains _EffCalculate the phase velocity v of strip line _pAnd wavelength X; Wherein

$\mathrm{\&lambda;}=\frac{v_p}{f}=\frac{c}{f\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}=\frac{{\mathrm{\&lambda;}}_0}{\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}},---\left(c\right)$

C is the light velocity, and f is an operating frequency;

(4) in computer, after the spacing of definite certain specific adjacent deposited copper strips this deposited copper strips is elongated and pitch of the laps, obtain the constant benchmark spirality of length and width and apply copper coil;

(5) on the pcb board that the deposited copper coil of this spiral is etched in, obtain its real characteristic impedance and its sense value by actual measurement;

(6) characteristic impedance that obtains suddenly according to previous step is retrodicted and is revised approximate formula $Z_0=\frac{Z_f}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}\ln (8\frac{h}{w}+\frac{w}{4h})$ With ${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{2}[{(1+12\frac{h}{w})}^{-t/2}+0.04{(1-\frac{w}{h})}^2],$ Obtain the benchmark computing formula SNC of characteristic impedance of accurate sense value of the spiral micro-strip circle of selected pcb board material ^*, and according to formula S NC ^*Again draw the width w and the wavelength X of applying copper strips;

(7) the spiral micro-strip circle directly is distributed on the selected pcb board by computer software, etching is come out.

3, planar micro-strip inductance coil according to claim 2 is characterized in that, further comprises the following steps: in the described step (6) to use most of inductance of sense value always according to formula S NC in the radio circuit design ^*Be etched into the spiral micro-strip circle on the pcb board, by induction checking SNC ^*Accuracy and do further correction.

4, planar micro-strip inductance coil according to claim 2 is characterized in that, described pcb board is a FR-4 type pcb board.

5, planar micro-strip inductance coil according to claim 2 is characterized in that, the computer software in described (7) is PROTELL99.

6, planar micro-strip inductance coil according to claim 2, it is characterized in that, the layout method of spiral micro-strip circle comprises in described (7): helical coil is made up of some semi arches, and the terminal point of big arc is the starting point of corresponding little arc, and the center of circle of all semi arches all is on same straight line.

7, planar micro-strip inductance coil according to claim 4 is characterized in that, the benchmark computing formula SNC of the characteristic impedance of the accurate sense value of described spiral micro-strip circle ^*For:

$Z_0=\frac{Z_f}{2\mathrm{\&pi;}\sqrt{{\mathrm{\&epsiv;}}_{\mathrm{eff}}}}\ln (8\frac{h}{w}+\frac{w}{4h})$

${\mathrm{\&epsiv;}}_{\mathrm{eff}}=\frac{{\mathrm{\&epsiv;}}_r+1}{2}+\frac{{\mathrm{\&epsiv;}}_r-1}{3}[{(1+12\frac{h-1}{w})}^{-2t/3}+0.07{(1-\frac{2w}{h})}^2].$

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