TWI452481B - Priented circuit board and layout method thereof - Google Patents

Description

Printed circuit board and wiring method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a printed circuit board manufacturing technique, and more particularly to a printed circuit board and a wiring method thereof for reducing crosstalk interference of differential pairs/differential mode transmission lines.

With the advancement of printed circuit board (PCB) fabrication technology, the size of the printed circuit board itself is getting smaller and smaller. Due to the design requirements, not only the number of circuit components disposed on the printed circuit board is increased, but also the signal transmission speed between the circuit components is increasing. Therefore, the differential signal with strong anti-interference ability is also It has been widely used in transmission lines on printed circuit boards for high-speed signal transmission.

However, if a large number of circuit components are laid out within a limited board area, the spacing between the transmission lines is bound to be shortened, causing crosstalk to occur between these transmission lines, thereby affecting transmission quality. . If the spacing between the transmission lines is increased, the area in which the circuit layout can actually be performed is reduced accordingly.

Therefore, under the premise of shortening the wiring area of the circuit and reducing the interference between the transmission lines, how to effectively distribute the differential mode transmission line on the printed circuit board is one of the important topics in the field.

The invention provides a printed circuit board and a wiring method thereof, which can calculate an optimal horizontal distance between two differential pairs through a mathematical model, and reduce crosstalk interference between the differential pairs.

The present invention provides a wiring method for a printed circuit board, the layout method comprising the following steps. The first signal layer, the first dielectric layer, and the second signal layer are disposed, wherein the first dielectric layer is disposed between the first signal layer and the second signal layer. The horizontal distance is calculated according to a plurality of parameters of the first signal layer, the first dielectric layer, the second signal layer, the first differential pair, and the second differential pair. And a first differential pair and a second differential pair are disposed to the first signal layer and the second signal layer, wherein a horizontal interval between the first differential pair and the second differential pair is the horizontal distance.

In an embodiment of the invention, calculating the horizontal distance comprises the following steps. And generating a crosstalk transfer formula and a crosstalk time domain transfer function according to the parameters of the first signal layer, the first medium layer, the second signal layer, the first differential pair, and the second differential pair. And calculating the horizontal distance according to the crosstalk transfer formula and the crosstalk time domain transfer function.

In an embodiment of the invention, the first differential pair and the second differential pair respectively comprise two transmission lines, and the generating the crosstalk transfer formula comprises the following steps. And inputting a plurality of test signals according to parameters of the first signal layer, the first medium layer, the second signal layer, the first differential pair, and the second differential pair to obtain an analog signal from one of the end points of the transmission lines Multiple inductive signals at either end of the transmission line. The frequency domain transfer matrix is calculated based on these test signals and these inductive signals. And, converting the frequency domain transfer matrix from the differential mode to the common mode to the mixed mode to obtain a crosstalk transfer formula from any end point to any end point.

In an embodiment of the invention, the first differential pair has a first end of the proximal end and a second end of the distal end in the hybrid mode, and the second differential pair has a proximal end in the hybrid mode a third end point and a fourth end point of the far end, and the first differential pair has a first transmission line having a first end point and a second end point in a differential mode-common mode, having a third end point and a a second transmission line of four endpoints, a second transmission line having a fifth end point and a sixth end point in the differential mode-common mode, and a fourth transmission line having a seventh end point and an eighth end point . And the crosstalk transfer formula of the first end of the first differential pair of the first differential pair to the proximal end of the third end of the second differential pair is:

Where K _{b_d3d1} is a crosstalk time domain transfer function of the first end of the first differential pair to the third end of the second differential pair in the hybrid mode, and K _bmn is a differential mode-common mode The crosstalk time domain coefficients of the nth end point to the mth end point of these transmission lines at the near end, m and n are positive integers.

In an embodiment of the invention, the crosstalk time domain coefficients of the nth end point to the mth end point of the transmission lines in the differential mode-common mode are:

Wherein, L _S is a self-inductance from the nth end to the mth end point, L _M is a mutual inductance of the nth end point to the mth end point, and C _S is a self-capacity of the nth end point to the mth end point, and L _M is the mutual capacitance of the nth endpoint to the mth endpoint.

In an embodiment of the invention, the crosstalk transfer formula of the first end of the first differential pair to the far end of the fourth end of the second differential pair is:

Where K _{f_d4d1} is a crosstalk time domain transfer function of the first end of the first differential pair to the fourth end of the second differential pair in the mixed mode, and K _fmn is a differential mode-common mode The crosstalk time domain coefficients of the nth to mth endpoints of these transmission lines at the far end.

In an embodiment of the invention, the crosstalk time domain coefficients of the nth end point to the mth end point of the transmission lines in the differential mode-common mode are at the far end:

In an embodiment of the invention, the parameter includes a first dielectric layer, a second dielectric layer between the first signal layer and the first ground layer, and a third between the second signal layer and the second ground layer. a height of the dielectric layer, a dielectric material coefficient of the first dielectric layer, the second dielectric layer, and the third dielectric layer, and a dielectric material attenuation coefficient, a first differential pair, and a line width of each of the two differential transmission lines And the horizontal spacing between the two transmission lines.

In another aspect, the present invention provides a printed circuit board including a first signal layer, a second signal layer, and a first dielectric layer, wherein the first signal layer includes a first differential pair. The second signal layer includes a second differential pair. And the first dielectric layer is disposed between the first signal layer and the second signal layer, wherein a horizontal distance between the first differential pair and the second differential pair is a horizontal distance, and the horizontal distance is determined by the first signal layer, A plurality of parameters of the first dielectric layer, the second signal layer, the first differential pair, and the second differential pair are calculated.

In an embodiment of the invention, the printed circuit board further includes a first ground layer, a second dielectric layer, a second ground layer, and a third dielectric layer, wherein the second dielectric layer is disposed on the first ground layer and Between the layers of a signal. The third dielectric layer is disposed between the second ground layer and the second signal layer. Please refer to the above description for the rest of the implementation details, and I will not repeat them here.

Based on the above, the printed circuit board and the wiring method thereof according to the present invention calculate the horizontal distance between the first differential pair and the second differential pair in the printed circuit board through the mathematical model and the relevant parameters of the printed circuit board, and The horizontal spacing of the two differential pairs is set to the calculated value when the circuit layout is performed, thereby reducing crosstalk interference between the differential pair/differential mode transmission lines.

The above described features and advantages of the present invention will be more apparent from the following description.

DETAILED DESCRIPTION OF THE INVENTION Reference will now be made in detail to the exemplary embodiments embodiments In addition, wherever possible, the elements and/ In addition, in the exemplary embodiments of the present invention, the first to eighth and the like are used to distinguish a plurality of components or components having similar functions or structures, and are not intended to limit the present invention.

In general, Broad-Side Edge-Coupling differential mode transmission lines are mainly placed in printed circuit boards and are commonly used to transmit high speed differential mode signals. In other words, the printed circuit board is usually designed with two ground layers and two signal layers, and the Broad-SideEdge-Coupling differential mode transmission lines are respectively disposed in the above two signal layers.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a printed circuit board according to an embodiment of the invention. As shown in FIG. 1, the printed circuit board 10 includes a first signal layer SL1, a second signal layer SL2, and a first dielectric layer ML1. The first signal layer SL1 includes a first differential pair DP1. The first differential pair DP1 further includes a first transmission line DP1a and a second transmission line DP1b. The second signal layer SL2 includes a second differential pair DP2. The second differential pair DP2 includes a third transmission line DP2a and a fourth transmission line DP2b.

In this embodiment, the first differential pair DP1 and the second differential pair DP2 are both used to transmit differential mode signals, but the invention is not limited thereto. In the embodiment of the present invention, the first differential pair DP1 and the second differential pair DP2 may also be used to transmit a common mode signal or a mixed mode signal. In the embodiment of the present invention, the first transmission line DP1a, the second transmission line DP1b, the third transmission line DP2a, and the fourth transmission line DP2b are Broad-Side Edge-Coupling differential mode transmission lines.

In another embodiment of the present invention, the printed circuit board 10 further includes a first ground layer G1, a second dielectric layer ML2, a second ground layer G2, and a third dielectric layer ML3. The second dielectric layer ML2 is disposed between the first ground layer G1 and the first signal layer SL1, and the third dielectric layer ML3 is disposed between the second ground layer G2 and the second signal layer SL2.

Referring again to FIG. 1, the horizontal distance D is in FIG. 1, with the horizontal distance between the first differential pair DP1 and the second differential pair DP2 being the horizontal distance D. It is worth mentioning that the horizontal distance D is one of the most important factors affecting the crosstalk between the first differential pair DP1 and the second differential pair DP2. The reason is as follows, generally, at different horizontal distances. D, the crosstalk signal between the first differential pair DP1 and the second differential pair DP2 due to electromagnetic induction will also be different. During the experiment, it is found that the two differential pairs will be at a certain distance. With minimal crosstalk interference, after the specific distance is exceeded, the two differential pairs can only be pulled far to a considerable distance to have less interference.

Therefore, as long as the correlation between the horizontal distance D, the first differential pair DP1, the second differential pair DP2, and the crosstalk interference signal can be found, it can be found in a limited space (printed circuit board 10) An optimum horizontal distance D between the differential pair DP1 and the second differential pair DP2. In the embodiment of the present invention, under the optimal horizontal distance D, the crosstalk interference signal between the first differential pair DP1 and the second differential pair DP2 is the smallest (near zero), so the transmission quality is also optimal.

However, in the past, when the circuit layout was carried out, the horizontal distance D can only be obtained by experimental manual verification, that is, the personnel can grasp the horizontal distance with their own experience, and there is no better simulation or calculation rule to calculate. The optimal horizontal distance D, if the personnel experience is insufficient, often increases the cost of time. In this manner, the embodiment of the present invention is based on a mathematical model, a computer simulation, or the like, according to the first signal layer SL1, the first dielectric layer ML1, the second signal layer SL2, the first differential pair DP1, and the second differential pair DP2. The parameters are used to calculate the horizontal distance D. In this way, the circuit layout can be integrated into the optimal horizontal distance D by using mathematical calculations, and manual simulation is not required in time, thereby improving the timeliness of circuit design. In detail, the horizontal distance D can be calculated from the following crosstalk transfer formula and crosstalk time domain transfer function. For the detailed calculation method flow, please refer to the following description.

2 is another schematic diagram of the printed circuit board 10 of FIG. 1 in differential mode-common mode, in accordance with an embodiment of the present invention. In the differential mode-common mode described in this embodiment, the printed circuit board 10 considers the differential mode or the common mode signal with two transmission lines of the differential pair. It should be noted that the printed circuit board 10 and the first differential pair DP1, the first transmission line DP1a, the second transmission line DP1b, the second differential pair DP2, the third transmission line DP2a, and the fourth transmission line DP2b are respectively equivalent to FIG. The printed circuit board 10 and the first differential pair DP1, the first transmission line DP1a, the second transmission line DP1b, the second differential pair DP2, the third transmission line DP2a, and the fourth transmission line DP2b are not described herein. In addition, the first transmission line DP1a includes a first end point P1 and a second end point P2, the second transmission line DP1b includes a third end point P3 and a fourth end point P4, and the third transmission line DP2a includes a fifth end point P5 and a sixth end Point P6, and the fourth transmission line DP2b includes a seventh endpoint P7 and an eighth endpoint P8.

As shown in FIG. 2, in the differential mode-common mode, it is assumed that the present embodiment provides test signals a1~a8 for the eight terminals P1~P8 of the printed circuit board 10, respectively, at this time due to the differential pair DP1. The crosstalk between DP2 will generate the inductive signal b1~b8 The inductive signal b1~b8 will be generated by the inductive test signals a1~a8. For example, when the test signal a1 is input to the first end point P1, the inductive signals b1 to b8 may be generated accordingly.

In addition, in this embodiment, the sensing matrix Bstd is calculated by computing the test matrix Astd and the frequency domain transfer matrix Sstd. Each element in the test matrix Astd is composed of a test signal ai (for example, a1~a8), and each element in the sensing matrix Bstd is composed of an inductive signal bj (for example, b1~b8), and the frequency domain transfer matrix Sstd is composed of The frequency domain transfer function Sji is composed, and i and j are positive integers of 1-8.

Specifically, the calculation matrix Bstd obtained by using the operational test matrix Astd and the frequency domain transfer matrix Sstd can be expressed by equation (2-1):

Bstd=Sstd×Astd (2-1)

among them,

Then, the present embodiment uses the computer software to simulate the transmission lines DP1a to DP2b and the test matrix Astd in the printed circuit board 10, thereby obtaining the sensing matrix Bstd. For example, the present embodiment simulates a transmission line DP1a~DP2b having a known physical characteristic by using a Simulation Program with Integrated Circuit Emphasis (HSPICE), and simulates an input test signal a1 at the end points P1 to P8. ~a8, you can get the sensing signal b1~b8. In other words, taking the test matrix Astd containing the test signal a1 as an example, assume that the test matrix Astd is:

After substituting the test matrix Astd into equation (2-1), the obtained sensing matrix Bstd is:

Then, through the HSPICE simulation, the generated inductive signals b1~b8 are substituted into the equation (2-2), that is, the inductive signals b1~b8 are substituted into b1=a1×S ₁₁ , b2=a1×S ₂₁ ...b8= In a1×S ₈₁ , the frequency domain transfer function S _j1 can be obtained (assuming the test signal a1 is known), where j=1~8. The remaining frequency domain transfer functions S _j2 ~S _j8 can be _{derived in} the same way.

As described above, in this embodiment, the differential mode - the common mode through a frequency domain transfer function S _ji with AI test signal, Pj can be determined corresponding to the j-th terminal BJ generated sensing signal, wherein i and j is A positive integer from 1 to 8. In other words, the sensing matrix Bstd can be obtained by the test matrix Astd and the frequency domain transfer matrix Sstd.

In order to convert the frequency domain transfer matrix Sstd from the differential mode to the common mode of FIG. 2 to a mixed mode (ie, treating each differential pair as a single transmission line to simultaneously consider differential and common mode signals) Transfer matrix, the printed circuit board in the mixed mode and its frequency domain transfer matrix are further described below with reference to FIG. 3, please refer to FIG.

3 is a schematic diagram of a printed circuit board 10 in a hybrid mode, in accordance with an embodiment of the present invention. As shown in FIG. 3, the printed circuit board 10 includes a first differential pair DP1 and a second differential pair DP2. The first differential pair DP1 and the second differential pair DP2 are respectively the same as the differential pair DP1 and the second differential pair DP2 in FIG. 2, and thus are not described herein again. In addition, in the hybrid mode, the first differential pair DP1 has a first end CP1 at the near end and a second end point CP2 at the far end, and the second differential pair DP3 has a third end CP3 at the near end and a far end. The fourth endpoint of the end is CP4.

Referring to FIG. 2 and FIG. 3 simultaneously, the first endpoint CP1 in FIG. 3 can be regarded as the endpoint after the first endpoint P1 and the third endpoint P3 of FIG. 2 are merged, and the second endpoint CP2 can be regarded as FIG. 2 The endpoints after the second endpoint P2 and the fourth endpoint P4 are merged, and the remaining endpoints CP3 and CP4 and so on.

In this embodiment, in the hybrid mode, the test signals a1~a8 and the inductive signals b1~b8 in FIG. 2 are respectively combined into a differential mode test signal ad1~ad4, a differential mode sensing signal bd1~bd4, and a common mode. Test signals ac1~ac4 and common mode sensing signals bc1~bc4. The first differential pair DP1 can be used to transmit differential mode test signals ad1~ad2, common mode test signals ac1~ac2, differential mode sensing signals bd1~bd2, and common mode sensing signals bc1~bc2. The second differential pair DP2 can be used to transmit the differential mode test signals ad3~ad4, the differential mode sensing signals bd3~bd4, the common mode test signals ac3~ac4, and the common mode sensing signals bc3~bc4.

Referring to FIG. 2 and FIG. 3 simultaneously, taking the differential mode sensing signal ad1 as an example, after the test signals a1 and a3 are converted by the linear algebra substrate, the differential mode test signal ad1 in the differential mode can be obtained, and the differential mode can be obtained. The test signal ad1 is expressed in the following mathematical formula:

among them, A substrate for linear algebra substrate conversion. And so on, the remaining differential mode test signals ad2~ad4, differential mode sensing signals bd1~bd4, common mode test signals ac1~ac4 and common mode sensing signals bc1~bc4 can be expressed as:

Referring again to FIG. 3, in the hybrid mode, the differential mode test signals ad1 to ad4 and the common mode test signals ac1 to ac4 are respectively given to the terminals CP1 to CP4 of the printed circuit board 10, and the differential mode sensing signals bd1 to bd4. And the common mode sensing signals bc1~bc4 are generated by the differential mode test signals ad1~ad4 and the common mode test signals ac1~ac4. For example, when the differential mode test signal ad1 is input to the first terminal CP1, the differential mode test signals ad1 to ad4 and the common mode sensing signals bc1 to bc4 may be respectively generated.

In this embodiment, the mixed mode test matrix Bmm is calculated by calculating the mixed mode test matrix Amm and the frequency domain transfer matrix Smm in the mixed mode, wherein the mixed mode test matrix Amm is measured by the differential mode test signals ad1~ad4 and the common mode test signal ac1. ~ac4 is composed, and the mixed mode sensing matrix Bmm is composed of differential mode sensing signals bd1~bd4 and common mode sensing signals bc1~bc4. The frequency domain transfer matrix Smm in the mixed mode is composed of the frequency domain transfer function S _{uv in the} mixed mode, wherein u and v can be d1~d4 and c1~c4, respectively.

Specifically, in the embodiment, the method of calculating the mixed mode test matrix Amm and the frequency domain transfer matrix Smm in the mixed mode to obtain the mixed mode induction matrix Bmm can be expressed by the following equation (3-1):

Bmm=Smm×Amm -(3-1)

Among them, Bmm, Amm and Smm are:

Similarly, the mixed mode induction matrix Bmm can be easily obtained by analog transmission of the first differential pair DP1, the second differential pair DP2, and the mixed mode test matrix Amm in the known printed circuit board 10. For example, by using HSPICE to simulate the first differential pair DP1, the second differential pair DP2, and the differential mode test signals ad1~ad4 and the common mode test signals ac1~ac4 at the endpoints CP1~CP4, the differential mode can be obtained. The sensing signals bd1~bd4 and the common mode sensing signals bc1~bc4. Taking the mixed-mode test matrix Amm containing the differential mode test signal ad1 as an example, assume that the mixed-mode test matrix Amm is:

After substituting the mixed mode test matrix Amm into equation (3-1), the mixed mode induction matrix Bmm is obtained as:

Then, the differential mode sensing signals bd1~bd4 and the common mode sensing signals bc1~bc4 generated by the HSPICE simulation are substituted into the equation (3-2), that is, bd1~bd4 and bc1~bc4 are substituted into bd1=ad1×S _d1d1 and bd2. =ad1×S _d2d1 and so on until bc4=ad1×S _c4d1 (known as ad1), the frequency domain transfer function S _ud1 (v=d1) in the mixed mode can be obtained, where u=d1~d4 and c1~c4 . The frequency domain transfer functions S _ud2 ~S _ud4 (v=d2~d4) and S _uc1 ~S _uc4 (v=c1~c4) in the other mixed modes can be obtained by analogy.

In summary, in an embodiment of the present invention, the differential mode sensing signal and the common mode sensing signal bu can be obtained by transmitting the frequency domain transfer function S _uv and the differential mode test signal and the common mode test signal av in the mixed mode. , where u and v can be d1~d4 and c1~c4. In other words, the hybrid sensing matrix Bmm can be obtained by mixing the test matrix Amm and the frequency domain transfer matrix Smm in the mixed mode.

Furthermore, in order to find the relationship between the frequency domain transfer matrix Smm in the mixed mode and the frequency domain transfer matrix Sstd in the differential mode-common mode, the differential mode test signals ad1~ad4 and the differential mode sensing signal bd1 are obtained. ~bd4, the common mode test signals ac1~ac4 and the common mode sensing signals bc1~bc4 corresponding to the test signals a1~a8 and the inductive signals b7~b8 are respectively substituted into the mixed test matrix Amm and the mixed induction matrix Bmm, which are available The hybrid test matrix Amm is:

That is, Amm = M × Astd. And the hybrid induction matrix Bmm is:

That is, Bmm = M × Bstd. Where M is

Then, after substituting Amm=M×Astd and Bmm=M×Bstd into the equation (3-1), the frequency domain transfer matrix Smm in the mixed mode and the frequency domain transfer matrix Sstd in the differential mode-mix mode are obtained. The relationship is as follows:

^{Smm = M × Sstd × M -1} - (3-3)

Then, after substituting M and the frequency domain transfer matrix Sstd in the differential mode-mix mode described above into equation (3-3) and expanding, the mixed mode in the frequency domain transfer matrix Smm in the mixed mode can be obtained. The frequency domain transfer function S _uv corresponds to the frequency domain transfer function S _ji in each differential mode-mix mode in the frequency domain transfer matrix Sstd in the differential mode-mix mode (see below) Because the present invention is for the crosstalk interference problem of the differential mode signal on the differential mode transmission line, only the differential mode frequency domain transfer function S _d1d1 ~ S _d4d4 in the frequency domain transfer matrix Smm in the mixed mode is listed _here , and the rest The common mode related frequency domain transfer function is not discussed):

In the embodiment of the present invention, the differential mode frequency domain transfer function S _d1d1 ~ S _d4d4 can also be divided into a differential mode near-end crosstalk (Near-End Crosstalk) frequency domain transfer function and a differential mode far-end crosstalk (Far-End). Crosstalk) The frequency domain transfer function, for example, S _d3d1 is the differential mode near-end string audio domain transfer function, and S _d4d1 is the differential mode far-end string audio domain transfer function.

Referring to FIG. 3 again, the differential mode sensing signal bd3 generated by the differential mode test signal ad1 is a near-end crosstalk, and the differential mode sensing signal bd4 generated by the differential mode input signal ad1 is a far-end crosstalk. In particular, the differential analog near-end string audio domain used to convert the first endpoint CP1 of the first differential pair DP1 to the third endpoint CP3 of the proximal end of the second differential pair DP2 The transfer function S _d3d1 can be expressed by the following equation:

And a differential mode far-end string audio domain transfer function for converting the first-end CP1 of the first differential pair DP1 to the fourth-end CP4 of the far-end of the second differential pair DP2 S _d4d1 can be expressed by the following equation:

It should be noted here that although only the differential mode near-end string audio domain transfer function S _d3d1 and the differential mode far-end string audio domain transfer function S _d4d1 are defined in this embodiment, because the first differential pair DP1 and the first The two differentials have the same physical structure for DP2. Therefore, the crosstalk caused by the second differential pair DP2 to the first differential pair DP1 can directly compare the difference mode near-end string audio domain transfer function S _d3d1 and the differential mode far end. String audio domain transfer function S _d4d1 .

In addition, in order to correspond to the differential mode near-end string audio domain transfer function S _d3d1 and the differential mode far-end string audio domain transfer function S _d4d1 to the near-end crosstalk time domain transfer function and the far-end crosstalk time domain transfer function, first It is necessary to define crosstalk interference between multiple transmission lines in differential mode-common mode. Therefore, in order to analyze the physical characteristics of the transmission line, the transmission line is usually equivalent to resistance, inductance, conductance (Conductance). ) and the resistor-inductance conductance capacitor (RLGC) equivalent circuit composed of circuit components such as capacitors, please refer to Figure 4.

4 is a RLGC equivalent circuit diagram of a first differential pair DP1 or a second differential pair DP2 of the printed circuit board 10 of FIG. 1 according to an embodiment of the invention.

As shown in FIG. 4, taking the first differential pair DP1 in the differential mode-common mode, the first differential pair DP1 includes a first transmission line DP1a and a second transmission line DP1b, wherein the first transmission line DP1a and the first The two transmission lines DP1b are respectively the same as the first transmission line DP1a and the second transmission line DP1b in FIG. 1, and therefore will not be described herein. The near-end crosstalk interference signal V _near caused by the first transmission line DP1a to the second transmission line DP1b can be obtained by the following equation:

V _near =V _input ×K _b -(4-1)

Where K _b is a crosstalk time domain coefficient of the first end of the first transmission line DP1a to the third end of the second transmission line DP1b at the near end. In an embodiment of the invention, the near-end crosstalk time domain coefficient is:

The far-end crosstalk interference signal V _far can be obtained by the following equation:

Where K _f is the crosstalk time domain coefficient of the first end of the first transmission line DP1a to the fourth end of the second transmission line DP1b in the differential mode-common mode. In one embodiment of the present invention, the distal end of the time-domain crosstalk coefficient K _f is:

Wherein, the parameter V _input is the input voltage, the parameter T _r is the rise time of the input voltage, the parameter X is the transmission line length, the parameter L _S is the self inductance, the parameter L _M is the mutual inductance, and the parameter C _S is Self capacitance, parameter C _M is mutual capacitance, and parameter R is characteristic impedance.

To further extend the _near- end crosstalk signal V _near and the far-end crosstalk signal V _far caused by the first transmission line DP1a in the first differential pair DP1 to the second transmission line DP1b to the first differential pair in FIG. The near-end crosstalk signal and the far-end crosstalk signal interference between the DP1 and the second differential pair DP2, the following will be detailed in FIG. 5A and FIG. 5B for the interference between the differential pair and the far-end crosstalk signal. Description.

5A is a cross-sectional view of the printed circuit board 10 of FIG. 1 according to an embodiment of the invention, and FIG. 5B is a schematic diagram of the printed circuit board of FIG. 1 simulated by an analog software according to an embodiment of the invention. For the relationship between the generated near-end crosstalk signal/distal crosstalk signal and the horizontal distance between the differential pair, please refer to FIG. 5A and FIG. 5B simultaneously.

As shown in FIG. 5A, the printed circuit board 10 includes a first differential pair DP1 and a second differential pair DP2, wherein the first differential pair DP1 and the second differential pair DP2 are respectively identical to the first differential in FIG. DP1 and the second differential pair DP2 are not described here.

The vertical cross-sectional view of the printed circuit board 10 includes a plurality of parameters, such as the height H1 of the first dielectric layer, the height H2 of the second dielectric layer, the height H3 of the third dielectric layer, and the maximum level of the transmission lines DP1a, DP1b, DP2a, and DP2b. Line width W, difference between horizontal maximum line width and minimum line width of transmission lines DP1a, DP1b, DP2a and DP2b We, first dielectric layer dielectric material coefficient Er1, second dielectric layer dielectric material coefficient Er2, third dielectric layer Dielectric material coefficient Er3, first dielectric layer dielectric material attenuation coefficient Df1, second dielectric layer dielectric material attenuation coefficient Df2, third dielectric layer dielectric material attenuation coefficient Df3, vertical lines of transmission lines DP1a, DP1b, DP2a and DP2b The width t, the horizontal spacing S1 between the transmission lines DP1a and DP1b, the horizontal spacing S2 between the transmission lines DP2a and DP2b, and the horizontal spacing D between the first differential pair DP1 and the second differential pair DP2.

In the present embodiment, given H1=10 mil (thousandth of a mile), H2=4 mil, H3=4 mil, W1=W2=5 mil, We=0, Er1=4.2, Er2=3.8, Er3=3.8, Df1=Df2=Df3=0.022, t=1.3mil, S1=S2=6.5mil, and d=0~20mil are used as environmental parameters in the HSPICE simulation, and the invention is not limited thereto.

Referring to FIG. 5B, the HSPICE and the plurality of parameters in FIG. 5A are utilized to simulate the first differential pair DP1 and the second differential pair DP2 in the printed circuit board 10 at different horizontal distances D (or horizontal separation distances). Observing changes of the near-end crosstalk signal V _{d3d1_near} and the far-end crosstalk signal V _{d4d1_far} of the first differential pair DP1 to the second differential pair DP2. The square diagram represents the voltage level of the near-end crosstalk signal V _{d3d1_near} , and the diamond diagram represents the voltage level of the selected end crosstalk signal V _{d4d1_far} .

As shown in FIG. 5B, when the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is zero, the near-end crosstalk signal between the first differential pair DP1 and the second differential pair DP2 V _{d3d1_near} and the far-end crosstalk signal V _{d4d1_far are} large (about _{100 mils} ). When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is gradually increased from zero to 10~10.1 mil, the near-end crosstalk signal _{Vd3d1_near} and the far-end crosstalk signal _{Vd4d1_far} gradually become smaller. When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10~10.1 mil, the near-end crosstalk signal _{Vd3d1_near} and the far-end crosstalk signal _{Vd4d1_far are the} smallest (near zero). When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is gradually increased from 10.1 mil, the near-end crosstalk signal V _{d3d1_near} and the far-end crosstalk signal V _{d4d1_far} gradually become larger. In other words, as shown in FIG. 5B, the optimal horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10~10.1 mil, because at this horizontal distance D, the near-end crosstalk signal V _{d3d1_near} And the far end crosstalk signal V _{d4d1_far is the} smallest.

The following derivation of the differential mode near-end string audio domain transfer function S _d3d1 and the differential mode far-end string audio domain transfer function S _{d4d1 will} continue to derive the near-end crosstalk time domain transfer function (differential mode near-end crosstalk time domain) The transfer function) and the far-end crosstalk time domain transfer function (differential mode far-end crosstalk time domain transfer function), please refer to FIG. 6A.

FIG. 6A is a RLGC equivalent circuit diagram of a first differential pair DP1 and a second differential pair DP2 of the printed circuit board 10 of FIG. 1 according to an embodiment of the invention. As shown in FIG. 6A, the RLGC equivalent circuits of the first differential pair DP1 and the second differential pair DP2 are respectively identical to the RLGC equivalent circuit of the first differential pair DP1 or the second differential pair DP2 in FIG.

In this embodiment, firstly, according to the embodiment of FIG. 3, the first endpoint CP1 for converting the near end of the first differential pair DP1 is caused by the third endpoint CP3 of the proximal end of the second differential pair DP2. The differential mode near-end string audio domain transfer function S _d3d1 or equation (3-4) of the crosstalk interferes, by linear transformation, the first end of the first differential pair DP1 to the third end of the second differential pair The near-end crosstalk transfer formula is set to:

Where K _{b_d3d1} is the crosstalk time domain transfer function of the first end point CP1 of the first differential pair DP1 to the third end point CP3 of the second differential pair DP2 in the hybrid mode, and K _bmn (for example , K _b51 , K _b71 , K _b53 and K _b73 ) are the crosstalk time domain coefficients of the nth end point to the mth end point of the plurality of transmission lines in the differential mode-common mode, wherein m and n are positive Integer.

In an embodiment of the present invention, the crosstalk time domain coefficient K _bmn of the nth end point to the mth end point of the plurality of transmission lines in the differential mode-common mode is:

Wherein, the parameter L _S is the self-inductance of the nth end point to the mth end point, the parameter L _M is the mutual inductance of the nth end point to the mth end point, and the parameter C _S is the self of the nth end point to the mth end point. The capacitance and the parameter C _M are mutual capacitances from the nth end to the mth end point, and m and n are positive integers.

On the other hand, the crosstalk caused by the first endpoint CP1 for converting the near end of the first differential pair DP1 to the fourth endpoint CP4 of the far end of the second differential pair DP2 according to the embodiment of FIG. The differential mode far-end string audio domain transfer function S _d4d1 or equation (3-5) transmits the first end of the first differential pair DP1 to the far end of the fourth end of the second differential pair DP2 by linear transformation The crosstalk transfer formula is set to:

Where K _{f_d4d1} is a crosstalk time domain transfer function of the first end point CP1 of the first differential pair DP1 to the fourth end point CP4 of the second differential pair DP2 in the mixed mode, and K _fmn (for example _{, K f61, K f81, K} f63 and K _f83) differential mode - a plurality of common mode in the n-th end of the transmission line to the m-end crosstalk at the proximal end of the time domain coefficients, where m, n are positive Integer.

In an embodiment of the present invention, the crosstalk time domain coefficient K _fmn of the nth end point to the mth end point of the plurality of transmission lines in the differential mode-common mode is:

Referring to FIG. 6B, FIG. 6B illustrates a near-end crosstalk time domain transfer function and a far-end crosstalk time domain transfer function and a differential pair in the printed circuit board 10 of FIG. 1 according to an embodiment of the invention. A horizontal distance relationship diagram in which the square representation represents the value of the near-end crosstalk time domain transfer function _{Kb_d3d1} and the diamond representation represents the value of the far end crosstalk time domain transfer function _{Kf_d4d1} .

In FIG. 6B, according to equations (6-1), (6-2), (6-3), (6-4), and RLGC of the first differential pair DP1 and the second differential pair DP2 in FIG. 6A, etc. The plurality of parameters of the circuit are used to calculate the first differential pair DP1 and the second differential pair DP2 in the printed circuit board 10 at different horizontal distances D (or horizontally spaced distances), the first differential pair in the hybrid mode The first end point CP1 of DP1 to the third end point CP3 of the second differential pair DP2 is at the near end of the crosstalk time domain transfer function K _{b_d3d1} and is the first end point CP1 of the first differential pair DP1 in the hybrid mode The change to the crosstalk time domain transfer function _{Kf_d4d1} at the far end of the fourth terminal CP4 of the second differential pair DP2.

Referring to FIG. 6A and FIG. 6B simultaneously, when the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is zero, the calculated values of K _{b_d3d1} and K _{f_d4d1} are large (K _{b_d3d1} is approximately 9 × 10 ¹⁰ , K _{f_d4d1} is about 2 × 10 ² ). When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is gradually increased from zero to 10 to 10.1 mil, the calculated K _{b_d3d1} and K _{f_d4d1} are gradually reduced. When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10 to 10.1 mil, the calculated K _{b_d3d1} and K _{f_d4d1 are the} smallest (near zero). When the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is gradually increased from 10.1 mil, the calculated K _{b_d3d1} and K _{f_d4d1 are} gradually increased.

In other words, since K _{b_d3d1 is} proportional to the differential mode near-end string audio domain transfer function S _d3d1 , and K _{f_d4d1 is} proportional to the differential mode far-end string audio domain transfer function S _d3d1 . That is, the smaller the K _{b_d3d1 is, the} smaller the near-end crosstalk signal V _{d3d1_near is} , and the smaller the far-end crosstalk signal V _{d4d1_far is, the} smaller the far-end crosstalk signal V _{d4d1_far} is. Therefore, as shown in FIG. 6B, the optimum horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10 to 10.1 mil, because when D is 10 to 10.1 mil, K _{b_d3d1} and V _{d4d1_far are} minimum. .

Referring to FIG. 5B and FIG. 6B at the same time, it is worth mentioning that, in FIG. 5B and FIG. 6B, the optimal horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10~10.1. Mil. In more detail, in FIG. 5B and FIG. 6B, when the horizontal distance D between the first differential pair DP1 and the second differential pair DP2 is 10 mil, the far-end crosstalk signal V _{d4d1_far} and the far-end string whereas when the first differential pair DP1 and the second differential pair DP2 between the horizontal distance D is 10.1mil, near-end crosstalk and near-end signal _V d4d1_near crosstalk; time-domain noise transfer function _K f_d4d1 minimum average The domain transfer function K _{b_d4d1} is the smallest, so that different horizontal distances D can be selected according to actual needs while wiring the printed circuit board, and the invention is not limited thereto.

FIG. 7 is a schematic flow chart of a method for laying out a printed circuit board according to an embodiment of the invention. Please refer to FIG. 7. In FIG. 7, the layout method of the printed circuit board is started in step S720.

In step S720, a first signal layer, a first dielectric layer and a second signal layer are provided, wherein the first dielectric layer is disposed between the first signal layer and the second signal layer.

In step S740, a plurality of parameters of the first signal layer, the first medium layer, the second signal layer, the first differential pair, and the second differential pair are used to calculate a horizontal distance.

In step S760, the first differential pair and the second differential pair are disposed to the first signal layer and the second signal layer, wherein the horizontal interval between the first differential pair and the second differential pair is a horizontal distance. In an embodiment of the invention, the optimal horizontal distance between the differential pairs is 10 to 10.1 mil, and the invention is not limited thereto. In an embodiment of the invention, the horizontal distance between the differential pairs may also be adjusted as needed.

FIG. 8 is a schematic flow chart of a method for laying out a printed circuit board according to another embodiment of the present invention. In FIG. 8, the method of laying out the printed circuit board of the method begins in step S720. It should be noted that steps S720 and S760 are the same as steps S720 and S760 in FIG. 7, respectively, and therefore only steps S842 and S844 are described herein.

In step S842, a crosstalk transfer formula and a crosstalk time domain transfer function are generated according to the plurality of parameters of the first signal layer, the first medium layer, the second signal layer, the first differential pair, and the second differential pair.

In an embodiment of the present invention, the method for generating a crosstalk transfer formula and a crosstalk time domain transfer function may utilize a first signal layer, a first medium layer, a second signal layer, a first differential pair, and a second differential The plurality of parameters of the pair inputs a plurality of test signals from one of the plurality of transmission lines, and obtains a plurality of sensing signals at either end of the transmission lines. Calculate the frequency domain transfer matrix based on the test signal and the inductive signal, and convert the frequency domain transfer matrix from the differential mode to the common mode to the mixed mode to obtain the crosstalk transfer formula from any end point to any end point and the crosstalk time domain. Transfer function.

Referring to FIG. 6, in an embodiment of the present invention, the crosstalk transfer formula of the near end of the first end point CP1 of the first differential pair DP1 to the third end point CP3 of the second differential pair DP2 is:

Where K _{b_d3d1} is a crosstalk time domain transfer function of the first end point CP1 of the first differential pair DP1 to the third end point CP3 of the second differential pair DP2 in the hybrid mode, and K _bmn is a differential mode - The crosstalk time domain coefficients of the nth end point to the mth end point of the plurality of transmission lines in the common mode, wherein m and n are positive integers. The crosstalk transfer formula of the first differential pair DP1 to the far end of the fourth endpoint CP4 of the second differential pair DP2 is:

Where K _{f_d4d1} is a crosstalk time domain transfer function of the first end point CP1 of the first differential pair DP1 to the fourth end point CP4 of the second differential pair DP2 in the mixed mode, and K _fmn is a differential mode - The crosstalk time domain coefficient of the nth end point to the mth end point of the plurality of transmission lines in the common mode, wherein m and n are positive integers.

In step S844, the horizontal distance is calculated according to the crosstalk transfer formula and the crosstalk time domain transfer function.

For the above method, sufficient teaching, suggestion and implementation description can be obtained from the above embodiments, and details are not described herein again.

In summary, the printed circuit board and the wiring method thereof according to the present invention calculate the horizontal distance between the first differential pair and the second differential pair in the printed circuit board through the mathematical model and the relevant parameters of the printed circuit board. And setting the horizontal spacing of the two differential pairs to the calculated value when performing circuit layout, thereby reducing crosstalk interference between the differential pair/differential mode transmission lines.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10. . . A printed circuit board

A1~a8. . . Test signal

B1~b8. . . Inductive signal

Ac1~ac4. . . Common mode test signal

Ad1~ad4. . . Differential mode test signal

Bc1~bc4. . . Common mode sensing signal

Bd1~bd4. . . Differential mode signal

CP1~CP4, P1~P8. . . End point

D. . . Horizontal spacing between differential pairs

Df1~Df3. . . Dielectric material attenuation coefficient

DP1. . . First differential pair

DP1a. . . First transmission line

DP1b. . . Second transmission line

DP2. . . Second differential pair

DP2a. . . Third transmission line

DP2b. . . Fourth transmission line

Er1~Er3. . . Dielectric material coefficient

G1. . . First ground plane

G2. . . Second ground plane

H1~H3. . . Dielectric layer height

ML1. . . First dielectric layer

ML2. . . Second dielectric layer

ML3. . . Third dielectric layer

R. . . Characteristic group resistance

S1, S2. . . Horizontal spacing between transmission lines

t. . . Transmission line vertical height

V _input . . . Input signal

V _near . . . Near-end crosstalk signal

V _far . . . Far-end crosstalk signal

W1, W2. . . Transmission line width

We. . . Transmission line width difference

X. . . Transmission line length

1 is a schematic diagram of a printed circuit board in accordance with an embodiment of the present invention.

2 is another schematic diagram of the printed circuit board of FIG. 1 in a differential mode-common mode according to an embodiment of the invention.

3 is a schematic diagram of a printed circuit board in a hybrid mode according to an embodiment of the invention.

4 is a RLGC equivalent circuit diagram of a first differential pair or a second differential pair of the printed circuit board of FIG. 1 in accordance with an embodiment of the present invention.

FIG. 5A is a vertical cross-sectional view of the printed circuit board of FIG. 1 according to an embodiment of the invention.

FIG. 5B is a diagram showing the relationship between the near-end crosstalk signal generated by the analog circuit simulation of the printed circuit board of FIG. 1 and the horizontal distance between the far-end crosstalk signal and the differential pair, according to an embodiment of the invention. .

6A is an RLGC equivalent circuit diagram of a first differential pair and a second differential pair of the printed circuit board of FIG. 1 according to an embodiment of the invention.

6B illustrates the horizontal distance between the near-end crosstalk time domain transfer function and the far-end crosstalk time domain transfer function and the differential pair in the printed circuit board 10 of FIG. 1 in accordance with an embodiment of the present invention. relation chart.

FIG. 7 is a schematic flow chart of a method for laying out a printed circuit board according to an embodiment of the invention.

FIG. 8 is a schematic flow chart of a method for laying out a printed circuit board according to another embodiment of the present invention.

10. . . A printed circuit board

DP1. . . First differential pair

DP1a. . . First transmission line

DP1b. . . Second transmission line

DP2. . . Second differential pair

DP2a. . . Third transmission line

DP2b. . . Fourth transmission line

G1. . . First ground plane

G2. . . Second ground plane

ML1. . . First dielectric layer

ML2. . . Second dielectric layer

ML3. . . Third dielectric layer

D. . . Horizontal distance

Claims (8)

A method for arranging a printed circuit board includes: providing a first signal layer, a first dielectric layer, and a second signal layer, wherein the first dielectric layer is disposed between the first signal layer and the second signal layer Calculating a horizontal distance according to the plurality of parameters of the first signal layer, the first dielectric layer, the second signal layer, a first differential pair, and a second differential pair, wherein the parameters include the first a dielectric layer, a second dielectric layer between the first signal layer and a first ground layer, and a third dielectric layer between the second signal layer and a second ground layer, the first medium The dielectric material coefficient of the layer, the second dielectric layer and the third dielectric layer and the dielectric material attenuation coefficient, the first differential pair, and the respective line widths of the two transmission lines of the second differential pair and the two transmission lines a horizontal spacing therebetween; and setting the first differential pair and the second differential pair to the first signal layer and the second signal layer according to the horizontal distance, wherein the first differential pair to the second difference The horizontal distance between the moving pairs is the horizontal distance. The method of claim 1, wherein calculating the horizontal distance comprises: following the first signal layer, the first dielectric layer, the second signal layer, the first differential pair, and the second The parameters of the differential pair generate a crosstalk transfer formula and a crosstalk time domain transfer function; and calculate the horizontal distance according to the crosstalk transfer formula and the crosstalk time domain transfer function. The layout method of claim 2, wherein the first differential pair and the second differential pair respectively comprise two transmission lines, and generating the crosstalk transfer formula comprises the following steps: according to the first signal The parameters of the layer, the first dielectric layer, the second signal layer, the first differential pair, and the second differential pair are input to a plurality of test signals from one of the endpoints of the transmission lines. And obtaining a plurality of sensing signals of any one of the end points of the transmission lines; calculating a frequency domain transfer matrix according to the test signals and the sensing signals; and converting the frequency domain transfer matrix from a differential mode to a common mode to a hybrid Pattern to get the crosstalk transfer formula from either endpoint to either endpoint. The layout method of claim 3, wherein the first differential pair has a first end of the first end and a second end of the far end in the hybrid mode, the second difference Moving a third end point having a near end in the mixed mode and a fourth end point of the far end, and the first differential pair has the first end of the first end and the first end in the differential mode-common mode a first transmission line of the two endpoints, a second transmission line having a third end point and a fourth end point, the second differential pair having a fifth end point and a sixth end point in the differential mode-common mode a third transmission line, a fourth transmission line having a seventh end point and an eighth end point, and the first end point of the first differential pair to the third end point of the second differential pair The crosstalk transfer formula at the end is: Where K _{b_d3d1} is a near-end crosstalk time domain transfer function of the first end point of the first differential pair to the third end of the second differential pair in the mixed mode, and K _bmn is a differential mode a cross-talk time domain coefficient of the near-end from the nth end to the mth end of the transmission line in the common mode, where m and n are positive integers. The layout method of claim 4, wherein the crosstalk time domain coefficients of the nth end point to the mth end point of the transmission lines in the differential mode-common mode are: Wherein, L _S is a self-inductance from the nth end to the mth end point, L _M is a mutual inductance of the nth end point to the mth end point, and C _S is a self-capacity of the nth end point to the mth end point, and L _M is the mutual capacitance of the nth endpoint to the mth endpoint. The layout method of claim 4, wherein the crosstalk transfer formula of the first end point of the first differential pair to the far end of the fourth end point of the second differential pair is: Where K _{f_d4d1} is a crosstalk time domain transfer function of the first end point of the first differential pair to the far end of the second differential pair in the mixed mode, K _fmn is a differential mode a cross-talk time domain coefficient at the far end from the nth end to the mth end of the transmission lines in the common mode. The layout method according to claim 6, wherein the crosstalk time domain coefficients of the nth end point to the mth end point of the transmission lines at the far end in the differential mode-common mode are: A printed circuit board comprising: a first signal layer comprising a first differential pair; a second signal layer comprising a second differential pair; and a first dielectric layer disposed on the first signal layer Between the second signal layers, wherein a horizontal distance between the first differential pair and the second differential pair is a horizontal distance, and the horizontal distance is from the first signal layer, the first dielectric layer, The second signal layer, the first differential pair, and the plurality of parameters of the second differential pair are calculated, wherein the parameters include the first dielectric layer, the first signal layer, and a first ground layer a second dielectric layer and a third dielectric layer between the second signal layer and a second ground layer, a dielectric of the first dielectric layer, the second dielectric layer, and the third dielectric layer a material coefficient and a dielectric material attenuation coefficient, a first differential pair, and a line width of each of the two transmission lines in the second differential pair and a horizontal spacing between the two transmission lines.