TWI622891B - Adjusting method for layout of signal transmission line - Google Patents

Abstract

The method for adjusting the layout of the signal transmission line includes: performing time domain reflection analysis on the signal transmission line, and obtaining time domain reflection analysis information; obtaining impedance discontinuous position in the signal transmission line according to time domain reflection analysis information, and corresponding adjacent impedance discontinuous position The reflection time is according to the operating frequency of the signal transmission line transmission signal at a set unit interval; the impedance discontinuous position is adjusted to obtain the first adjustment position, and the corresponding reflection time is substantially equal to an integral multiple of the unit interval.

Description

Signal transmission line layout adjustment method

The present invention relates to a method for adjusting a layout of a signal transmission line, and more particularly to a method for adjusting a layout of a signal transmission line that reduces the influence of a reflection phenomenon on signal transmission.

With the evolution of electronic component manufacturing technology and the needs of users, high-speed signal transmission has become an indispensable capability of electronic devices. However, as the complexity of the layout of the signal transmission line in the electronic device increases, the unevenness of the impedance generated in the single signal transmission line causes the transmission signal to generate a reflection during the transmission, and the reflection generated by the reflection action The signal will interfere with the transmission quality of the transmitted signal and even cause the transmission signal to go wrong.

Please refer to FIG. 1 , which illustrates an eye diagram of a transmission signal of a signal transmission line of the prior art. Among them, the observation signal is observed at one transmission period, and the reflected signal is generated at the position R1 of the reflection time TR1 from the origin. This reflected signal causes the eye diagram of the transmitted signal to be disturbed, which causes the eye shape to be broken and the eye height to be lowered, which affects the transmission quality of the signal.

The invention provides a layout adjustment method of a signal transmission line, which effectively reduces the influence of a reflection phenomenon occurring during signal transmission on signal transmission.

The method for adjusting the layout of the signal transmission line of the present invention comprises: performing time domain reflection analysis on the signal transmission line, and obtaining first time domain reflection analysis information; and obtaining a plurality of impedance discontinuous positions in the signal transmission line according to the first time domain reflection analysis information, And a plurality of first reflection times respectively corresponding to adjacent impedance discontinuous positions; the operating frequency of the signal transmitted according to the signal transmission line is set at a unit interval; the impedance discontinuous position is adjusted to obtain a plurality of first adjustment positions, and respectively corresponding The first reflection time is substantially equal to an integer multiple of the unit interval.

In an embodiment of the invention, the step of obtaining the impedance discontinuous position in the signal transmission line according to the first time domain reflection analysis information includes: finding out the first time domain reflection analysis information, and generating a plurality of impedance value surges Corresponding multiple transmission times; and, according to the transmission time, the impedance discontinuities corresponding to the respective transmission times are calculated.

In an embodiment of the invention, the step of setting the operating frequency of the signal according to the signal transmission line by the set unit interval comprises: setting a multiplication inverse element whose unit interval is equal to the operating frequency.

In an embodiment of the present invention, the method for adjusting the layout of the signal transmission line further includes: measuring a step response signal of the signal transmission line, calculating a plurality of second reflection times according to the step response signal; and adjusting the first adjustment position respectively A second adjusted position is obtained such that the second reflection time is substantially equal to an integer multiple of the unit interval.

In an embodiment of the present invention, the step response signal of the measurement signal transmission line, the step of calculating the second reflection time according to the step response signal includes: transmitting the step signal to the signal transmission line, and measuring the signal transmission line according to a step response signal generated by the step signal; and, finding a plurality of transmission times in which the step response signal generates a glitch, and calculating a time distance between adjacent transmission times to generate a second reflection time.

In an embodiment of the invention, the step of respectively adjusting the first adjustment position to obtain the second adjustment position, so that the first reflection time is substantially equal to an integral multiple of the unit interval, further comprises: transmitting the signal transmission line Simulation, and judge the signal transmission quality of the signal transmission line according to the simulation result generated by the signal transmission simulation.

In an embodiment of the invention, the step of adjusting the impedance discontinuous position to obtain the first adjustment position, and causing the respectively corresponding first reflection time to be substantially equal to an integral multiple of the unit interval comprises: measuring the transmission of the signal transmission line Delaying; calculating a plurality of differences of each of the first reflection time and an integral multiple of the unit interval; and adjusting the impedance discontinuous position according to the difference and the transmission delay and obtaining the first adjustment position.

In an embodiment of the invention, the step of adjusting the impedance discontinuous position to obtain the first adjustment position and causing the corresponding first reflection time to be substantially equal to an integral multiple of the unit interval further comprises: re-pairing the signal transmission line The transmitted signal performs time domain reflection analysis and obtains second time domain reflection analysis information; and, checks whether the first reflection time is substantially equal to an integral multiple of the unit interval.

In an embodiment of the invention, the foregoing is generated according to a signal transmission simulation The step of judging the signal transmission quality of the signal transmission line includes: generating an eye diagram according to the signal transmission simulation; and determining the signal transmission quality of the signal transmission line according to whether the effective window of the eye diagram is larger than the preset range.

In an embodiment of the invention, the step of adjusting the impedance discontinuous position comprises: adjusting a position of at least one of the plurality of through holes on the signal transmission line.

In an embodiment of the invention, the step of adjusting the impedance discontinuous position comprises: adjusting a distance between a signal transmission pin of the signal transmission line and an adjacent through hole.

Based on the above, the present invention adjusts the impedance discontinuous position by detecting the discontinuous position of the impedance in the signal transmission line and by an integral multiple of the unit interval. As a result, the reflection phenomenon generated by the transmission signal will not occur in the transmission time enough to affect the signal quality, and effectively reduce the influence of the signal transmission quality caused by the reflection phenomenon.

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

S210~S260‧‧‧Signal transmission line layout adjustment steps

300‧‧‧Transmission wire

SP1, SP2‧‧‧ position

VIA1‧‧‧through hole

410, 610‧‧‧ Curve

TT1, TT2‧‧‧ transmission time

TVIA2‧‧‧Adjusted through hole

TD1, TD2‧‧‧ adjustment distance

RE1‧‧‧ signal transmission pin

TRE1‧‧‧Adjusted signal transmission pin

EH‧‧‧ eye height

1 is an eye diagram of a transmission signal of a signal transmission line of the prior art.

2 is a flow chart showing a method for adjusting a layout of a signal transmission line according to an embodiment of the present invention.

3 is a schematic diagram showing an impedance discontinuity phenomenon of a signal transmission line according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of time domain reflection analysis information according to an embodiment of the invention.

FIG. 5 is a schematic diagram of a method for adjusting an impedance discontinuous position according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of another time domain reflection analysis information according to an embodiment of the present invention.

FIG. 7 is a waveform diagram of a step response signal according to an embodiment of the present invention.

FIG. 8 is an eye diagram of a transmission signal of the adjusted signal transmission line in the embodiment of the present invention.

Please refer to FIG. 2. FIG. 2 is a flowchart of a method for adjusting a layout of a signal transmission line according to an embodiment of the present invention. When performing the layout adjustment operation of the signal transmission line, first, step S210 performs time domain reflection (TDR) analysis on the signal transmission line, and thereby generates time domain reflection analysis information. Wherein, the transmission signal is transmitted in the signal transmission line. When the transmission encounters the position where the impedance occurs in the signal transmission line, the part of the signal in the transmission signal will be reflected, and the other part of the signal will continue to transmit the signal transmission line to continue transmission. . The time domain reflectance analysis calculates the impedance change in the signal transmission line by measuring the voltage amplitude of the reflected wave. At the same time, as long as the time value between the reflection point of the reflected signal and the transmission point of the transmission signal is measured, the position where the impedance discontinuity occurs in the signal transmission line can be calculated.

Here, the position where the impedance is discontinuous refers to a position where the amplitude of the impedance change between the signal transmission lines is larger than a critical value. Among them, the size of the threshold can be set by the designer according to the needs of the signal quality.

For the impedance discontinuity of the signal transmission line, please refer to Figure 3, Figure 3. A schematic diagram of an impedance discontinuity phenomenon of a signal transmission line according to an embodiment of the present invention is shown. In Fig. 3, the transmission wire 300 is bifurcated at the position SP1, and the wire width is reduced at the position SP2. In addition, the transmission line 300 is changed through the through hole VIA1 to be disposed on another layer of the circuit substrate. Among them, the position SP1, the position SP2, and the through hole VIA1 may all be positions where the transmission wire 300 generates an impedance discontinuity.

Please refer to FIG. 2 and FIG. 4 simultaneously. FIG. 4 is a schematic diagram of time domain reflection analysis information according to an embodiment of the present invention. The time domain reflectance analysis information can be plotted as an impedance-time relationship graph. In the example of FIG. 4, curve 410 represents the transmission time and impedance curve produced by time domain reflectance analysis for the signal transmission line. Step S220 obtains a plurality of impedance discontinuous positions in the signal transmission line and a plurality of reflection times corresponding to the adjacent impedance discontinuous positions according to the time domain reflection analysis information. Here, it can be known from the curve 410 that at a time point that is equal to the transmission time TT1 from the origin, a large impedance variation phenomenon occurs in the signal transmission line (that is, an impedance value surge occurs), indicating that the corresponding transmission is in the signal transmission line. An impedance discontinuity occurs at the position of time TT1. In addition, at a time point from the origin approximately equal to the transmission time TT2, another large impedance variation phenomenon may occur in the signal transmission line, indicating that another impedance discontinuity occurs in the signal transmission line at the position corresponding to the transmission time TT2. The transmission time TT1 is equal to the reflection time corresponding to the first impedance discontinuous position of the signal transmission line, and the transmission time TT2 minus the transmission time TT1 may be equal to the reflection time corresponding to the adjacent first and second impedance discontinuous positions of the signal transmission line. .

The above-mentioned impedance value spurt phenomenon can be calculated by analyzing the time domain reflection analysis information and analyzing the change state of the data impedance value, thereby calculating the reflection time corresponding to the impedance value glitch phenomenon.

The impedance discontinuity phenomenon may be determined according to the amplitude of the impedance value surge. When the amplitude of the impedance value surge occurring in the continuous time is greater than a predetermined value, it may be determined that the impedance is generated at the position corresponding to the transmission time on the signal transmission line. Discontinuity. It is worth noting that the above preset values can be set according to the designer's experience and the design requirements of the signal transmission line. There is no fixed limit to the value of the preset value.

On the other hand, in the step of calculating the impedance discontinuous position of the corresponding signal transmission line according to the transmission time, the impedance of the signal transmission line can be obtained according to the transmission delay of the signal transmission line and calculating according to the transmission delay and the above transmission time. Information about discontinuous locations. It is worth noting that the transmission delay of the signal transmission line is related to its type, size and material, and may also be related to the layout of the transmission line on the inner or outer layer of the circuit substrate. Information about the transmission delay can be recorded in the memory, and a processor (or any type of controller) that performs layout adjustment is provided for reading during the layout adjustment of the signal transmission line.

Referring back to FIG. 2, step S230 sets a unit interval according to the operating frequency of the signal transmission line transmission signal. Here, the signal transmitted by the signal transmission line is a periodic signal, and the frequency of the periodic signal is the operating frequency. The unit interval can be set to the multiplication inverse element equal to the operating frequency, that is, the period in which the signal is transmitted. . And in step S240, adjusting the impedance discontinuous position to obtain a plurality of first adjustment bits And the reflection time corresponding to the first adjustment position is substantially equal to an integral multiple of the unit interval.

Please note that the reflection time is calculated based on the transmission signal between the two impedance non-connected points. Therefore, when the impedance discontinuous position is adjusted, the transmission time between adjacent first adjustment positions can be determined. Essentially equal to an integer multiple of half of the unit interval. In this way, the reflected signal affects the time point of the transmitted signal, and substantially falls in the process of the transmission signal transitioning, and does not affect the time interval in which the transmitted signal provides valid data, that is, the reflected signal The impact can be effectively reduced.

For further explanation, please refer to FIG. 5. FIG. 5 is a schematic diagram of a method for adjusting an impedance discontinuous position according to an embodiment of the present invention. When the impedance discontinuous position of the signal transmission line 500 is adjusted, the position of the through hole VIA1 can be adjusted according to the adjustment distance TD2 to obtain the adjusted through hole TVIA2, and the reflected time generated on the adjusted through hole TVIA2 is real. The upper is equal to an integer multiple of the unit interval. Or, for example, adjusting the position of the signal transmission pin RE1 of the signal transmission line 500 to the adjusted signal transmission pin TRE1 according to the adjustment distance TD1, and causing the adjustment signal transmission pin TRE1 and the adjusted through hole TVIA2 to be generated. The reflection time is equal to an integer multiple of the unit interval. The through hole VIA1 and the adjacent through hole (not shown) can be adjusted simultaneously, or only one of them can be adjusted, thereby changing the signal transmission distance between the through hole VIA1 and the adjacent through hole, and the reflection time between them is substantially The upper is equal to an integer multiple of the unit interval. The through hole VIA1 and the signal transmission pin RE1 can also be adjusted synchronously, or only one of them can be adjusted, thereby changing the signal between the through hole VIA1 and the signal transmission pin RE1. The transmission distance is such that the reflection time between them is substantially equal to an integral multiple of the unit interval.

The above-mentioned adjustment distances TD1 and TD2 can be obtained by calculation based on the transmission delay of the signal transmission line. In detail, the difference between the impedance discontinuous positions, the reflection time and the integral multiple of the unit interval can be calculated, and the adjustment distances TD1 and TD2 are calculated according to the difference and the transmission delay to adjust the impedance discontinuity. Position and get the first adjustment position. For example, starting from the signal transmission pin RE1, it is found that impedance discontinuity occurs at the position of the through hole VIA1. Before the adjustment, the difference between the reflection time of the through hole VIA1 and the integral multiple of the unit interval can be calculated. Then, according to the transmission delay of the signal transmission line and the difference described above, the required adjustment is calculated, and the adjustment distances TD1 and TD2 are set to adjust the position of at least one of the through hole VIA1 and the signal transmission pin RE1.

In order to further confirm the effect caused by the adjustment action in step S240, another time domain reflection analysis may be performed on the signal transmission line after step S240, and the new time domain reflection analysis information is obtained. By examining the new time domain reflection analysis information, it can be known whether the reflection time is substantially adjusted to be equal to an integral multiple of the unit interval. Please refer to FIG. 6 for a schematic diagram of another time domain reflection analysis information according to an embodiment of the present invention. Taking the period of the transmitted signal equal to 200 picoseconds (ps) as an example, the impedance-time relationship curve 610 based on the new time domain reflectance analysis information produces two impedance value surges at 189 picoseconds and 962 picoseconds, respectively. . Among them, 189 picoseconds is approximately equal to 200 picoseconds, and the difference between 962 picoseconds and 189 picoseconds (773 picoseconds) is approximately four times that of 200 picoseconds. In actual operation, the reflection time does not have to be adjusted to be exactly equal to an integral multiple of the unit interval, and the reflection time can be adjusted to a single An integer multiple of the bit interval plus or minus a range of error values. Here, the magnitude of the error value can be determined by the designer according to the transmission specification of the signal transmission line, and there is no fixed limit.

By detecting the new time domain reflection analysis information again, it is possible to re-adjust the first adjustment position according to the detection result and optimize the adjustment result.

Referring back to FIG. 2, in order to optimize the layout adjustment of the signal transmission line, the following steps S250 and S260 may be further performed. In step S250, a step response signal of the signal transmission line is measured, and a plurality of reflection times are calculated according to the step response signal. Further, in step S250, the step signal can be transmitted to the signal transmission line, and the step response signal generated by the signal transmission line according to the step signal is measured. Then, a plurality of transmission times of the glitch of the step response signal are found, and the time distance of the adjacent transmission time is calculated to generate the reflection time.

The above-mentioned glitch phenomenon can be calculated by analyzing the step response signal and analyzing the voltage change of the step response signal of the data, thereby calculating the reflection time corresponding to the glitch of the step response signal.

For details of the implementation of step S250, please refer to FIG. 7 in synchronization with FIG. 7, which illustrates a waveform diagram of the step response signal according to the embodiment of the present invention. Among them, it can be found from the curve 710 that the rising edge of the step response signal and the reflection time between the glitch SPK are approximately equal to 803 picoseconds, which is substantially equal to an integral multiple (about 4 times) of the unit interval of 200 picoseconds. Here, if the reflection time between the glitch of the step response signal is not an integral multiple of the unit interval, the reflection time between the glitch of the step response signal and the integer of the unit interval may be used. The difference between the times is used to further adjust the impedance discontinuous position (step S260).

It is worth mentioning that after step S260, the signal transmission line can perform a signal transmission simulation action, and according to the simulation result generated by the signal transmission simulation, whether the signal transmission quality of the signal transmission line can meet the design requirement. Specifically, the eye diagram simulating the transmission signal may be transmitted according to the signal, and the eye pattern of the transmission signal is detected, and whether the effective window has a predetermined range. If the effective window of the eye diagram is larger than the preset range, indicating that the quality of the signal transmission meets the design requirements, the layout adjustment action of the signal transmission line can be ended. If the effective window of the eye diagram is smaller than the preset range, the quality of the signal transmission is indicated. The design requirements cannot be met, and steps S210 to S260 can be re-executed to continue the layout adjustment operation of the signal transmission line.

Finally, please refer to FIG. 8. FIG. 8 is an eye diagram of a transmission signal of the adjusted signal transmission line in the embodiment of the present invention. Wherein, after the reflection time of the reflected signal between the impedance discontinuous positions is substantially adjusted to an integral multiple of the unit interval, it can be found that the eye height EH of the eye diagram in the eye diagram 8 is higher than that of FIG. 1, and the eye window can be maintained at Relatively large range. Indicates that the quality of the transmitted signal is effectively boosted and the effect of the reflected signal is reduced.

It should be noted here that the foregoing various embodiments of the present invention can be implemented by a processor or controller having computing power. The controller can be constructed, for example, by a field-programmable gate array (FPGA) or an application-specific integrated circuit. Among them, control The controller can perform time domain reflection analysis and step response test operation on the signal transmission line through an external or built-in signal generator, and generate data information to provide a basis for the user to perform the position of the through hole of the signal transmission line.

In summary, the present invention adjusts the reflection time of the reflected signal between the discontinuous positions of the impedance by an integral multiple of the unit interval, and reduces the influence of the reflected signal on the transmitted signal, thereby effectively improving the signal quality.

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

Claims (11)

A method for adjusting a layout of a signal transmission line, comprising: performing a time domain reflection analysis on a signal transmitted by a signal transmission line, and obtaining a first time domain reflection analysis information; obtaining the signal transmission line according to the first time domain reflection analysis information a plurality of impedance discontinuous positions, and a plurality of first reflection times respectively corresponding to the adjacent impedance discontinuous positions; setting a unit interval according to an operating frequency of the signal; and adjusting the impedance discontinuous positions to obtain And a plurality of first adjustment positions, and the corresponding first reflection times are substantially equal to an integral multiple of the unit interval. The method for adjusting a layout of a signal transmission line according to the first aspect of the invention, wherein the obtaining the impedance discontinuous positions in the signal transmission line according to the first time domain reflection analysis information comprises: finding the first time domain In the reflection analysis information, a plurality of transmission times corresponding to the plurality of impedance value surges respectively occur; and the impedance discontinuities corresponding to the respective transmission times are calculated according to the transmission times. The method for adjusting a layout of a signal transmission line according to claim 1, wherein the step of setting the unit interval according to the operating frequency of the signal transmission line transmission signal comprises: setting the multiplication inverse element of the unit interval equal to the operating frequency. The method for adjusting a layout of a signal transmission line according to claim 1, further comprising: measuring a step-by-step response signal of the signal transmission line, calculating a plurality of second reflection times according to the step response signal; and separately adjusting the The first adjustment positions obtain a plurality of second adjustment positions such that the second reflection times are substantially equal to an integral multiple of the unit intervals. The method for adjusting a layout of a signal transmission line according to claim 4, wherein the step of measuring the step response signal of the signal transmission line, and calculating the second reflection time according to the step response signal comprises: transmitting one step a step signal to the signal transmission line, and measuring the step response signal generated by the signal transmission line according to the step signal; and finding a plurality of transmission times of the step response signal to generate a glitch, and calculating adjacent ones The time distance between transmission times is used to generate the second reflection times. The method for adjusting a layout of a signal transmission line according to claim 4, wherein the first adjustment positions are respectively adjusted to obtain the second adjustment positions, so that the first reflection times are substantially equal to the unit intervals. After the step of integer multiple, the method further comprises: performing a signal transmission simulation on the signal transmission line, and determining a signal transmission quality of the signal transmission line according to the simulation result generated by the signal transmission simulation. The method for adjusting a layout of a signal transmission line according to claim 6, wherein the step of determining a signal transmission quality of the signal transmission line according to the simulation result generated by the signal transmission simulation comprises: generating an eye diagram according to the signal transmission simulation; Whether the effective window of the eye diagram is greater than a predetermined range determines the signal transmission quality of the signal transmission line. The method for adjusting a layout of a signal transmission line according to claim 1, wherein the impedance discontinuous positions are adjusted to obtain the first adjustment positions, and the corresponding first reflection times are substantially equal to the unit. The step of integer multiple of the interval includes: measuring a transmission delay of the signal transmission line; calculating a plurality of difference values of each of the first reflection time and an integral multiple of the unit interval; and adjusting the difference according to the difference and the transmission delay The impedance is discontinuous and the first adjusted positions are obtained. The method for adjusting a layout of a signal transmission line according to claim 1, wherein the impedance discontinuous positions are adjusted to obtain the first adjustment positions, and the corresponding first reflection times are substantially equal to the unit. After the step of integer multiple of the interval, the method further comprises: performing the time domain reflection analysis on the signal transmitted by the signal transmission line, and obtaining a second time domain reflection analysis information; and checking whether the first reflection times are substantially equal to An integer multiple of this unit interval. The method for adjusting a layout of a signal transmission line according to claim 1, wherein the step of adjusting the impedance discontinuous positions comprises: adjusting a position of at least one of a plurality of through holes on the signal transmission line. The method for adjusting a layout of a signal transmission line according to claim 1, wherein the step of adjusting the impedance discontinuous positions comprises: adjusting a distance between a signal transmission pin of the signal transmission line and an adjacent through hole.