JPH10293778A - Printed circuit board wiring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a printed circuit wiring board device which detects the effect of crosstalk that occurs when a circuit actually operates before wiring and also reduces crosstalk with circuit wiring in high density. SOLUTION: A sensitive time setting part 14 sets a time zone (sensitive time) that becomes a circuit operational problem because the effect of crosstalk occurs due to the drive of an adjacent net before and after timing when an optional object net is driven according to a logical simulation result 12, and a sensitive net extracting part 15 a net (sensitive net) that drives within the sensitive time. A DRC rule setting part 3 sets a DRC rule (wiring interval rule) which is different from a net where crosstalk is acceptable with an extracted sensitive net as a net where crosstalk is not acceptable. A DRC executing part 5 carries out DRC according to the two kinds of DRC rules.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board wiring apparatus capable of designing wiring on a printed circuit board while considering the influence of crosstalk.

[0002]

2. Description of the Related Art In recent years, as the wiring design of printed circuit boards has become higher in density and higher in speed, when a signal is driven to a net having a circuit, the problem of crosstalk that noise is generated in an adjacent net has become more serious. . FIG. 6 is a block diagram showing a conventional printed circuit board wiring device. In the drawing, reference numeral 1 denotes a board layout unit that creates a board layout information 2 by performing layout design such as arrangement and wiring of a printed board. Reference numeral 3 denotes a DRC rule setting unit for setting physical constraint conditions (hereinafter referred to as DRC rules) such as wiring intervals of a printed circuit board layout, and reference numeral 4 denotes the DRC rule information. Reference numeral 5 denotes a DRC execution unit for checking (hereinafter, simply referred to as DRC) whether or not the board layout information 2 satisfies the DRC rule based on the DRC rule information 4. The error detected by this check is DRC error information 6. And outputs it to the DRC error display unit 7. Reference numeral 8 denotes a transmission line simulation unit for executing a transmission line simulation using the board layout information, and crosstalk information 9 obtained by the simulation.
Are considered in the wiring design in the board layout unit 1.

In such a conventional printed circuit board wiring apparatus, the DRC execution unit 5 converts the board layout information 2 created in the board layout unit 1 into the DRC rule information 4 previously set in the DRC rule setting unit 3. Therefore, DRC is performed. And, as a result, DR
The wiring that does not observe the C rule is output as a DRC error. The transmission line simulation unit 8
The crosstalk information 9 is obtained by performing a transmission line simulation in step (1), and the result is taken into the board layout unit 1. In the board layout unit 1, crosstalk is dealt with by changing the layout such as increasing the wiring interval between nets based on the acquired crosstalk information 9.

[0004]

In the conventional printed circuit board wiring apparatus as described above, the wiring once laid out is changed in consideration of the crosstalk, so that it is necessary to move other wiring and change the route. There is a problem that wiring design cannot be performed at high speed. In addition, when designing based on DRC rules that take into account crosstalk rather than merely physical constraints from the beginning, there is a problem in that wiring intervals are widened even for nets with low crosstalk, and high-density wiring cannot be performed. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A first object of the present invention is to detect the influence of crosstalk generated when a circuit actually operates before wiring. The present invention provides a printed circuit board wiring device that can be used. A second object of the present invention is to provide a printed circuit board wiring device capable of reducing crosstalk while maintaining a high density of board wiring.

[0006]

In a printed circuit board wiring apparatus according to the present invention, means for performing a logic simulation using a netlist and means for setting a sensitive time for an arbitrary target net in the netlist. And means for extracting a sensitive net of the target net from the result of the logic simulation.

In addition, there is provided means for holding two types of wiring interval rules, that is, a wiring interval rule between the extracted sensitive net and the target net, and a wiring interval rule between the net other than the sensitive net and the target net. It is.

[0008] Further, means for setting a maximum allowable crosstalk value between the sensitive net and the target net, and using a transmission line simulation to change the crosstalk value while changing the wiring interval between the sensitive net and the target net. Means for seeking.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a printed circuit board wiring apparatus according to an embodiment of the present invention. In the figure, reference numerals 1 to 7 denote the same or corresponding parts as those of the conventional apparatus shown in FIG. Reference numeral 10 denotes a netlist in which circuit connection information for the logic simulation unit 11 is described, and a logic simulation result 12 is output to a logic simulation result display unit 13. Reference numeral 14 denotes a sensitive time setting unit that sets a time zone (sensitive time) in which the influence of crosstalk occurs due to driving of adjacent nets and causes a problem in circuit operation. Reference numeral 15 denotes a target net selected by the target net selector 16. And a sensitive net extraction unit for extracting all nets (sensitive nets) driven within a sensitive time before and after the drive timing. 17 is the extracted sensitive net information. The DRC rule setting unit 3 sets a rule that is a conventional wiring interval, and inputs sensitive net information 13 that causes a problem in circuit operation when crosstalk occurs, and sets a sensitive net that cannot crosstalk with the target net. A new wiring interval rule is set.

The operation of the printed circuit board wiring apparatus thus configured will be described with reference to the flowchart of FIG. First, a logic simulation is performed based on the netlist 10 (S1), and a logic simulation result 12 is held (S2). Further, the simulation result is displayed on the logic simulation result display section 13 as a waveform (S3). On the other hand, the target net selector 16 selects a target net that requires attention to crosstalk during wiring (S4), and sets a sensitive time of the target net (S5). Next, all the nets other than the target net A driven within the sensitive time before and after all the timings at which the target net is driven are extracted from the logic simulation result 12 (S6). The extracted net is held as a sensitive net (S7), and a DRC rule that defines a spacing rule between wires when the sensitive net is routed adjacent to the target net is set (S8).

For example, as shown in FIG. 3, if a crosstalk occurs due to the driving of an adjacent net before and after the driving timing of the signal A propagating to the net A, which is the target net, there is a problem in circuit operation. The sensitive time is set as follows. In this example, the signal B propagating to the net B is capable of crosstalk, but the signal C propagating to the net C is driven within a sensitive time, so that crosstalk is not possible.
Is extracted. As a result, the same spacing rule 1 as before is set for the net B, and a new spacing rule 2 is set for the net C which is a sensitive net. DRC rules are held for each net (S
9), D for checking whether there is any violation in the board layout
Execute RC (S10). If there is a violation, its DRC
The error information is held (S11) and output to the DRC display unit (S12). As described above, a crosstalk-insensitive net is extracted from the result of the logic simulation, and a spacing rule is set for the net. And the effect of crosstalk is small and high-density printed circuit board wiring design can be performed efficiently.

Embodiment 2 FIG. In the first embodiment, when setting the DRC rule for the sensitive net, the transmission line simulation is performed while changing the wiring interval between the sensitive net and the target net, and the crosstalk value obtained from the result is acceptable. A higher-density wiring can be realized by obtaining a wiring interval that falls within the range of the crosstalk value and setting the minimum value as the DRC rule. FIG. 4 is a block diagram showing detailed functions of the DRC rule setting unit 3 in FIG. In the figure, 2, 4, 8, 9, and 17 are the same or corresponding parts as those of the conventional one shown in FIG. 1
8 is a driver / receiver model used for transmission line simulation, 19 is a virtual wiring width / interval setting unit for virtually setting wiring width and wiring interval when calculating a crosstalk value, and 20 is a parallel portion between wirings. Is an imaginary parallel line length setting unit for setting the length. Reference numeral 21 denotes a transmission line simulator control unit that inputs simulation conditions such as the wiring width / interval and parallel line length to the transmission line simulation unit 8. Reference numeral 22 denotes a spacing rule determining unit that inputs crosstalk information from a transmission line simulation result and determines a wiring interval while comparing the value with a value set by a maximum allowable crosstalk value setting unit 23.

Next, the operation according to the second embodiment will be described with reference to the flowchart of FIG. First, the transmission line simulator control unit 21 reads the sensitive net information 17, the board layout information 2, and a simulation model of a driver for driving a signal to a wiring and a receiver for receiving a signal (T1 to T1).
3). Subsequently, the wiring width / interval and the parallel line length between the wirings are virtually set (T4 to T5). Further, the maximum value of the crosstalk value that is an allowable range is set (T6).
Each simulation condition input to the transmission line simulator control unit 21 is transmitted to the transmission line simulation unit 8, and a transmission line simulation is executed (T7). A crosstalk value is obtained by simulation and held as crosstalk information (T8). Here, if the crosstalk value obtained by the simulation is larger than the maximum allowable crosstalk value set at T6 (NO at T9), the wiring interval virtually set at T4 is set to a small interval. Increase (T1
0), return to T7. If the crosstalk value obtained by re-executing the simulation while increasing the wiring interval falls below the maximum allowable crosstalk value, (T
9 (YES), the wiring spacing set at that time is determined as the minimum spacing (T11), and held as DRC rule information (T12). As described above, higher-density wiring design can be performed while the influence of crosstalk is small.

[0014]

Since the present invention is configured as described above, it has the following effects.

From the result of the logic simulation, a sensitive net in which crosstalk is impossible to be driven within a sensitive time before and after the timing of driving the target net is detected. Therefore, when a circuit is actually driven, a net having an influence of crosstalk is detected. Can be reliably extracted.

Further, for the extracted sensitive net in which crosstalk is not possible, a wiring interval rule different from that of the net in which crosstalk is possible is set, so that wiring with less crosstalk can be efficiently performed.

Further, when setting a wiring interval rule for a sensitive net, a transmission line simulation is performed while changing the wiring interval, and a minimum value when the resulting crosstalk value does not exceed the maximum allowable crosstalk value. Is set as the above-described wiring interval rule, so that higher-density wiring design can be performed with little influence of crosstalk.

[Brief description of the drawings]

FIG. 1 is a functional configuration diagram showing a printed circuit board wiring device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing flow of the printed circuit board wiring apparatus shown in FIG. 1;

FIG. 3 is a diagram illustrating a sensitive net.

FIG. 4 is a configuration diagram showing a detailed function of setting a DRC rule in a printed circuit board wiring device according to a second embodiment of the present invention;

FIG. 5 is a flowchart showing a flow of a DRC rule setting process according to FIG. 4;

FIG. 6 is a functional configuration diagram showing a conventional printed circuit board wiring device.

[Explanation of symbols]

1 board layout section, 3 DRC rule setting section, 4
DRC rule information, 5 DRC execution section, 6 DRC error information, 8 transmission line simulation section, 9 crosstalk information, 10 netlist, 11 logic simulation section, 14 sensitive time setting section, 15 sensitive net extraction section, 16 target net selection Part 1
7 Sensitive net information, 18 Driver / receiver model, 19 Virtual wiring width / spacing setting unit, 20 Virtual parallel line length setting unit, 22 Spacing rule determining unit,
23 Maximum allowable crosstalk value setting section.

Claims (3)

[Claims] A means for performing a logic simulation using connection information of a circuit to be wired (hereinafter referred to as a netlist) in a printed circuit board wiring apparatus for laying out wiring of a printed circuit board based on a predetermined wiring interval rule; A time zone (hereinafter referred to as a sensitive time) in which an influence of crosstalk occurs due to driving of an adjacent net before and after a timing at which the target net is driven with respect to an arbitrary target net in the netlist, and a problem occurs in circuit operation. And a means for extracting, from the result of the logical simulation, all nets (sensitive nets) driven within the sensitive time of the drive timing of the target net, and wiring the extracted sensitive nets Layout based on predetermined wiring spacing rules PCB wiring apparatus according to claim Rukoto. 2. A means for holding two types of wiring interval rules, that is, a wiring interval rule between an extracted sensitive net and a target net, and a wiring interval rule between a net other than the sensitive net and the target net, 2. The printed circuit board wiring device according to claim 1, wherein the wiring of each net is laid out based on a rule of each wiring interval. 3. A means for setting a maximum allowable crosstalk value between a sensitive net and a target net, and using a transmission line simulation to change the crosstalk value while changing the wiring interval between the sensitive net and the target net. 3. A wiring interval rule between the sensitive net and the target net, wherein a minimum wiring interval in which the obtained crosstalk value does not exceed the maximum allowable crosstalk value is provided. Printed circuit board wiring device.