C-PHY

This item checks Length Matching and Separation rule between Nets of C-PHY Interface.

Unlike other interfaces, the C-PHY Interface is composed of three lines, and these three lines must be designed to meet the specifications of length matching and separation.
  • Item: Input item name.
  • Net: Select C-PHY pair net group.
  • Trio Pair Filter: Enter a filter to choose trio pair net from selected net group.
  • Shield Net: Set GND Net Group to operate as Shield.
  • Component Keep IN/OUT: Define test region. For example, you can test inside or outside the breakout region of CPU with different test values.
    • Component Group: Select required component group which is used for defining the test region.
    • Region: Define the required test region.
      • IN: DFE tests the inside of the breakout region of target component.
      • OUT: DFE tests the outside of the breakout region of target component.
    • Range (COC+distance): Enter the distance value to define breakout range. The COC (Component Overlap Check) plus this distance value is considered the test range.
    • Target Layer: Select the required test layer.
      • All Layer: Test all layers.
      • Component Place Layer: Test only component placement layer.
    • Include Pin/Via: DFE checks the net separation including Pin/VIA.
  • Type: Define separation measure base.
    • Value: The clearance value is considered as Separation Value.
    • Width: The value is considered as multiple of Pattern Width.
  • Intra-Pair Spacing (Min): Allowable minimum spacing between net.
  • Inter-Pair Spacing (Min): Allowable minimum spacing between pair.
  • Intra-Pair Skew(Max): Allowable maximum length skew between net.
  • Inter-Pair Skew(Max): Allowable maximum length skew between pair.
    Figure 1.


  • H-Shield Check: Option for horizontal shield check.

H-Shield Check

Horizontal Shield Check
  • Shield Distance: Distances from nets in net group from ground nets in GND net group.
    • Use Width Value(W): The value in Shield Distance is considered as multiple of Pattern Width.
    • Max: Specify maximum distance from differential pair net to ground. The DFE searches shielding net within this range.
    • Min: Specify minimum clearance from net to ground. If shield net exists closer than this clearance, it reports as failed.
  • Min Horizontal Shield Ratio(%): Minimum shielding net length ratio against total net. If the shielding ratio is smaller than the given value, it is reported as failed.

    Ratio = The total length of shielded portion of net/Total length of net

  • Shield Ratio Calculation Type: Determine shield ratio calculation method.
    • All Layer: Calculate shield ratio for total net.
    • Per Layer: Calculate shield ratio for per each layer.
    • Inner Layer: Calculate shield ratio for internal layer only.
    • Pin Escape: Enter a radius of circular region around pins to be excluded for the rule check.
    • Via Escape: Enter a radius of circular region around vias to be excluded for the rule check.
    • Exclude Short Pattern: Exclude the short length trace shorter than this value.
    • Include trace corner: The ground shield length at which signal bend is always longer than signal trace length. This leads to results that are not accurate. In order to eliminate this problem, the DFE ignores the bending position. The DFE includes the bending position when calculating shield ratio.
    • Include Inner VIA Shielding: In the case of Inner Layer VIA where the net is not connected, check the shielding.
Guard Via Distance Check: The DFE checks maximum via distance of shielding net.
  • Guard Via Range: Define the maximum distance from trace edge within which guard via should be exist. The DFE considers only the vias within this range as a guard via.
  • Max Via Distance: If the via distance is greater than this value, it is reported as failed.
  • Except PAD: Exclude pin pad for testing.
  • Merge Result Via Count: PollEx DFE shows the merged result of all errors on the same display.
  • V-Shield Check: Option for vertical shield check.
    • Shield Distance(Extended V-Shield Width): Specify the minimum required GND width of upper/below layer.
    • Min Vertical Shield Ratio(%): Minimum ground shielding ratio. If the shielding ratio is smaller than the given value, it is reported as failed.

      Ratio = Shield Area/Net Area

    • Shield Ratio Calculation Type: Determine test layer.
      • All Layer: Calculate shield ratio for total net.
      • Per Layer: Calculate shield ratio per each layer.
      • Inner Layer: Calculate shield ratio for internal layer only.
    • Exclude/Include Option

      Check Layer

      • L1 Layer: check one layer above and below.
      • L2 Layer: check two layers above and below.
      • L2-Hop Layer: check two layers one layer apart above and below.
      • Pin Escape: Enter a radius of circular region around pins to be excluded for the rule check.
      • Via Escape: Enter a radius of circular region around vias to be excluded for the rule check.
      • Exclude Short Pattern: Exclude the short length trace shorter than this value.
      • Consider both upper and lower direction: The above and below layer will be tested if not wider layer side will be checked(above or below)

Report

In the report display, the target net’s shielded sections are shown in cyan color, other regions are violet color. Target net length, shielding length and input ratio appear in the report display.