Feedthrough Wire Analysis

Technology improvements--related to tracking the drivers and loads on a net more accurately, thus enabling more accurate low-power semantics for a net--have been enabled in feedthrough wire analysis for AMS Designs. The following are the consequences of the improved behavior:

• ISO devices are not created for a floating net, that is, a net without driver and load.

• If logical expressions are embedded in a continuous assignment statement, both the driver and receiver of that assignment statement are corrupted when that block is in the power shut-off mode. This is different from the behavior in 11.1, where only the receiver was corrupted. Example:
  module dig_child (lin);
inout lin;
...
assign ltmp = ~lin;
endmodule

The continuous assignment statement assign ltmp = ~lin; contains a bitwise negation operator, based on which the nets ltmp and lin do not qualify as feedthrough wires. The nets are forced to X state when the dig_child block is in the power shut-off mode.

For more information about feedthrough analysis, refer to the Feedthrough Wires section in the Low-Power Simulation Guide.