How many different ways can you actually specify WHERE group repeaters land on a route, and how do they differ?
From PDVerse PnR Interview Handbook, part of the pdVerse Mentor Guide
Short Answer
place_group_repeaters offers several mutually exclusive location-specification methods: -repeater_distance (distance between groups, with -first_distance and -min_distance_repeater_to_load defaulting to half the repeater distance), -relative_distance (driver-to-first, first-to-second, etc.), -location (exact center of each group), -number_of_repeater_groups (total count inserted evenly along the route), and -cutlines (location pairs defining cutlines perpendicular to the route, with groups centered around them). Each represents a genuinely different way of thinking about placement -- distance-based, count-based, or geometry-based.
Technical Explanation
- -repeater_distance specifies the distance between repeater groups; -first_distance sets driver-to-first-group distance separately; -min_distance_repeater_to_load defaults to HALF of -repeater_distance unless overridden; -tolerance defaults to 5 microns.
- -relative_distance instead specifies distances one hop at a time: driver-to-first, first-to-second, and so on -- a sequence of relative gaps rather than one uniform distance.
- -location specifies the exact center coordinate of each group directly -- no distance math at all, just stated positions.
- -number_of_repeater_groups specifies a total COUNT to insert evenly along the route -- the tool figures out the spacing to achieve that count.
- -cutlines defines location pairs as cutlines perpendicular to the routes, with repeater groups centered around them -- a geometry-first way of specifying placement rather than a distance- or count-first one.
- These are mutually exclusive -- you pick ONE way of thinking about where repeaters go, not a combination of several.
Common Mistake
The Trap: Trying to combine two of these location-specification methods (e.g. both -repeater_distance and -cutlines) on the same call -- they're mutually exclusive, representing different ways of specifying the same underlying placement decision.
Follow-up Question & Model Response
"When would -cutlines specifically be the right choice over the distance-based or count-based methods?"
Candidate Model Response: When the placement constraint is genuinely geometric -- for example, needing repeaters to land at a specific physical boundary (a voltage area edge, a macro channel) rather than at a specific distance interval or a specific total count -- -cutlines lets you specify that boundary directly rather than trying to back-calculate a distance or count that happens to land there.
Practical Example
Practical Example: place_group_repeaters -cells <list> -number_of_repeater_groups 4 inserts exactly 4 repeater groups evenly spaced along the route, while place_group_repeaters -cells <list> -cutlines {{{500 100} {500 800}}} instead places one group centered on a specific vertical cutline at x=500 -- two genuinely different ways of answering "where do the repeaters go."
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