A trombone is a length-tuning detour in which a trace runs out and folds back on itself, like the slide of the instrument, so a signal arrives with the others in its group, as in a DDR byte lane or the two legs of a differential pair. Designers use the word loosely for any serpentine meander, while layout tools separate trombone, accordion and sawtooth tuning patterns. Loop spacing must stay generous, typically at least three to four trace widths, or adjacent segments couple and the delay added is less than the length suggests.
DQ5 is 80 mils short, put a trombone in it near the controller and keep the loops at least 4W apart.
Also heard as
- serpentine
- meander
Related terms
Differential pair
Two traces carrying equal and opposite signals, routed tightly together at matched length and impedance.
Impedance control
Designing and building traces to a target impedance, such as 50 or 100 ohms, within a set tolerance.
Trace
Copper conductor path etched on a board layer, connecting pads, vias and planes.