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Physical / electrical concepts

Impedance coupon / TDR report

Time Domain Reflectometry
Test strip on the panel that the fab measures to prove the controlled-impedance traces hit target (e.g. 90 ohm USB, 100 ohm MIPI).

How it looks

Drawing: no coupon was ordered for CORE3588; its fab notes say "no controlled-impedance testing or coupon requested for this fast prototype order"
A PRODUCTION PANELboardboardcoupon: a test strip with tracks built exactly like ours
The coupon rides on the panel edge, is measured, then thrown away.

How it works

MEASURING THE COUPONmeasured impedancealong the striptarget: 100 ohm (camera pairs)the stripsend a fast step inflat at the target = pass; a bump = wrong width or thickness

Where it fits

The coupon proves the stackup hit its impedance target. CORE3588 targets 90 ohm USB and 100 ohm camera pairs as design goals only.

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