When routing diff pairs manually, the field solver activates and runs calculations. the constraint manager modes are turned off and the DRC check is disabled. It still takes 1-2 miutes or more to start a route and every move of the mouse causes more calculations. Any way of turning off the field solver to speed up routing manually.
Thank you. A fellow designer and I set this up and it works great. You are correct in that the mfg numbers for impedance are better than the Cadence numbers. I usually get close with Allegro, but not confident with it.
Actually it's all about your process... we interact very tightly with our PCB vendor and as such have a limited set of suppliers. When we take their data (we specifiy weave type on every layer for many reasons...) we can usually be within 1/2 ohm of their target impedance.If we weren't to interact, then your generalization is true. I don't allow my designs to be handled in such a manner so I can in fact rely on the Cadence solver to accurately predict what the impedance is going to be. :)