Why is there a tRRD in DDR3? There does not seem to be a resource conflict between different banks

Question

In DDR3, bank activation is specific to the Bank, for different banks, they all have their own sense amp and do not seem to affect each other, so why would there be tRRD?

Answer 1

As you said, different banks have their own sense amplifiers and row decoders, but they do also share the same row and bank address decoding and driving paths. However, tRRD is not limited by logic and data conflicts as many other timing parameters are.

tRRD and tFAW are there to limit accumulation of activation noise. If activations to different banks are too close each other then the tail ends of the activation current waveforms are added up to a significant amount.