Honored Contributor
Honored ContributorOkay well I'm not going to claim to be an authority on this. At one time I worked for a very large DRAM manufacturer. I designed Flash, DDR, and DDR2 memory test equipment.
First you need to ask yourself what it is you are trying to analyze. 1 - Are you designing your own memory controller and need to analyze gross timing of your control / data signals? A logic analyzer is appropriate and useful in this case and I wouldn't hesitate suggesting that you buy the interposer. 2 - Are you just anticipating problems in your PCB layout and want to be able to analyze them when the memory doesn't work? A logic analyzer is not as useful here. It may help tell you if you've got an open or short somewhere. It might reveal if you've made some dramatic mistake (like making one DQ trace in a group far too long or short compared to the others). But if you are trying to view the signal integrity of the signals, this is not going to help. . If you measure the signals anywhere except at the destination pins (FPGA or memory pins depending on who's driving), the signal is not going to look good. I'm sure you understand why this is the case. If you need to do some signal integrity checking, it's best to probe the module at the via that connects to the ball in question. We would often take a DIMM or SODIMM and rip some of the parts off it so we could probe at the best places. Or we would solder little test pins to the module so we could connect an oscope or logic analyzer to them. Again, just my opinion. Maybe somebody else will have something better. Jake
