I was wondering if I could get some information from those who have experience in SRAM cell design and sense amplifiers. I don't have much experience in this. For fun, I'm trying to build a small SRAM-based register file that will have two read ports and one write port. The goal is to read on the positive edge of the clock and write a data on the negative edge of the clock.
My goal is to try to fabricate this as a test chip on MOSIS AMI 0.5 um using 5V. Naturally, I'm using Electric ;) My SRAM cell supporting 2 reads, 1 write is as shown here: http://imagebin.ca/view/1Iwk5z4.html Although, I should probably run in through SPICE simulation and see if checks out, I'm fairly sure its OK. I was able to get IRSIM to pass this. bitA, bitB are precharged to logic high before the word lines are asserted. If the cell contains a 0, the bitlines will begin to discharge. The write is done through bitC where both data and data_b are required on the access transistors. The problem is the sense amplifier. I'm been reading a few books including Dr. Baker's. However, the sense amplifiers there operate on bit and bitb (bit bar lines). In my schematic, I have a single line for reading. Consequently, an initial try of my sense amplifier is as follows: http://imagebin.ca/view/4zGSFZQ.html The main issue is VDD connection on the left side of the schematic which ties the output of the inverter to 1. I'm not sure if the left inverter is even necessary here? Because if bit is 1, sense_bit should be 1. However, if the line is beginning to discharge (i.e. bit is going from VDD -> 0), sense_bit should be 0. Is there a better way to design the sense amplifier that works only only a single line? Can Dr. Baker comment on this? The phis is the sense clock which when activated isolates the sense amplifier from the rest of the SRAM cells through the PMOS isolation transistor on the right. Thanks for any insights anybody might have. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Electric VLSI Editor" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/electricvlsi?hl=en -~----------~----~----~----~------~----~------~--~---
