Bit Cell Ratio Testing

1. Bit Cell Ratio Testing

2. Thin Cell Advantages: Smallest possible area of 6T Bit Cell, Can be mirrored (saves area = can reduce distance between n-wells and p-wells)

3. 2by2 Array of Thin Cell Layout Advantages: WLs are horizontal, VDD/VSS/BL/BLB are vertical, Mirrored Thin Cells save area and make it easy to add N/P Taps, Easy to Cascade to other 2by2 Arrays

4. Buffers (First Inv = Min Size, Second Inv = 4x Min) Advantages: Needs to be thin to have 2 Buffers to be smaller than the width of a Thin cell, Easy to souce VDD and VSS, Easily connect inputs and outputs (top and bottom of diagram), Easily N-Tapped, P-Tapped

5. Word Select (1to2 DEMUX) – Sends Data to Column Advantages: Data comes from top, Address from side (design decision), N-wells together, P-wells together (easy to add N-taps and P-taps), easily mirrored

6. TX Gates (4x Min Size) – Disconnects BL Drivers, Avoids Fight between Bitcells and BL Drivers Advantages: Outputs nicely spread apart, Select lines are all tied together and come in from side, Inputs from top, Outputs on bottom, Easily N-Tapped and P-Tapped from left or right side, Easily mirrored.

7. Precharge/BL/BLB Generator Advantages: Pitched Matched (Made it as thin as possible while fitting it in with rest of circuit), BL/BLB are on the outsides running vertically, Easily P-Tapped, N-Tapped, Thin, PRECH, WRITE, and Data Signals

8. Sense Amp Advantages: Wanted as short as possible, but width had to be smaller than width of Thin Cell, Similar to Thin Cell by using Cross Coupled Inverter layout, Easily mirrored, Easily P-Tapped, N-Taped

9. 1 SRAM Block Advantages: Symmetrical, Pitched Match (All separate components fit in nicely), 1 VDD/VSS source for Bit Cell Array, Can be mirrored, Most inputs, Inputs come in from Left and Top side

10. Block Pair Merger Schematic

11. Block Pair Merger

12. Block Pair

13. Decoder

14. Layout Diagram(Connections Removed to Reduce Clutter)