Current Switch Read/Write Port Circuit for Multi-Port Array Cells
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
A single read/write port replaces one read port and one write port, by use of the described current switch read/write port circuit (CSRWPC), with a resultant saving in silicon and metal chip areas, i.e., a more dense chip, by the elimination of two bit lines, one word line and one resistor per read/write port. An array cell using a single CSRWPC is shown in Fig. 4. It functions in the following manner: When the word line 1 is down, and both bit lines 2 and 3 are down, the cell is being read and there is current in the resistor 4. The current is steered out of the right bit line through the right outboard transistor T4 if the array cell contains a '0'. The current is steered out of the left bit line through the left outboard transistor T1 if the cell contains a '1'.