Patent ID: 7330392

Claim:
A dual port semiconductor memory device comprising: a memory cell array including a plurality of memory cells, each cell including: a first CMOS inverter including a first NMOS transistor, a first PMOS transistor, an input port, and an output port; a second CMOS inverter including a second NMOS transistor, a second PMOS transistor, an input port coupled to the output port of the first CMOS inverter and constitutes a first memory node together with the output port of the first CMOS inverter, and an output port coupled to the input port of the first CMOS inverter and constitutes a second memory node together with the input port of the first CMOS inverter; a third NMOS transistor having a gate coupled to a wordline, a drain coupled to a bitline, and a source coupled to the first memory node; a fourth NMOS transistor having a gate coupled to the wordline, a drain coupled to a complementary bitline, and a source coupled to the second memory node; and a third PMOS transistor having a gate coupled to a scan address line, a source coupled to the second memory node, and a drain coupled to a scan data-out line; where the memory cell is divided into first and second n-wells where P+ active regions are formed and first and second p-wells where N+ active regions are formed; where the first p-well, the second p-well, the first n-well, and the second n-well are arranged on the semiconductor substrate in an alternating manner; a plurality of wordlines and a plurality of scan address lines; a plurality of pairs of bitlines, comprised of bitlines and complementary bitlines, and a plurality of scan data-out lines; a read/write row decoder unit to select one from among the plurality of wordlines; a scan row decoder unit to select one from among the plurality of scan address lines; a column decoder unit to select one from among the plurality of pairs of bitlines; a scan latch circuit unit to latch data output to the plurality of scan data-out lines and to thus generate scan output signals; a precharge circuit unit to precharge the plurality of pairs of bitlines; a predischarge circuit unit to predischarge the plurality of scan data-out lines; a data input/output gate unit to input and output data to the plurality of pairs of bitlines; a sense amplifier unit to amplify a voltage difference between each of the plurality of bitlines; and a data input/output circuit unit to generate output data using data output from the sense amplifier unit and to output data to the data input/output gate unit.