Signal Margin TEST for 4-D, 4-D With Poly Load or 6-D Random Access Memories
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Memory array margins may be determined during the test phase through the utilization of a capacitive voltage divider which is programmed by an external voltage source. The CMOS circuitry utilized for signal margin testing is shown in Fig. 1. During standby, Data line (DL) and Data Line "not" (DL "not") are precharged (PC) high to VDD by Bit Line PC "not" (BLPC "not") and the Clock (CLK) is low so that the voltage levels on PAD "X" and PAD "Y" are transferred into nodes A and B. Then, when CLK is high, nodes A and B are isolated from DL and DL "not". To test for signal margins, CLK "not" will go low and CLK will go high after BLPC "not" goes high and before the Data Line goes high. Depending on the levels in nodes A and B, DL and DL "not" will drop by a value WV < (VDD - V) C/(C + CDL "not").