Self-test method for testing read stability in a dual-port sram cell

Abstract

A structure and method for testing multi-port SRAM cells includes a test controller connected to at least one multi-port SRAM cell (the test controller is adapted to store a pattern into the multi-port SRAM cell and generate a stability test restore clamp), a read/write controller connected to the multi-port SRAM cell (the read/write controller is adapted to simultaneously activate a plurality of wordline ports on the multi-port SRAM cell while the stability test restore clamp is enabled), and a timing control circuit connected to the read/write controller. The timing control circuit is adapted to vary an activation time of the wordline ports. The read/write controller reads from the multi-port SRAM after the stability test restore clamp is deactivated. The read/write controller activates the wordline ports for each multi-port SRAM cell in an array sequentially while all bitlines in the array are held on by the stability test restore clamp. The structure also includes a logic device connected to the test controller adapted to prevent the stability test restore clamp from being enabled unless a test is being performed. The timing control circuit is adapted to be selectively externally controllable to vary the activation time of the wordline ports. The timing control circuit can include a plurality of delay units adapted to be selectively engaged to vary the activation time of the wordline ports. The stability test restore clamp is enabled for at least a wordline pulse.