Patent ID: 8804445
Filing Date: 2014-08-12
Classification: G11C,H03K

Abstract:
1. A ring oscillator based on a 6T SRAM for measuring a Bias Temperature Instability, the ring oscillator having at least 4 SRAM cells, wherein the SRAM cell being formed by 6-transistor structure, every SRAM cell having a first inverter including a first pull-up transistor and a first pull-down transistor, a second inverter including a second pull-up transistor and a second pull-down transistor, a first pass-gate transistor, a second pass-gate transistor, a first pass-gate transistor and a second pass-gate transistor, the first pass-gate transistor being coupled with the first inverter, and the second pass-gate transistor being coupled with the second inverter, the ring oscillator comprising: a first inverter; a first control unit, which being electrically connected with the first inverter, the first control unit being used to control the first inverter being selected, biased, and connected respectively; a second inverter, which being electrically connected with the first inverter; and a second control unit, which being electrically connected between the first control unit and the first inverter, the second control unit being used to control the second inverter being selected, biased, and connected respectively; the first control unit and the second control unit being used to measure the Negative Bias Temperature Instability and a Positive Bias Temperature Instability of the SRAM cell, and monitoring a real-time reliability of the SRAM cell.