发明授权
US08964470B2 Method and architecture for improving defect detectability, coupling area, and flexibility of NVSRAM cells and arrays 有权
用于改善NVSRAM单元和阵列的缺陷可检测性,耦合面积和灵活性的方法和架构

Method and architecture for improving defect detectability, coupling area, and flexibility of NVSRAM cells and arrays
摘要:
Several preferred embodiments of 1S1F 16T NVSRAM, 1S1F 20T NVSRAM, 1S2F 22T NVSRAM, 1S2F 14T NVSRAM cells are proposed, regardless of 1-poly, 2-poly, PMOS or NOS flash cell structures. Two separate sourcelines for the paired flash Strings are also proposed for easy adding ability for the NVSRAM circuit to detect the marginally erased Vt0 and marginally programmed Vt1 of the paired flash cell. By increasing an resistance added to common SRAM power line, the pull-down current through flash Strings to grounding source line can be made much larger than the pull-up current to improve SFwrite program operation. Simple method by increasing flash cell channel length to effectively enhance coupling area is applied to secure SRAM-to-Flash store operation under self-boost-program-inhibit scheme. 1S2F architecture also provide flexibility for alternate erasing and programming during both a recall and store operation.
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