Recent breakthroughs in associative memories suggest that silicon memories are coming closer to human memories, especially for memristive Content Addressable Memories (CAMs) which are capable to read and write in analog values. However, the Program-Verify algorithm, the state-of-the-art memristor programming algorithm, requires frequent switching between verifying and programming memristor conductance, which brings many defects such as high dynamic power and long programming time. Here, we propose an analog feedback-controlled memristor programming circuit that makes use of a novel look-up table-based (LUT-based) programming algorithm. With the proposed algorithm, the programming and the verification of a memristor can be performed in a single-direction sequential process. Besides, we also integrated a single proposed programming circuit with eight analog CAM (aCAM) cells to build an aCAM array. We present SPICE simulations on TSMC 28nm process. The theoretical analysis shows that 1. A memristor conductance within an aCAM cell can be converted to an output boundary voltage in aCAM searching operations and 2. An output boundary voltage in aCAM searching operations can be converted to a programming data line voltage in aCAM programming operations. The simulation results of the proposed programming circuit prove the theoretical analysis and thus verify the feasibility to program memristors without frequently switching between verifying and programming the conductance. Besides, the simulation results of the proposed aCAM array show that the proposed programming circuit can be integrated into a large array architecture.

翻译：联想记忆的最新突破表明，硅基存储器正逐渐接近人类记忆，尤其是能够读写模拟值的忆阻式内容可寻址存储器（CAM）。然而，作为目前最先进的忆阻器编程算法，程序验证算法需要在验证和编程忆阻器电导之间频繁切换，这带来了高动态功耗和长编程时间等诸多缺陷。在此，我们提出一种模拟反馈控制忆阻器编程电路，该电路采用一种新颖的基于查找表（LUT）的编程算法。利用所提出的算法，忆阻器的编程和验证可以在单向顺序过程中完成。此外，我们还将单个提出的编程电路与八个模拟CAM（aCAM）单元集成，构建了一个aCAM阵列。我们基于台积电28纳米工艺进行了SPICE仿真。理论分析表明：1. aCAM单元内的忆阻器电导可在aCAM搜索操作中转换为输出边界电压；2. aCAM搜索操作中的输出边界电压可在aCAM编程操作中转换为编程数据线电压。所提出的编程电路的仿真结果验证了理论分析，从而证明了无需在验证和编程电导之间频繁切换即可编程忆阻器的可行性。此外，所提出的aCAM阵列的仿真结果表明，该编程电路可集成到大规模阵列架构中。