Implementation of a One-Transistor Multiple-Valued Content-Addressalbe Memory and Its Application

存储模块和逻辑模块之间的通信瓶颈是多媒体VLSI系统中最严重的问题之一。其中逻辑电路元件分布在存储单元阵列上的存储器中逻辑结构是解决上述问题的关键技术。内容可寻址存储器(CAM)是典型的存储器中逻辑超大规模集成电路的一种。然而，由于存储和逻辑元素的开销，CAM的构建更加复杂，存储密度也低于RAM等常规存储器，因此提出了一种基于浮栅MOS传输管逻辑的高性能多值CAM，用于在有限的芯片面积内执行高度并行的幅度比较。所提出的多值存储数据对应于浮栅MOS晶体管的阈值电压，因此可以仅使用单个MOS晶体管来设计CAM单元电路。此外，还提出了一种基于这种多值浮栅MOS传递晶体管网络的存储器中逻辑VLSI结构，以实现具有多值输入和二进制输出的并行算术和逻辑电路。本项目的主要成果如下：(1)凸轮高度并行的幅度比较硬件算法；(2)基于浮栅MOS的多值通道晶体管网络的存储器中逻辑VLSI结构；(3)基于铁电器件的功能通道门及其应用；(4)电流/电压混合模式多值集成电路。

Communication bottleneck between memory and logic modules is one of the most serious problems in the multimedia VLSI systems on a chip. A logic-in-memory structure, in which logic-circuit elements are distributed over a memory-cell array, is a key technology to solve the above problem. A content-addressable memory (CAM) is one of the typical logic-in-memory VLSIs. However, CAMs have been more complex to build and had lower storage density than a normal memory such as RAMs because of the overhead involved in the storage and logic elements.In this project, a high-performance multiple-valued CAM based on floating-gate-MOS pass-transistor logic is proposed to perform highly parallel magnitude comparisons in a limited chip area. Multiple-valued stored data in the proposed CAM correspond to the threshold voltage of a floating-gate MOS transistor, so that the CAM cell circuit can be designed by using only a single MOS transistor. Moreover, a logic-in-memory VLSI architecture based on such a multiple-valued floating-gate-MOS pass-transistor network is also proposed to realize parallel arithmetic and logic circuits with multiple-valued inputs and binary outputs. The main results of this project are listed below :(1) Highly Parallel Magnitude-Comparison Hardware Algorithm for CAMs,(2) Logic-in-Memory VLSI Architecture Using Floating-Gate MOS-Based Multiple-Valued Pass-Transistor Network,(3) Functional Pass Gate Based on Ferroelectric Devices and Their Application,(4) Current/Voltage-Hybrid-Mode Multiple-Valued Integrated Circuits.