基于RTD和HEMT的单稳多稳转换逻辑(MML)模拟

用 PSpice对一种由串连的 RTD和 HEMT组成的单稳多稳转换逻辑 (MML)电路进行了模拟。基于自行研制的 RTD的特性曲线提取了合适的器件模型和参数 ,分析了由输入信号调节器件的峰值电流来控制器件翻转次序从而在 MML电路中实现门函数逻辑的原理并由模拟得以证实。     

RTD多值逻辑电路原理与电路模拟

由共振隧穿二极管(RTD)和高电子迁移率晶体管(HEMT)构成的多值逻辑(MVL)电路可以用最少的器件来完成一定的逻辑功能,达到大大简化电路的目的。共振隧穿二极管和高电子迁移率晶体管属于量子器件,具有高频高速的特点,所以这一逻辑电路有很好的应用前景。本文就多值逻辑电路中的几个典型电路用Pspice软件进行电路模拟,得到了与理论分析一致的模拟结果。     

共振隧穿器件应用电路概述——共振隧穿器件讲座(2)

在“共振隧穿器件概述”的基础上,对共振隧穿器件应用电路作了全面概括的介绍。首先对共振隧穿器件应用电路的特点、分类和发展趋势作了简述;进一步对由RTDH/EMT构成的单-双稳转换逻辑单元(MOBILE)和以它为基础构成的RTD应用电路,包括柔性逻辑、静态随机存储(SRAM)、神经元、静态分频器等电路的结构、工作原理和逻辑功能等进行了介绍。关于RTD/HEMT构成的更为复杂的电路,如多值逻辑、AD转换器以及RTD光电集成电路等将在本讲座最后部分进行讲解。     

InP基RTD/HEMT集成的几个关键工艺研究

用MBE设备在半绝缘的InP衬底上依次生长高电子迁移率晶体管(HEMT)外延材料和共振遂穿二极管(RTD)外延材料,在此材料结构基础上研究和分析了RTD与HEMT器件单片集成工艺中的隔离工艺、欧姆接触工艺、HEMT栅挖槽工艺和空气桥工艺等几步关键工艺,给出了这些工艺的相关参数。利用上述工艺成功地制作了RTD和HEMT器件,并在室温下分别测试了RTD器件和HEMT器件的电学特性。测试表明:在室温下,RTD器件的峰电流密度与谷电流密度之比(PVCR)为3.66;HEMT器件的最大跨导约为370 mS/mm,在Vds=1.5 V时的饱和电流约为391 mA/mm。这将为RTD与HEMT的单片集成研究奠定工艺基础。     

RTD的器件模型和模拟——共振隧穿器件讲座(9)

阐述了电路模拟在设计和研制大规模集成过程中的必要性和重要意义,器件模型在电路模拟中的重要性以及器件模拟与器件模型的关系;在器件模拟通用软件形成过程的基础上重点讨论了RTD的器件模型、器件模拟和电路模拟软件SPICE三个课题;介绍了基于物理参数I-V方程RTD模型和高斯函数、指数函数RTD直流模型;利用ATLAS器件模拟通用软件对RTD进行了器件模拟,得到了势垒和势阱宽度、E区掺杂浓度等对RTDI-V特性的影响;以包含RTD电路的SPICE电路模拟中的文字逻辑门为例,通过电路模拟验证了其逻辑功能,对设计该电路起到指导和参考作用。     

一种基于RTD和HEMT的单片集成逻辑电路

介绍了一种基于共振隧穿二极管(RTD)和高电子迁移率晶体管(HEMT)的单片集成电路.采用分子束外延技术在GaAs底层上重叠生长了RTD和HEMT结构.RTD室温下的峰谷电流比为5.2∶1,峰值电流密度为22.5kA/cm2.HEMT采用1μm栅长,阈值电压为-1V.设计电路称为单稳态-双稳态转换逻辑单元(MOBILE).实验结果显示了该电路逻辑运行成功,运行频率可达2GHz以上.     

一种基于RTD和HEMT的单片集成逻辑电路

介绍了一种基于共振隧穿二极管(RTD)和高电子迁移率晶体管(HEMT)的单片集成电路.采用分子束外延技术在GaAs底层上重叠生长了RTD和HEMT结构.RTD室温下的峰谷电流比为5.2∶1,峰值电流密度为22.5kA/cm2.HEMT采用1μm栅长,阈值电压为-1V.设计电路称为单稳态-双稳态转换逻辑单元(MOBILE).实验结果显示了该电路逻辑运行成功,运行频率可达2GHz以上.     

光控单稳-双稳转换逻辑单元

用光电晶体管替换HEMT作为输入端,结合RTD可以构成新的光控逻辑单元,它具有光电流开关和自锁功能,该功能在实验及电路模拟中得到证实.在此基础上,若以异质结光电管(HPT)和RTD集成,可以设计和制作诸如D型触发器等不同功能的光控逻辑电路单元.     

光控单稳-双稳转换逻辑单元

用光电晶体管替换HEMT作为输入端,结合RTD可以构成新的光控逻辑单元,它具有光电流开关和自锁功能,该功能在实验及电路模拟中得到证实.在此基础上,若以异质结光电管(HPT)和RTD集成,可以设计和制作诸如D型触发器等不同功能的光控逻辑电路单元.     

光控单稳-双稳转换逻辑单元(英文)

用光电晶体管替换HEMT作为输入端,结合RTD可以构成新的光控逻辑单元,它具有光电流开关和自锁功能,该功能在实验及电路模拟中得到证实.在此基础上,若以异质结光电管(HPT)和RTD集成,可以设计和制作诸如D型触发器等不同功能的光控逻辑电路单元.     

RTD/HPT光控单-双稳转换逻辑单元

以光接收器件代替RTD MOBILE(RTD单-双稳转换逻辑单元)电路中的HEMT或HBT,可构成光控MOBILE电路。在比较了四种光控MOBILE结构的基础上,选择RTD/HPT光控结构,重点分析讨论了RTD/HPT光控MOBILE的工作原理,当光控MOBILE的输入光功率超过一个临界值时,MOBILE的输出电压便会从高电平跳变到低电平;由HPT光增益理论分析了提高HPT性能的措施以及HPT设计中应该注意的问题;介绍了以Si光三极管代替HPT,通过模拟实验,验证了RTD/HPT光控MOBILE的逻辑功能。     

RTD/HEMT串联型RTT的设计与研制

依据RTD/HEMT串联型RTT的概念,设计了RTD/HEMT单片集成材料结构,该结构采用分子束外延技术生长.采用湿法化学腐蚀、金属剥离、台面隔离和空气桥互连技术,研制了RTD/HEMT串联型RTT,并对RTT及RTT中RTD和HEMT的直流特性进行了测试.测试结果表明:在室温下,器件具有明显的栅控负阻特性,正接型RTT的最大峰谷电流之比在2.2左右,反接型RTT的最大峰谷电流之比在4.6左右.实验为RTD/HEMT串联型RTT性能的优化和RTD/HEMT单片集成电路的研制奠定了基础.     

遏止(Quenching)及其在分析RTD逻辑电路中的应用

在深入分析共振隧穿二极管(RTD)开关前后内阻变化和RTD串联组合中不同RTD电压分布随总偏压变化的基础上,深化了“遏止(Q uench ing)”的概念。并进一步以此概念说明了RTD/HEM T电路中,单-双稳转换逻辑单元(M OB ILE)、多值逻辑(M VL)文字(L itera l)逻辑门、三态反相器(T ernary inverter)等逻辑单元的工作原理。通过此种分析,证实了“遏止”概念是解释和分析复杂RTD电路原理的强有力工具。以上论证也适用于由其它负阻器件构成的逻辑电路。     

Ultrahigh-speed HEMT LSI technology for supercomputer

The current status of high electron mobility transistor (HEMT) technology at Fujitsu for high-performance VLSI is presented, focusing on device performance in the submicrometer dimensional range and the HEMT LSIs implemented in supercomputer systems. The HEMT is a very promising device for ultrahigh-speed LSI/VLSI applications because of the high-mobility GaAs/AlGaAs heterojunction structure. A 1.1 K-gate bus-driver logic LSI has been developed to demonstrate the high-speed data transfer in a high-speed parallel processing system at room temperature, operating at 10.92 GFLOPS. A cryogenic 3.3 K-gate random number generator logic LSI with maximum clock frequency of 1.6 GHz has also been developed to demonstrate the high-clock-rate system operations at liquid-nitrogen temperature. For VLSI level complexity, a HEMT 64-kb static RAM with 1.2-ns access operation and a 45 K-gate gate array with 35-ps logic delay have been developed operating at room temperature, demonstrating the high performance required for future high-speed computer systems     

Mixed-mode simulation of DX trap-induced slow transient effects onAlGaAs/GaAs HEMT inverters

A mixed level device and circuit simulation was performed to analyze DX trap-induced slow transient effects on the performance degradation of AlGaAs/GaAs high electron mobility transistor (HEMT) circuits. The variation of the output pulsewidth and the hysteretic characteristics of the input-output voltage transfer function in direct-coupled FET logic (DCFL) HEMT inverters have been simulated. In the model, a DX trap rate equation is calculated in the AlGaAs layer. The self-consistent Schrodinger and Poisson equations are solved numerically at each cross section of a device. A two-region Grebene-Ghandhi model is used to derive the I-V characteristics. The simulation confirms that the output pulse broadening and narrowing effects in string cascaded DCFL HEMT inverters are a consequence of the inverter voltage transfer function shift caused by deep traps     

A GaN/InGaN/AlGaN MQW RTD for versatile MVL applications with improved logic stability

To improve the logic stability of conventional multi-valued logic (MVL) circuits designed with a GaN-based resonate tunneling diode (RTD),we proposed a GaN/InGaN/AlGaN multi-quantum well (MQW) RTD.The proposed RTD was simulated through solving the coupled Schrodinger and Poisson equations in the numerical non-equilibrium Green's function (NEGF) method on the TCAD platform.The proposed RTD was grown layer by layer in epitaxial technologies.Simulated results indicate that its current-voltage characteristic appears to have a wider total negative differential resistance region than those of conventional ones and an obvious hysteresis loop at room temperature.To increase the Al composite of AlGaN barrier layers properly results in increasing of both the total negative differential resistance region width and the hysteresis loop width,which is helpful to improve the logic stability of MVL circuits.Moreover,the complement resonate tunneling transistor pair consisted of the proposed RTDs or the proposed RTD and enhanced mode HEMT controlled RTD is capable of generating versatile MVL modes at different supply voltages less than 3.3 V,which is very attractive for implementing more complex MVL function digital integrated circuits and systems with less devices,super high speed linear or nonlinear ADC and voltage sensors with a built-in super high speed ADC function.