Memristor can do multistate processing as well as nonvolatile memory
by noreply@blogger.com (brian wang) from NextBigFuture.com on (#29BT3)
Short of full blown molecular computers or universal quantum computers or optical computers memristors have the most potential for a hardware change to dramatically boost the power and capabilities of computers. The boost to computer power could be nearly a million times by fully leveraging memristors. It would likely be more like a thousand times with more near to mid term usage of memristors.
Memristors (aka ReRAM) could become computer memory that is over 10 times denser than Flash or DRAM in two dimensions. Memristors like flash would be nonvolatile memory that would not need power for retain memory. Memristors are created from nanowire lattices which could be stacked in three dimensions. Memristors have also previously been shown to behave like brain synapses which could be used for computer architectures that emulate the human brain for neuromorphic computing. Now there is work on multistate memristors that perform computation. This means that eventually processing and memory could be tightly integrated.
Light travels 30 centimeters in 1 nanosecond. Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length. Logic gates can have propagation delays ranging from more than 10 ns down to the picosecond range, depending on the technology being used.
Memristors by allowing multiple state processing to live side by side with memory would vastly reduce latency and delays within computers. Memristors can also have more than binary (two) states.
However, as Hewlett Packard has discovered it is very difficult to redesign computers and software to leverage the new capabilities of memristors. This is being done and could see systems that get close to realizing the close to the full potential of memristors in the 2020s.
Redox-based resistive switching random access memories (ReRAMs) are considered as one of the most promising emerging non-volatile memory technologies. The devices can be scaled down to 5"nanometers offer endurance up to 10^12 cycles, 10 years retention and fast read / write speed of below 200"ps. The devices are switched to a low resistive state (LRS) for a positive SET voltage and switched to the high resistive state for a negative RESET voltage. Up to 8 multi-states have been show, allowing the storage of up to three binary digits in a single cell. Additionally ReRAM devices offer highly non-linear switching kinetics, i.e. the SET time depends exponentially on the pulse amplitude. Due to abrupt switching events the common approach is to apply an external current compliance (CC) to enable multi-level resistance states. The drawback of this approach is that the final resistance is defined by the CC, but not by the actual applied pulse amplitudes. However, a direct correlation between pulse height and final resistive state is feasible for a gradual RESET process, where a Vstop voltage defines the resistive state in advanced valence change mechanism (VCM) devices. In this work, we use optimized Pt / W / TaOx / Pt ReRAM devices, offering highly reliable stop-voltage behavior and use the corresponding multi-level properties to implement modular arithmetic operations, as discussed in the result section.
Developed Modular Arithmetic Working Principle
The new developed algorithm calculates the carries and sums directly in the ReRAM devices, which store the results until they are read out. Initially, all the devices in a wordline are initialized, i.e. written to the LRS. Starting from this state the sum bit of significance 0 (s0) can be directly calculated in the device of significance 0 while the other devices are calculating the first output carry c1. The actual sum or carry calculating devices are shifted for each significance one device to the left.
In general, for the carry algorithm,
first the device state of the actual device is read, to check whether the input carry is 0 or 1.
Next, the logic operation is conducted after a SET operation using the evaluated OFFSET
Finally, the resistive state of the device is read and evaluated.
To enable a proper modulus operation the ReRAM device has to provide 2n states for an n-ary number system
State machine
Resistive switching device structures
Nature - Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic
Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced.
Read more
Memristors (aka ReRAM) could become computer memory that is over 10 times denser than Flash or DRAM in two dimensions. Memristors like flash would be nonvolatile memory that would not need power for retain memory. Memristors are created from nanowire lattices which could be stacked in three dimensions. Memristors have also previously been shown to behave like brain synapses which could be used for computer architectures that emulate the human brain for neuromorphic computing. Now there is work on multistate memristors that perform computation. This means that eventually processing and memory could be tightly integrated.
Light travels 30 centimeters in 1 nanosecond. Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length. Logic gates can have propagation delays ranging from more than 10 ns down to the picosecond range, depending on the technology being used.
Memristors by allowing multiple state processing to live side by side with memory would vastly reduce latency and delays within computers. Memristors can also have more than binary (two) states.
However, as Hewlett Packard has discovered it is very difficult to redesign computers and software to leverage the new capabilities of memristors. This is being done and could see systems that get close to realizing the close to the full potential of memristors in the 2020s.
Redox-based resistive switching random access memories (ReRAMs) are considered as one of the most promising emerging non-volatile memory technologies. The devices can be scaled down to 5"nanometers offer endurance up to 10^12 cycles, 10 years retention and fast read / write speed of below 200"ps. The devices are switched to a low resistive state (LRS) for a positive SET voltage and switched to the high resistive state for a negative RESET voltage. Up to 8 multi-states have been show, allowing the storage of up to three binary digits in a single cell. Additionally ReRAM devices offer highly non-linear switching kinetics, i.e. the SET time depends exponentially on the pulse amplitude. Due to abrupt switching events the common approach is to apply an external current compliance (CC) to enable multi-level resistance states. The drawback of this approach is that the final resistance is defined by the CC, but not by the actual applied pulse amplitudes. However, a direct correlation between pulse height and final resistive state is feasible for a gradual RESET process, where a Vstop voltage defines the resistive state in advanced valence change mechanism (VCM) devices. In this work, we use optimized Pt / W / TaOx / Pt ReRAM devices, offering highly reliable stop-voltage behavior and use the corresponding multi-level properties to implement modular arithmetic operations, as discussed in the result section.
Developed Modular Arithmetic Working Principle
The new developed algorithm calculates the carries and sums directly in the ReRAM devices, which store the results until they are read out. Initially, all the devices in a wordline are initialized, i.e. written to the LRS. Starting from this state the sum bit of significance 0 (s0) can be directly calculated in the device of significance 0 while the other devices are calculating the first output carry c1. The actual sum or carry calculating devices are shifted for each significance one device to the left.
In general, for the carry algorithm,
first the device state of the actual device is read, to check whether the input carry is 0 or 1.
Next, the logic operation is conducted after a SET operation using the evaluated OFFSET
Finally, the resistive state of the device is read and evaluated.
To enable a proper modulus operation the ReRAM device has to provide 2n states for an n-ary number system
State machine
Resistive switching device structuresNature - Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic
Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced.
Read more