This work presents a non-volatile content-addressable memory (NV-CAM) based on double-barrier magnetic tunnel junction technology (DMTJ). Unlike state-of-the-art NV-CAM designs that present low-performance updates, our NV-CAM allows energy-efficient, high-performance search and update operations. This makes it well-suited for applications requiring a high frequency of searches/updates, such as associative processors. The NV-CAM hybrid CMOS/DMTJ was designed using a commercial 65nm CMOS technology and a Verilog-A-based DMTJ compact model. The NV-CAM evaluation was carried out by employing Monte Carlo simulations while accounting for process variations. Simulation results show that our NV-CAM presents competitive figures of merit compared to state-of-the-art design. Our NV-CAM presents energy-efficient operations and reduces the update and search delay by about 71% and 75%, respectively, compared to other NV-CAMs.

Content-addressable memory (CAM) is a specialized memory architecture designed for fast data searches, allowing a one-clock-cycle comparison between the search input and the entire memory content. In this work, a low matchline voltage swing CAM is proposed to reduce the search power consumption while maintaining high-speed search operations. Low voltage swing in the matchline is enabled by introducing extra circuitry in the conventional CAM cell. By means of comprehensive Monte Carlo and post-layout simulations using a commercial 65nm node, we show that the proposed CAM cell design allows for robustness against process, voltage, and temperature variations without the need for dedicated matchline sense schemes. Compared to conventional precharge high NOR-type CAM, the proposed design achieves 42% higher speed and 29.1% less energy consumption. Post-layout results demonstrate that the proposed CAM operates reliably at 0.6V, maintaining performant and reliable search operations across a wide temperature range.

Low-Power high-performance content-addressable memories (CAMs) are important components in modern computing systems. In this work, we present a robust CAM that overcomes the power and performance limitations of conventional precharge-based CAMs. The proposed static transmission gate-based (STAT-TG) CAM design achieves low-power operation comparable to NAND CAMs while maintaining search speeds rivaling those of NOR CAMs. The STAT-TG CAM was designed using a 65nm CMOS technology and comprehensively evaluated under extensive Monte Carlo simulations. Compared to conventional CAMs, the STAT-TG CAM is 14% faster than NAND CAM, while consuming only 25% of the energy per operation relative to NOR CAM. This makes STAT-TG CAM a promising solution for high-performance yet energy-efficient applications.

Content-addressable memory (CAM) is a specialized type of memory that facilitates massively parallel comparison of a search pattern against its entire content. State-of-the-art (SOTA) CAM solutions are either fast but power-hungry (NOR CAM) or slow while consuming less power (nand CAM). These limitations stem from the dynamic precharge operation, leading to excessive power consumption in NOR CAMs and charge-sharing issues in NAND CAMs. In this work, we propose a precharge-free CAM (PCAM) class for energy-efficient applications. By avoiding precharge operation, PCAM consumes less energy than a NAND CAM, while achieving search speed comparable to a NOR CAM. PCAM was designed using a 65-nm CMOS technology and comprehensively evaluated under extensive Monte Carlo (MC) simulations while taking into account layout parasitics. When benchmarked against conventional NAND CAM, PCAM demonstrates improved search run time (reduced by more than 30%) and 15% less search energy. Moreover, PCAM can cut energy consumption by more than 75% when compared to conventional NOR CAM. We further extend our analysis to the application level, functionally evaluating the CAM designs as a fully associative cache using a CPU simulator running various benchmark workloads. This analysis confirms that PCAMs represent an optimal energy-performance design choice for associative memories and their broad spectrum of applications.

The Dual Mode Logic (DML) defines run-time adaptive digital architectures that switch to either improved performance or lower energy consumption as a function of actual computational workload. This flexibility is demonstrated for the first time by silicon measurements on a 16×16-bit Booth multiplier fabricated as a part of an ultra-low power digital signal processing (DSP) architecture for 16-nm FinFET technology. When running in the full-speed mode, the DML multiplier can achieve a performance boost of 19.5% as compared to the equivalent standard CMOS design. The same design saves precious energy (-27%, on average) when the energy-efficient mode is enabled, while occupying 13% less silicon area.

This demo demonstrates the unique capabilities of the multimode Dual Mode Logic (DML) design technique to define run-time adaptive datapaths to overcome process and environmental (i.e., temperature and voltage) variations. A proof-of concept benchmark circuit is designed and fabricated in 65 nm technology. Measurements on 10 test chips, while considering supply voltages spanning 0.6V to 1.2V and temperature variations ranging from - 40 ° C to 125 ° C confirmed the effectiveness of the proposed approach to compensate even for severe process, voltage and temperature (PVT) variations.

In the past, Pass Transistor Logic (PTL) was widely used due to benefits in terms of speed and power consumption coming from the reduced number of transistors. However, issues such as threshold drop across the single-channel pass transistors and high sensitivity to process variations have prevented the use of PTL in advanced nanometer technologies. In this paper, we propose a novel logic family named Dual Mode Pass Logic (DMPL), which allows for high speed and low power consumption while maintaining robustness down to the sub-threshold voltage region. The DMPL effectively combines PTL to reduce energy and power consumption along with the flexibility of Dual Mode Logic (DML) to switch to a speed improved operating mode according to the system requirement. Simulation analysis performed on basic NOR/NAND gates implemented in 16 nm Finfet technology demonstrates that DMPL can reduce energy and power by 33% and 42% as compared to logically equivalent static CMOS design. Moreover, running frequency of a DMPL circuit can exceed that of its static CMOS counterpart by 84% when speed is mandatory. Additionally, DMPL gates demonstrate similar robustness as static CMOS implementations under process and temperature variations at lower supply voltages.

In this paper we evaluate the implementation options of energy-efficient dual mode logic (DML) circuits in 28nm fully depleted silicon-on-insulator (FD-SOI) technology. The combination of the flexibility of Dual Mode Logic (DML) and the unique characteristics of the FD-SOI technology has enormous potential to design energy-efficient adaptive digital circuits operating on an ultra-wide voltage range. As a main result, we demonstrate that single well option offered by the FD-SOI greatly extends the low-granularity energy-delay (E-D) optimization capability of DML-based designs. By exploiting the above implementation strategy, a 16-bit DML carry skip adder reduces its energy consumption by 41% and increases its speed of about 26% when changing its operation mode (from static to dynamic) at 0.4V as compared to its equivalent standard CMOS design.

Address decoders are integral components of random access memories. In higher-performance computing, the timing of address decoders is often critical, especially in applications such as translation lookaside buffer (TLB) and first level data cache. On the other hand, memory power budget and energy consumption are equally critically important for battery-powered devices. Dual Mode Logic (DML) has been shown to combine the support for both requirements in a single circuit. We present a novel DML based address decoder design and compare it with conventional static CMOS and np-CMOS address decoders. Simulations show that DML based address decoder in dynamic mode achieves 31% lower delay compared to conventional static CMOS implementation. In static mode, DML based address decoder reduces the energy consumption by 29% and reaches 10% lower energy-delay product compared to static CMOS address decoder. This is the first time DML is evaluated in 16nm FinFet process.

The unique ability of dual mode logic (DML) to self-adapt to computational needs by providing high speed and/or low energy consumption is demonstrated for the first time by silicon measurements in 28nm FD-SOI. At the gate level, the DML design offers the possibility to operate either in the static mode to save energy, or in the dynamic mode to increase speed albeit with higher delay or energy consumption, respectively. In this demonstration, the two operational modes are dynamically managed by a self-adjustment mechanism to increase speed or reduce energy of the design at run-time. As a test case a two-stage pipelined multiply-accumulate (MAC) circuit was selected to assess the advantages of DML in terms of speed, energy and area as compared to a conventional CMOS design. We show that the self-adjusted DML MAC achieves both a performance boost of up to 92% and 16% less energy consumption than the equivalent standard CMOS implementation. The energy saved can be even greater (-35%) when the low-power (fully static) mode is enabled. In addition, the DML MAC occupies 25% less area.

For the first time, the Dual Mode Logic (DML) technique is evaluated in 28 nm UTBB FD-SOI technology, with the goal of improving energy efficiency for wide supply voltage operation range. By combining the operating characteristics of the DML and the extended body bias capability of the technology, energy efficient digital circuits that can effectively benefit from adaptive voltage and frequency scaling techniques can be defined. This manuscript reports evaluations of the DML against conventional static and dynamic CMOS logics for two benchmarks in the 0.3V-1V supply voltage range. First, a NAND-NOR chain was considered. Simulation results showed that the DML approach assures roughly the 40% savings in terms of energy consumption with respect to the static CMOS implementation and improves the speed about 20% in comparison to the dynamic CMOS design. Second, a 16-bit Carry Skip Adder was considered. Due to the unique capability of the DML to switch on-the-fly between static and dynamic modes of operation, an improvement of more than 20% in terms of EDP was obtained in comparison to the conventional CMOS adder design.

Recently, we proposed a low-granularity back-bias control technique [1] optimized for the ultra-thin body and box (UTBB) fully-depleted silicon-on-insulator (FD-SOI) technology. The technique was preliminary evaluated through the design of a low-voltage 8-bit ripple carry adder (RCA), showing very competitive energy and delay values. In this paper, the characteristics of the low-granularity back-biasing control are explored considering as benchmarks basic logic gates as well as adders with different bit lengths. All the designed circuits were compared to their equivalent dynamic threshold voltage MOSFET (DTMOS) and conventional CMOS designs. The higher efficiency of low granularity body bias control is emphasized by the single well layout strategy, offered by the 28 nm UTBB FD-SOI technology, thus leading our approach to achieve competitive silicon area occupancy along with significant performance and energy improvements. More precisely, post-layout simulations have demonstrated that circuits designed according the suggested strategy, can achieve a delay reduction of 33% compared to conventional CMOS designs, whereas the energy consumption can be reduced down to 46% compared to DTMOS solutions, for a supply voltage of 0.4V. These results were obtained while maintaining robustness against process and temperature variations.