Tunnel transistors are one of the most attractive steep subthreshold slope devices which are being investigating to overcome power density and energy inefficiency exhibited by CMOS technology. These transistors exhibit asymmetric conduction which can cause sustained noise voltage pulses (bootstrapping) within digital TFETs circuits leading to delay degradation. In this paper, we propose a minor modification of the complementary gate topology to avoid the bootstrapping problem and show its impact on speed at the circuit level. Speed improvements up to 33% have been obtained for 8-bit Ripple Carry Adders when implemented with our solution.

Abstract-Tunnel field-effect transistors (TFETs) are one of the most attractive steep subthreshold slope devices currently being investigated as a means of overcoming the power density and energy inefficiency limitations of CMOS technology. In this paper, we analyze the relationship between devices and RT-Level architecture choices. We claim that architectural issues should be considered when evaluating this type of transistors because of the differences in delay versus supply voltage behavior exhibited by TFET logic gates with respect to CMOS gates. More specifically, the potential of pipelining and parallelism, both of which rely on lowering supply voltage, as power reduction techniques is evaluated and compared for CMOS and TFET technologies. The results obtained show significantly larger savings in power and energy per clock cycle for the TFET designs than for their CMOS counterparts, especially at low voltages. Pipelining and parallelism make it possibly to fully exploit the distinguishing characteristics of TFETs, and their relevance as competitive TFET circuit design solutions should be explored in greater depth.

Abstract-This paper presents a design methodology for the simultaneous optimization of jitter and power consumption in ultra-low jitter clock recovery circuits (<100fs rms ) for high-performance ADCs. The key ideas of the design methodology are: a) a smart parameterization of transistor sizes to have smooth dependence of specifications on the design variables, b) based on this parameterization, carrying out a design space sub-sampling which allows capturing the whole circuit performance for reducing computation resources and time during optimization. The proposed methodology, which can easily incorporate process voltage and temperature (PVT) variations, has been used to perform a systematic design space exploration that provides sub-100fs jitter clock recovery circuits in two CMOS commercial processes at different technological nodes (1.8V 0.18µm and 1.2V 90nm). Post-layout simulation results for a case of study with typical jitter of 68fs for a 1.8V 80dB-SNDR 100Msps Pipeline ADC application are also shown as demonstrator.