Subthreshold conduction

About: Subthreshold conduction is a research topic. Over the lifetime, 6343 publications have been published within this topic receiving 131957 citations. The topic is also known as: Subthreshold leakage.

Robust subthreshold logic for ultra-low power operation

Abstract: Digital subthreshold logic circuits can be used for applications in the ultra-low power end of the design spectrum, where performance is of secondary importance. In this paper, we propose two different subthreshold logic families: 1) variable threshold voltage subthreshold CMOS (VT-Sub-CMOS) and 2) subthreshold dynamic threshold voltage MOS (Sub-DTMOS) logic. Both logic families have comparable power consumption as regular subthreshold CMOS logic (which is up to six orders of magnitude lower than that of normal strong inversion circuit) with superior robustness and tolerance to process and temperature variations than that of regular subthreshold CMOS logic.

Subthreshold conditions as precursors for full syndrome disorders: a 15-year longitudinal study of multiple diagnostic classes.

Abstract: Since the advent of well-specified psychiatric diagnostic systems, such as the DSM’s 1980 3rd revision, reliability of diagnoses has greatly improved as has the precision of prevalence rates. These systems employ specific thresholds for determining ‘caseness’ but, recently, interest in studying subthreshold conditions (i.e., slightly below the threshold) has increased (Pincus, McQueen, & Elinson, 2003). This work is especially important because subthreshold conditions are common (Lewinsohn, Shankman, Gau & Klein, 2004), and are associated with functional impairment (Kessler, Zhao, Blazer, & Swartz, 1997) Studying subthreshold conditions can help determine whether full syndromes (FS) are qualitatively different from conditions below diagnostic thresholds or whether they are merely more severe forms on a continuum (Flett, Vredenburg, & Krames, 1997; Lewinsohn, Solomon, Steeley, & Zeiss, 2000a). Among subthreshold conditions, subthreshold depression has been studied the most extensively. Subthreshold depressive conditions, such as minor depression or Brief Recurrent Depression, have been associated with significant impairment (Gotlib, Lewinsohn, & Seeley, 1995; Kessler et al., 1997), and increased treatment utilization (Judd, Paulus, Wells & Rapaport, 1996). Similar results have been found for subthreshold bipolar (Lewinsohn, Klein & Seeley, 2000b), anxiety (Batelaan, De Graaf, Van Balkom, Vollebergh, & Beekman, 2007), and alcohol and substance use disorders (Pollock & Martin, 1999). The clinical significance and validity of subthreshold conditions can be addressed with several different methods (Robins & Guze, 1970). Cross-sectional studies can establish the prevalence of subthreshold conditions and whether they are associated with impairment. Family studies can elucidate whether FS and subthreshold conditions are associated with qualitatively distinct familial liabilities. Using data from the Oregon Adolescent Depression Project (OADP), we have begun to examine these questions (Lewinsohn et al., 2004; Shankman, Klein, Lewinsohn, Seeley & Small, 2008). In this paper, we will extend these studies by examining the prospective course of subthreshold conditions. Specifically, we will examine whether subthreshold conditions are likely to develop or escalate into FS disorders. Subthreshold depression (Fergusson, Horwood, Ridder & Beautrais, 2005; Lewinsohn et al., 2000a) bipolar disorder (Lewinsohn et al, 2000b; Regeer et al., 2006) and anxiety disorder (Merikangas et al., 2003) have been shown to escalate into the FS condition over time. These and similar studies have led many to argue that subthreshold conditions may be precursors of the FS (Eaton, Badawi & Melton, 1995, Pincus et al., 2003). Most subthreshold studies only examine whether a single subthreshold condition is likely to develop into the FS form of that disorder over time (i.e., homotypic development). Equally important, however, is whether subthreshold conditions predict the development of other FS disorders over time (i.e., heterotypic development), as heterotypic developments can elucidate whether subthreshold conditions are precursors to broad classes of psychopathologies. With the possible exception of MDD and bipolar disorder, heterotypic developments have been largely ignored in the subthreshold literature (Lewinsohn et al., 2000b; Regeer et al., 2006). We predict that, in addition to homotypic escalation, several subthreshold conditions will develop into heterotypic FS disorders, as there is substantial comorbidity and familial co-aggregation among subthreshold and FS conditions (Angst, Merikangas & Preisig, 1997; Lewinsohn et al., 2004; Shankman et al., 2008). Given the phenotypic and genotypic clustering of psychopathologies into broad classes of internalizing and externalizing disorders (Kendler, Prescott, Myers, & Neale, 2003; Krueger & Markon, 2006), we expect that subthreshold internalizing disorders such as depression and anxiety will escalate into FS forms of each other (Fergusson et al., 2005), and subthreshold externalizing disorders such as alcohol, substance, and conduct /antisocial personality disorder (ASPD) will escalate into FS forms of one another (Hicks et al., 2007). It is also possible that externalizing subthreshold conditions may escalate into internalizing conditions given recent support (Kim-Cohen et al., 2003), though these findings are less likely than within class escalation.

A 180mV FFT processor using subthreshold circuit techniques

Abstract: Minimizing energy requires scaling supply voltages below device thresholds. Logic and memory design techniques allowing subthreshold operation are developed and demonstrated. The fabricated 1024-point FFT processor operates down to 180mV using a standard 0.18/spl mu/m CMOS logic process while using 155nJ/FFT at the optimal operating point.

Vertical tunnel field-effect transistor

Abstract: The realization of a novel vertically grown tunnel field-effect transistor (FET) with several interesting properties is presented. The operation of the device is shown by means of both experimental results as well as two-dimensional computer simulations. This device consists of a MBE-grown, vertical p-i-n structure. A vertical gate controls the band-to-band tunneling width, and hence the tunneling current. Both n-channel and p-channel current behavior is observed. A perfect saturation in drain current-voltage (I/sub D/--V/sub DS/) characteristics in the reverse-biased condition for n-channel, an exponential and nearly temperature independent drain current-gate voltage (I/sub D/--V/sub GS/) relation for both subthreshold, as well as on-region, and source-drain off-currents several orders of magnitude lower then the conventional MOSFET are achieved. In the forward-biased condition, the device shows normal p-i-n diode characteristics.

Robust subthreshold logic for ultra-low power operation

Abstract: Digital subthreshold logic circuits can be used for applications in the ultra-low power end of the design spectrum, where performance is of secondary importance. In this paper, we propose two different subthreshold logic families: 1) variable threshold voltage subthreshold CMOS (VT-Sub-CMOS) and 2) subthreshold dynamic threshold voltage MOS (Sub-DTMOS) logic. Both logic families have comparable power consumption as regular subthreshold CMOS logic (which is up to six orders of magnitude lower than that of normal strong inversion circuit) with superior robustness and tolerance to process and temperature variations than that of regular subthreshold CMOS logic.