Impact of dynamic variability on the operation of CMOS inverter

Abstract

The impact of dynamic variability due to low-frequency fluctuations on the operation of CMOS inverters, which constitute the basic component of SRAM cell, is investigated. The experimental methodology to characterise the effect of dynamic variability in a CMOS inverter is first established based on fast I-V measurements of the load current following the application of a ramp input voltage Vin(t). It is shown that, for small ramp rise times, the load current characteristics IDD(Vin) exhibit a huge sweep-to-sweep dispersion due to low-frequency noise. The impact of such dynamic variability sources on the inverter's output characteristics V out(Vin) is finally demonstrated, revealing a 20% noise margin reduction for the smallest inverter cell. © The Institution of Engineering and Technology 2013.