13 research outputs found
Designing with Iontronic Logic Gates -- From a Single Polyelectrolyte Diode to Small Scale Integration
This article presents the implementation of on-chip iontronic circuits via
small-scale integration of multiple ionic logic gates made of bi-polar
polyelectrolyte diodes. These ionic circuits are analogous to solid-state
electronic circuits, with ions as the charge carriers instead of
electrons/holes. We experimentally characterize the responses of a single
fluidic diode made of a junction of oppositely charged polyelectrolytes (i.e.,
anion and cation exchange membranes), with a similar underlying mechanism as a
solid-state p- and n-type junction. This served to carry out pre-designed
logical computations in various architectures by integrating multiple
diode-based logic gates, where the electrical signal between the integrated
gates was transmitted entirely through ions. The findings shed light on the
limitations affecting the number of logic gates that can be integrated, the
degradation of the electrical signal, their transient response, and the design
rules that can improve the performance of iontronic circuits
Silicon-Proven, Per-Cell Retention Time Distribution Model for Gain-Cell Based eDRAMs
Gain-cell embedded DRAM (GC-eDRAM) is an interesting alternative to SRAMfor reasons such as high density, low bitcell leakage, logic compatibility, and suitability for 2-port memories. Themajor drawbacks of GC-eDRAMs are their limited data retention times (RTs) and the large spread of RT across an array, which degrade energy-efficiency due to refresh cycles. While the array refresh rate can be determined according to circuit simulation or post-manufacturing calibration, there is a lack of analytical and statistical RT models for GC-eDRAM that could unveil the limiters and circuit parameters that lead to the large observed RT spreads. In this work, we derive the first comprehensive analytical model for the statistical distribution of the per-cell retention time of 2T-bitcell GC-eDRAMs, which is found to follow a log-normal distribution. The accuracy of the proposed retention time model is verified by extensive Monte Carlo and worst case distance circuit simulations and silicon measurements of an 0.18 mu m test chip. Furthermore, a sensitivity analysis unveils the circuit parameters that have the highest impact on the RT spread. Interestingly, the variability of the threshold voltage of the write access transistor has a much higher impact on the RT spread than the variability of any other circuit parameter, including the storage node capacitor. This holds true under process scaling, for nodes as advanced as 28 nm, as shown through simulation. The insights gained from the retention time model help circuit designers achieve better GC-eDRAMs with longer RTs and sharper RT distributions. In addition, the herein presented model can be used as a basis to study the reliability/energy trade-off for GC-eDRAM usage in fault-tolerant VLSI systems
Designing with Iontronic Logic GatesFrom a Single Polyelectrolyte Diode to an Integrated Ionic Circuit
This article presents the implementation of on-chip iontronic
circuits
via small-scale integration of multiple ionic logic gates made of
bipolar polyelectrolyte diodes. These ionic circuits are analogous
to solid-state electronic circuits, with ions as the charge carriers
instead of electrons/holes. We experimentally characterize the responses
of a single fluidic diode made of a junction of oppositely charged
polyelectrolytes (i.e., anion and cation exchange membranes), with
a similar underlying mechanism as a solid-state p- and n-type junction.
This served to carry out predesigned logical computations in various
architectures by integrating multiple diode-based logic gates, where
the electrical signal between the integrated gates was transmitted
entirely through ions. The findings shed light on the limitations
affecting the number of logic gates that can be integrated, the degradation
of the electrical signal, their transient response, and the design
rules that can improve the performance of iontronic circuits