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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of

Graphene and Molybdenite Join Forces for a New Flash Memory

Now researchers at École polytechnique fédérale de Lausanne (EPFL) in Switzerland have combined graphene, which has already been shown to be effective as a basis for flash memory, with molybdenum disulfide (MoS2 or molybdenite), which is developing into graphene’s biggest two-dimensional material rival, into a flash memory prototype with improved performance.

The research, which was published in the journal ACS Nano (“Nonvolatile Memory Cells Based on MoS2/Graphene Heterostructures”), builds on the work EPFL had done in using molybdenite to create a working transistor. Since the development of a working transistor, the EPFL team has continued to focus its attention on the two-dimensional material to explore its potential applications.

To demonstrate the versatility of molybdenite, the Swiss researchers have combined it with graphene to create a flash memory prototype that is at least theoretically capable of being faster and with greater power efficiency than conventional silicon designs.

"Combining these two materials enabled us to make great progress in miniaturization, and also using these transistors we can make flexible nanoelectronic devices," says Andras Kis, author of the study, in a press release.



The flash memory prototype was built around field-effect geometry that forms the basis of field-effect transistors (FETs) used in complementary metal-oxide semiconductor (CMOS) electronics. In this case, the Swiss researchers replaced the silicon that would make up the middle layer of the sandwich-like device with the molybdenite. Graphene electrodes reside beneath this layer of molybdenite to transmit electricity into the molybdenite. The top layer of the device is several layers of graphene, which capture electrical charge and thereby stores memory.

The researchers believe this architecture should make for a more efficient flash memory design. The graphene is a much better at conducting electricity than silicon and the molybdenite is more sensitive to charge because it is far thinner than silicon.