Emerging memories

What is the difference between "bipolar" and "unipolar" operation of ReRAM?

  1. ABipolar uses bipolar transistors and unipolar uses MOSFETs
  2. BBipolar stores 2 bits and unipolar stores 1 bit
  3. CBipolar switches set and reset by reversing the voltage polarity, while unipolar switches with the same polarity by changing the magnitude of voltage or current
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Answer: C. Bipolar switches set and reset by reversing the voltage polarity, while unipolar switches with the same polarity by changing the magnitude of voltage or current

Bipolar ReRAM applies voltages of opposite polarity for set (to low resistance) and reset (to high resistance). Unipolar ReRAM keeps the same polarity and switches by changing the magnitude or duration of the voltage or current. Which mode a device shows depends on its materials and electrode combination.

  • A. The terms do not refer to transistor types.
  • B. It is not a difference in the number of bits stored.
  • C. Correct. The difference is whether voltage polarity is used to switch.
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More Emerging memories questions

  1. In cross-point memories such as PCM, which chalcogenide device, placed in series with the storage element as a selector, suddenly conducts above a certain voltage?
  2. Why must the read current be limited in STT-MRAM?
  3. Which device uses the fact that the tunneling current through a thin ferroelectric layer depends on the direction of its polarization?
  4. Which effect, being studied to reduce MRAM write energy, changes the magnetic anisotropy of a magnetic layer with a voltage?
  5. Which correctly describes how MRAM stores data?