Practical approach to programmable analog circuits with memristors (0908.3162v2)

Abstract: We suggest an approach to use memristors (resistors with memory) in programmable analog circuits. Our idea consists in a circuit design in which low voltages are applied to memristors during their operation as analog circuit elements and high voltages are used to program the memristor's states. This way, as it was demonstrated in recent experiments, the state of memristors does not essentially change during analog mode operation. As an example of our approach, we have built several programmable analog circuits demonstrating memristor-based programming of threshold, gain and frequency.

• The paper demonstrates a two-voltage scheme that programs memristor states to control threshold, gain, and frequency in analog circuits.
• It introduces a practical memristor emulator built with accessible components to validate the proposed circuit designs through empirical testing.
• The findings highlight memristors’ potential to expand analog circuit functionality by offering simple, scalable, and programmable electronic solutions.

Practical Approach to Programmable Analog Circuits with Memristors

The paper "Practical approach to programmable analog circuits with memristors" by Yuriy V. Pershin and Massimiliano Di Ventra presents a methodological framework for implementing memristors as programmable elements in analog circuits. The authors propose an innovative circuit design strategy where memristors function under low voltage for analog operations and are programmed at higher voltages.

Core Contributions

The primary contribution is the demonstration of memristor-based circuits capable of programming threshold, gain, and frequency. Memristors—resistors with memory—are utilized in these circuits as programmable components. The authors highlight the potential to exploit memristor properties for analog memory applications, expanding beyond the traditional binary mode usage.

Design Approach

The paper outlines a two-fold voltage scheme: low operational voltages ensure stability in the analog circuit, while high voltages are used for programming the memristor state. This approach leverages the memristor's threshold-type behavior, whereby changes in memristance are significant only above certain voltage levels.

Memristor Emulator

Given the practical unavailability of commercial memristors, the authors construct a memristor emulator. This device mimics memristive behavior using accessible electronic components, providing a platform to validate their circuit designs. The emulator's operational limits (such as frequency and resistance range) are dictated by the selected components, offering both programmability and scalability.

Applications Demonstrated

The authors showcase several circuit applications demonstrating the versatility of memristors in analog settings:

1. Programmable Threshold Comparator: By adjusting the memristor's resistance, the comparator threshold is dynamically programmable, showcasing voltage-driven adaptability.
2. Programmable Gain Amplifier: The circuit's gain is modified by shifting the memristance value, allowing fine control over amplification levels through a simple design methodology.
3. Programmable Switching Thresholds Schmitt Trigger: The memristor adjusts switching thresholds, proving useful in controlling signal hysteresis.
4. Programmable Frequency Relaxation Oscillator: Frequency modulation is achieved via memristor-driven threshold adjustments, highlighting applications in signal processing.

Numerical Insights

The authors provide empirical data from their experiments with the emulator, validating memristor-based designs through observable I-V characteristics and circuit response experiments. The changes in circuit behavior align with theoretical predictions, reinforcing the practicality of their approach.

Implications and Future Directions

The paper proposes a paradigm shift towards utilizing memristors in analog contexts, broadening their application scope in electronics. Potentially, memristors could enhance components like digital potentiometers, given their non-volatility and simplicity.

From a theoretical standpoint, the work invites further exploration into diverse memristive materials and models to refine precision and applicability. The presented strategy exemplifies how emerging memory-circuit elements like memelements, can be harnessed for innovative electronic solutions.

Conclusion

This paper systematically outlines an actionable blueprint for integrating memristors into programmable analog circuits, with a robust demonstration via emulation. It presents a compelling case for memristors in expanding the functionality and efficiency of analog electronics, positioning them as pivotal components in future technological advancements.