Ambipolar dual-gate transistors based on low-dimensional materials, such as graphene, carbon nanotubes, black phosphorus, and certain transition metal dichalcogenides (TMDs), enable reconfigurable logic circuits with a suppressed off-state current. These circuits achieve the same logical output as complementary metal–oxide semiconductor (CMOS) with fewer transistors and offer greater flexibility in design. The primary challenge lies in the cascadability and power consumption of these logic gates with static CMOS-like connections. In this article, high-performance ambipolar dual-gate transistors based on tungsten diselenide (WSe2) are fabricated. A high on–off ratio of 108 and 106, a low off-state current of 100 to 300 fA, a negligible hysteresis, and an ideal subthreshold swing of 62 and 63 mV/dec are measured in the p- and n-type transport, respectively. We demonstrate cascadable and cascaded logic gates using ambipolar TMD transistors with minimal static power consumption, including inverters, XOR, NAND, NOR, and buffers made by cascaded inverters. A thorough study of both the control gate and the polarity gate behavior is conducted. The noise margin of the logic gates is measured and analyzed. The large noise margin enables the implementation of VT-drop circuits, a type of logic with reduced transistor number and simplified circuit design. Finally, the speed performance of the VT-drop and other circuits built by dual-gate devices is qualitatively analyzed. This work makes advancements in the field of ambipolar dual-gate TMD transistors, showing their potential for low-power, high-speed, and more flexible logic circuits.
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EMC: Efficient Muller C-Element Implementation for High Bit-width Asynchronous Applications
A Muller C-Element is a digital circuit component used in most asynchronous circuits and systems. In Null Convention Logic, the Muller C-Elements make up the subset of THmn threshold gates where the threshold, m, and the input bit- width, n, are equal. This paper presents a new Efficient Muller C- Element implementation, EMC, that is especially suitable for Null Convention Logic applications with high input bit-widths, and it is much faster and smaller than standard implementations. It has a two-transistor switching delay that is independent of the input bit- width, n, and exhibits low noise and static power consumption. It is suitable for all Muller C-Element applications, especially those like Null Convention Logic register feedback circuits that can have large input bit-widths. To reduce static power consumption, it uses active resistors that are only turned “ON” when necessary. Two output stages are presented to implement the required Muller C- Element digital hysteresis: standard, semi-static cross-coupled inverter version, and differential sense-amplifier option. For large values of n, our circuit requires approximately one-half fewer transistors than combining smaller Null Convention Logic THmn semi-static threshold gates. We have successfully simulated up to n = 1024 at a 65 nm node.
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- Award ID(s):
- 1916722
- NSF-PAR ID:
- 10280574
- Date Published:
- Journal Name:
- 64th IEEE International Midwest Symposium on Circuits and Systems
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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