Compact multiple-valued multiplexers using negative differential resistance devices

Abstract

Quantum electronic devices with negative differential resistance (NDR) characteristics have been used to design compact multiplexers. These multiplexers may be used either as analog multiplexers where the signal on a single select line selects one out of four analog inputs, or as four-valued logic multiplexers where the select line and the input lines represent one of four quantized signal values and the output line corresponds to the selected input. Any four-valued logic function can be implemented using only four-valued multiplexers (also known as T-gates), and this T-gate uses just 13 devices (transistors) as compared to 44 devices in CMOS. The design of the T-gate was done using a combination of resonant tunneling diodes (RTD's) and heterojunction bipolar transistors (HBT's) with the folded I-V characteristic (NDR characteristic) of the RTD's providing the compact logic implementation and the HBT's providing the gain and isolation. The application of the same design principles to the design of T-gates using other NDR devices such as resonant tunneling hot electron transistors (RHET's) and resonant tunneling bipolar transistors (RTBT's) is also demonstrated. .

Multipurpose Black-Phosphorus/hBN Heterostructures

“…33 Such NDR peaks have applications in oscillatory circuits, memory devices, and even multi-valued logic. 60 This mode is accessible by changing the bias voltage in the previously discussed regime (Fig. 4.a) from reverse bias to forward bias.…”

Resonant tunneling diodes: models and properties

“…It is what distinguishes the RTD from other interesting quantum device concepts that have been proposed but that show weak, if any, desired phenomena at room temperature. A variety of circuit functions has already been demonstrated, providing proof-of-concept of proposed applications [7]- [10]. The main issue at present is not, in fact, the RTD performance itself but the monolithic integration of RTD's with transistors [high electron mobility transistors (HEMT's) or heterojunction bipolar transistors (HBT's)] into integrated circuits with useful numbers and density of devices.…”

Digital circuit applications of resonant tunneling devices

“…A conventional serial-parallel ripple carry adder that performs 4-bit ripple carry addition on a series of 4-bitwide inputs, with the carry from the most significant bit being clocked and fed back, has a latency of 63 , where is the time required to generate the bit-wise carry (at least three gate delays for each bit) and a throughput of one 64-bit addition every 64 time units. The nanopipelined NDR adder architecture improves the throughput to one 64-bit addition every 16 units, where is the bitwise carry generation delay and is equal to one gate delay instead of three gate delays in conventional logic.…”

“…A similar effect could be achieved by using conventional transistor inverters with varying thresholds. Chan et al [64] describe a multiplevalued logic multiplexer that uses the RTD characteristic to pick specific ranges in the input voltage. Although this design uses RTD resistor branches, as in the previous gate, the RTD branches are all coupled so that when one switches on, the others switch off.…”

“…Chan et al [67] describe a compact oneand two-input multiple-valued logic gate, which can be mask programmed or synthesized following simple rules. The mask programmable design is ideal for use in gate arrays not only because its MVL input and output lines require less space to route than its binary counterparts but also because even the functionality of these gates can be changed at the last mask levels.…”