10-GHz Operation of Multiple-Valued Quantizers Using Resonant-Tunneling Devices

We study ultrafast operation of multiple-valued quantizers composed of resonant-tunneling diodes (RTDs) and high electron mobility transistors (HEMTs). The operation principle of these quantizers is based on the monostable-multistable transition logic (MML) of series-connected RTDs. The quantizers are fabricated by monolithically integrating InP-based RTDs and 0.7-μm-gate-length HEMTs with a cutoff frequency of 40GHz. To perform high-frequency experiments, an output buffer and termination resistors are attached to the quantizers, and the quantizers are designed to accommodate high-frequency input signals. Our experiments show that both ternary and quaternary quantizers can operate at clock frequencies of 10GHz and at input frequencies of 3GHz. This demonstrates the potential of applying RTD-based multiple-valued quantizers to high-frequency circuits. key words: resonant-tunneling diodes, HEMT, multiple-valued logic, negative differential resistance