ABSTRACT
Abstract. A new CML-type monostable/bistable logic element IC is fabricated using monolithically integrated resonant tunnelling diodes (RTDs) and InP/InGaAs Heterojunction Bipolar Transistors (HBTs). The D flip-flop function of the fabricated circuit is confirmed up to 20 Gbps at room temperature. This result indicates the potential of the RTD/HBT technology for high-speed logic applications
1. Introduction Resonant Tunnelling Diodes (RTDs) exhibit the extremely high-speed switching time [1] with the unique Negative Differential Resistance (NDR) characteristics based on quantum transport phenomena. Due to these features, logic circuits based on RTD have low circuit complexity and low-power consumption with high speed operation. Therefore, these logic circuits have been widely investigated as a promising candidate for future high speed digital ICs [2]. Among them, MOnostable-Bistable Logic transition Element (MOBILE) ICs, which consist o f two resonant tunnelling diodes in series and one 3-terminal device for current modulation, have been developed for high speed operation mainly based on the HEMT/RTD technology [3]. However, HBTs, which have an advantage of enhancement-type [4], have not been widely used in MOBILE ICs compared with HEMT based technologies. Up to date, there has been no report on RTD/HBT ICs operating at a frequency higher than 3 Gbps [5].
