Novel vs Conventional Bipolar Logic Circuit Topologies in 4H-SiC

Abstract

Silicon Carbide (SiC) is an attractive candidate for integrated circuits (ICs) in harsh environment applications due to its superior inherent electrical properties. Though current research is geared towards adapting existing silicon based digital logic technologies to 4H-SiC, the true merit of each technology in 4H-SiC has remained unclear. Creating logic technologies specifically for 4H-SiC, taking into account its electrical properties, is an area which remains unexplored. In this paper, we present a novel bipolar logic technology that is designed and optimized for 4H-SiC, and compare its performance with the prevalent bipolar technologies. The results show that the novel logic technology not only compares well with the conventional technologies in performance, but also features simpler design, smaller footprint, and a low transistor count.

Design and Simulation of Bipolar 4H-SiC Memory Architecture for High Temperature Applications

“…The 4H-SiC BJT used in this work has a current gain of 56 and a cut-off frequency of 1.4 GHz, at room temperature. Pursuant to previous publications [1,3,8], and to…”

“…maintain consistency, a constant emitter finger width of 16 µm, and a minimum BJT finger length of 25 μm are used. The effect of temperature on the 4H-SiC BJTs and resistors is accounted for by using different SPICE models for the BJT and considering the change in sheet resistance at each temperature (187.5 Ω/□ at 27 o C and 204.38 Ω/□ at 500 o C) [1]. For all circuit simulations, the rise/fall time of the controlled signals, like WL, is set to 300 ps and the bitline capacitances are set to 15 fF [3].…”

“…Additionally, its mature substrate and fabrication technology and high thermal conductivity enables SiC to withstand elevated temperatures. Though several small scale ICs in 4H-SiC, such as digital logic gates [1], analog circuits [2], have been demonstrated; a memory component that is critical to build a complete electronic module, has only stared recently being explored and developed (bipolar-based [3], JFET-based [4]).…”