The increasing demand for electronic devices and circuits dedicated to harsh environment applications, specifically high temperature and high power applications, has called for more research dedicated towards silicon carbide (SiC) devices and integrated circuits (ICs). SiC, a wide bandgap semiconductor, is inherently capable of operation in such environments. SiC bipolar transistors are essential for such applications since bipolar devices, unlike MOSFETs, do not have any oxide layer under high electric field, and hence are not prone to reliability issues at high temperatures. In this paper, the design of optimized emitter coupled logic technology circuits using 4H-SiC bipolar transistors is presented. These circuits work over a wide range of temperatures and power supply voltages at high speeds, demonstrating the potential of robust high speed ECL integrated circuits in SiC.