Complementary MOS to emitter-coupled logic level converter - gives output voltages from three-stage bipolar level-shifter referred to fixed potential

摘要

A current-switching stage (1) in the emitter circuit of a bipolar transistor (4) drives a level-shifting stage (2) contg. the base-to-emitter paths of cascaded bipolar transistors (13-15). The base of the first transistor (4) is returned to a fixed reference voltage (V1) which exceeds the emitter supply voltage (VCC) by four times the drop across a diode. The high CMOS level of input (5) causes an n-channel MOSFET (11) to shunt the resistance-diode combination (10,12). The low CMOS level cuts-off the MOSFET so that the resistance (10) drops about 0.8 V to the ECL signal level. ADVANTAGE - Function of following emitter-coupled logic stages is not jeopardised by relatively small fluctuations of supply voltage.