ECL to GaAs logic level shift interface circuit

A compound semiconductor integrated circuit adapted to provide an interface with respect to an internal circuit which is driven by first and second power source voltages and operates responsive to a logic signal having a predetermined logic level which is different from an emitter-coupled logic level, said compound semiconductor integrated circuit comprising:

• an input terminal for receiving an input logic signal having the emitter-coupled logic level;
• input circuit means, coupled to said input terminal and driven by the first power source voltage and a third power source voltage, for receiving the input logic signal via said input terminal, said input circuit means including a differential amplifier circuit which is driven by the first and third power source voltages, and which outputs positive and inverted phase logic signals in response to the input logic signal;
• and
• output circuit means, coupled to said input circuit means and driven by the first and second power source voltages, for converting an output signal of said input circuit means into a signal having the predetermined logic level, said output circuit means including push-pull circuit means, coupled to the differential amplifier circuit and driven by the first and second power source voltages, for generating the output of the output circuit means responsive to the positive and inverted phase logic signals output from the differential amplifier circuit,
• said second power source voltage being lower than the first power source voltage,
• said third power source voltage being different from the second power source voltage and being lower than the first power source voltage,
• said output circuit means supplying an output thereof to the internal circuit.