Constant current load and level shifter circuitry

A level shifter comprising:

• first and second terminals for receiving first and second operating potentials respectively;
• a level-shifter input terminal;
• a level-shifter output terminal;
• first and second transistors of a first conductivity type, having respective collector electrodes each connected to said first terminal and having respective base and emitter electrodes between which current gains each equal to h.sub.fc are exhibited;
• first-transistor base-connection means for providing a direct-current-conductive path and a prescribed voltage between said level-shifter input terminal and the base electrode of said first transistor;
• first-transistor emitter-connection means for providing a direct-current conductive path and a prescribed voltage between the emitter electrode of said first transistor and said level-shifter output terminal;
• a first current mirror amplifier being of a second conductivity type complementary to said first conductivity type, having an input terminal, having an output terminal connected to said level-shifter input terminal, having a common terminal connected to said first terminal, and exhibiting a current gain of -n between its input and output terminals, n being a positive number;
• second-transistor base-connection means for providing a direct-current-conductive path and a prescribed voltage between the input terminal of said first current mirror amplifier and the base electrode of said second transistor;
• a second current mirror amplifier being of said first conductivity type, having an input terminal, having an output terminal connected to said level-shifter output terminal, having a common terminal connected to said second terminal, and exhibiting a current gain of -n between its input and output terminals;
• and
• second-transistor emitter-connection means for providing a direct-current-conductive path and a prescribed voltage between the emitter electrode of said second transistor and the input terminal of said second current mirror amplifier.