Differential amplifier

A differential amplifier comprising:

• an input amplifier stage comprising a first pair of npn transistors having collector electrodes connected to a first voltage supply, base electrodes forming input terminals of said differential amplifier and emitter electrodes, and a second pair of pnp transistors each having an emitter electrode connected to the emitter electrode of a corresponding one of said first pair of npn transistors, a base electrode and a collector electrode;
• a third pair of pnp transistors each having a base electrode connected to its collector electrode and having substantially the same operating characteristics as those of said second pair of pnp transistors, each transistor of said third pair of pnp transistors having an emitter electrode connected to the emitter of a corresponding one of said second pair of pnp transistors, each transistor of said third pair of pnp transistors having a base electrode connected to the base electrode of the corresponding one of said second pair of pnp transistors, thereby providing bias currents through said second pair of pnp transistors and compensating for changes in operating characteristics of said second pair of pnp transistors due to temperature fluctuations;
• bias circuit means connected to the base electrodes of said third pair of pnp transistors for supplying bias currents therein;
• load circuit means connected to the collector electrodes of said second pair of pnp transistors for providing at one of the collector electrodes of said second pair of pnp transistors, differential voltage changes having a correspondence to the variations between input signals applied to said input terminals;
• and
• output means connected to the collector electrode of one of said second pair of pnp transistors for deriving said differential voltage changes as an output signal of said differential amplifier.