Unbuffered TTL-to-ECL translator with temperature-compensated threshold voltage obtained from a constant-current reference voltage

An unbuffered translating circuit for converting saturated logic voltage signals to ECL signals, comprising:

• a voltage generator which produces a current-source reference voltage V.sub.R having a predetermined negative temperature dependence characteristic over a predetermined temperature range (55.degree. C. to 125.degree. C.);
• a constant current transistor connected to said voltage source for generating a switching current in response to V.sub.R, said switching current being substantially invariant over said predetermined temperature range;
• a pair of switching transistors, one of said switching transistors connected to receive an unbuffered saturated-logic voltage signal and the other of said switching transistors connected to receive a threshold voltage V.sub.T, said switching transistors both being connected at their emitters to said constant current transistor such that said switching current is switched to a respective one of said switching transistors in response to a change in the magnitude of said unbuffered saturated logic signal with respect to the magnitude of V.sub.T ;
• and
• transistor current mirror means connected to said voltage generator for generating V.sub.T in response to V.sub.R such that V.sub.T includes a transistor base-to-emitter voltage component and is substantially invariant over said predetermined temperature range.