Apparatus for generating a current varying with temperature

A two-terminal semiconductive element to be connected to an external DC voltage source to produce through said two terminals a controlled current varying proportionately with absolute temperature of the semiconductive element, comprising:

• first and second transistors each comprising a base, an emitter, and a collector, said transistors having conductive areas of preselected sizes;
• circuit means coupling each of said transistors to both of said terminals to provide for the development of said controlled current flowing from said external voltage source through said terminals to both of said transistors;
• said circuit means including first means activated by said controlled current and coupled to at least one of said transistors for maintaining the relative magnitudes of the currents through said first and second transistors at a value which provides a predetermined ratio different from one between the current densities in the conductive areas of said transistors whereby the .DELTA.V.sub.BE of said two transistors is directly proportional to absolute temperature;
• and
• said circuit means including second means responsive to said .DELTA.V.sub.BE for maintaining the magnitude of said controlled current proportional to said .DELTA.V.sub.BE so that the current flowing through said two terminals is proportional to absolute temperature, said apparatus thereby being adapted to serve as a temperature transducer when connected at one end of a two-wire line supplied at its other end with DC power.