A biasing circuit for multifunction bipolar integrated circuits

Claim 1

A bias circuit for multifunction integrated circuits, apt to generate fixed and programmable currents and the voltages required by the functions (Fl....F4) of the integrated circuit, characterized in that said fixed and programmable currents are obtained from a common reference voltage (V R ) generated inside the bias circuit and depending on the band-gap of the semiconductor by which the individual circuit elements are manufactured; in that for the generation of said fixed currents, said common reference voltage, raised to the level necessary to drive all the functions, is applied to the bases of a plurality of common-collector transistors (Q12....Q15) at whose emitters voltages are present to be applied to generators generating the fixed currents for the various functions (Fl....F4) of the integrated circuit; and in that, in order to obtain said programmable currents, a low-programmation current is generated through a programmation resistor (Re) external to the integrated circuit, and said current is raised to the level required by the individual functions of the integrated circuit to be biased through a double amplification, the first amplification being obtained through a floating NPN mirror (Q23, Q24, Q25, R12, R13) with base current compensation, and the second amplification being obtained through a multiple-output NPN mirror (Q26, Q27, Q28, Q29, Q30, Q31, R14, R15, R16, R17, R18, R19) whose input element is connected the output of that floating mirror (Q23, Q24, Q25, R12, R13) and whose output elements (Q28, R16; Q29, R17; Q30, R18; Q31, R19) are connected to the individual functions of the integrated circuit.