Patent ID: 7112948

Claim:
A voltage source circuit capable of selectively providing temperature independent and temperature dependent output voltages, comprising: an output terminal which provides said voltage source's output voltage V out ; a base-emitter voltage generating circuit, comprising: a first current source which provides a current i 1 which is selectively set to a value I or a value N*I; a second current source which provides a current i 2 which is selectively set to a value I or a value N*I; first and second pn junctions connected to conduct i 1 and i 2 and thereby establish first and second base-emitter voltages V be1 and V be2 at first and second nodes, respectively, said voltage V be1 set to a value V be1(I) when i 1 =I or to a second value V be1(N*I) when i 1 =N*I, and said voltage V be2 set to a value V be2(I) when i 2 =I or to a second value V be2(N*I) when i 2 =N*I; an amplifier having an output, a non-inverting input and an inverting input, said non-inverting input connected to said second node, said inverting input connected to said first node through an input capacitor having a capacitance C 1 , and said amplifier's output coupled to said output terminal; a feedback capacitor having a capacitance C 2 connected between said inverting input and a third node; a first switch connected between said amplifier's inverting input and a fourth node; a second switch connected between said third node and said fourth node, said fourth node coupled to the output of said amplifier; a third switch connected between said third node and a circuit common point; and a control circuit arranged to selectively operate said switches and said base-emitter voltage generating circuit to produce a temperature independent output voltage or a temperature dependent output voltage.