GB1373133A - Current regulator - Google Patents

Abstract

1373133 Automatic current regulation PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 6 Dec 1971 [9 Dec 1970] 56519/71 Heading G3X A current regulator includes a first divider circuit having transistors of one conductivity type and supplying two equal currents to a second divider circuit using transistors of the opposite conductivity type. The second divider includes a transistor with its base-emitter path shunted by an impedance and a semi-conductor junction of larger area. In the embodiment shown, a pnp type current divider T 11 , T 12 supplies equal currents I to terminals A, A', connected to terminals B, B'of an npn divider comprising transistors T 13 , T 14 and a resistor R. The transistor T 13 may be a single transistor with a larger emitter area than transistor T 14 , or it may be a number of transistors connected in parallel. Further transistors T 15 , T 16 compensate for current variations due to the base currents of the other transistors. The value of the current I is now closely determined by the setting of the resistor R, independent of the supply voltage. Additional stabilized current outputs may be taken from the collectors of additional transistors T 17 ', T 18 '. For a given resistance R, the current I is directly proportional to the temperature, so that the arrangement may be used as a thermometer. Alternatively, if the stabilized current is passed through a resistor and appropriate semi-conductor junction, a temperature independent voltage source may be produced.