Patent ID: 7504814

Claim:
A current generating apparatus, for generating an output current, comprising: a first current mirror, for generating a first mirror current according to a first bias current and a current mirror ratio; a first bias current generator, coupled to the first current mirror, for providing the first bias current according to a first current and a reference current, the first bias current generator comprising: a first current source, biased by a first bias voltage for providing the first current; and a capacitive device, coupled to the first current source in parallel, for conducting the reference current; a second current mirror, for generating a second mirror current according to a second bias current and the current mirror ratio; a second bias current generator, coupled to the second current mirror, the second bias current generator having a second current source biased by the first bias voltage for generating a second current serving as the second bias current; a third current source, coupled to an output node of the second current mirror, the third current source being biased by a second bias voltage for providing a third current, wherein the second mirror current is equal to the third current; a feedback circuit, coupled to the output node of the second current mirror and the third current source, for tuning the second bias voltage according to a voltage level at the output node of the second current mirror and a target voltage level; and a fourth current source, coupled to an output node of the first current mirror, the fourth current source being biased by the second bias voltage for providing a fourth current, wherein the output current is outputted at the output node of the first current mirror.