Patent ID: 7902808
Filing Date: 2011-03-08
Classification: G05F

Abstract:
1. A constant current circuit for supplying a constant current to each of a plurality of operating circuits, comprising: a current mirror input transistor through which an input-side constant current flows; and a plurality of current mirror output transistors that each have a control end that is commonly connected to a control end of the current mirror input transistor, and each of the plurality of current mirror output transistors supply an output-side constant current to a corresponding one of the plurality of operating circuits, wherein the output-side constant current corresponds in magnitude to the input-side constant current, wherein at least one of the plurality of current mirror output transistors is equipped with a low pass filter for removing a high-frequency component contained in the respective output-side constant current, wherein the low pass filter comprises two resistors and a capacitor, wherein the two resistors are connected in series at a common node, one of the two resistors connected in series is connected to a collector node of at least one of the plurality of current mirror output transistors, one end of the capacitor is connected to the common node, and one end of the capacitor is connected to a ground node, and wherein the low pass filter removes the high-frequency component in the output-side current.