Patent ID: 7915883
Filing Date: 2011-03-29
Classification: G05F,H03F

Abstract:
1. A constant current circuit that flows a constant current through a circuit connected to a current output terminal, comprising: a first transistor disposed on a current path of said constant current; a second transistor having a control terminal connected in common to that of said first transistor; a first current-voltage converting unit that converts a current flowing through said second transistor into a voltage; a constant current source that generates a reference current; a second current-voltage converting unit that converts said reference current into a voltage; a first error amplifier that receives an input of respective output voltages of said first and second current-voltage converting units, so as to adjust a voltage of the control terminals of said first and second transistors; and a voltage adjusting unit that is connected to one end of said second transistor and makes adjustments so that a voltage at the one end of the second transistor will be approximated to a predetermined reference voltage.