Patent ID: 7952342

Claim:
A constant current source apparatus, comprising: a complementary switching section that selectively outputs a reference voltage or a driving voltage according to a control signal; and a constant current source circuit that causes a constant current determined by the reference voltage to flow to a load in a case where the reference voltage is received from the complementary switching section and cuts off the current flowing to the load in a case where the driving voltage is received from the complementary switching section, wherein the complementary switching section further includes: a first FET in which one of either a source or a drain is connected to the driving voltage, the other source or drain is connected to an output end of the complementary switching section, and a gate receives the voltage according to the control signal; a second FET that switches to an opposite polarity of the first FET, in which one of either a source or a drain is connected to the reference voltage, the other source or drain is connected to the output end of the complementary switching section, and a gate receives the voltage according to the control signal; a bias section that supplies to a gate of the first FET and the second FET a first voltage that turns the first FET on and turns the second FET off or a second voltage that turns the first FET off and turns the second FET on; and a switching circuit that switches between supplying the first voltage to the gate of the first FET and the second FET and supplying the second voltage to the gate of the first FET and the second FET according to the control signal.