Title:
CONSTANT CURRENT CIRCUIT
Document Type and Number:
Japanese Patent JP3052818
Kind Code:
B
Abstract:
PROBLEM TO BE SOLVED: To obtain a constant current over a wide voltage area by providing a current sink circuit increasing a drain current at a low voltage and a current source circuit supplying a correction current at a high voltage to generate a constant current at a small voltage region without the use of a complicated circuit.
SOLUTION: The circuit is provided with a current control circuit consisting of a PMOS TR M1 and a resistor R1 and a current sink circuit 6 consisting of NMOS TRs M2, M3 and a resistor R2 and supplying a sink current to a current control circuit 1 at a low voltage. Furthermore, a current source circuit 7 consisting of PMOS TRs M4, M5 and resistors R3-R5 and supplying a current at a high voltage, and a reference power supply 8 supplying a reference voltage V whose voltage is a voltage between a positive power supply D and a negative power supply E. When the reference voltage V is low, a gate-source voltage of the TR M1 is increased to increase a reference current I. When the reference voltage V is increased, the operation of the current sink circuit 6 is stopped at a certain voltage.
Inventors:
Iyoda, Moritaka
Application Number:
JP1996000005904
Publication Date:
April 07, 2000
Filing Date:
January 17, 1996
Export Citation:
Assignee:
NEC CORP
International Classes:
G01K11/00; G01K5/52; G01K11/12; G01K11/00; G01K5/00; (IPC1-7): H03F3/345; G05F3/24