Title:
CONSTANT CURRENT CIRCUIT
Document Type and Number:
Japanese Patent JPS62293327
Kind Code:
A
Abstract:
PURPOSE:To obtain a constant current circuit which is stable enough to the temperature change by combining the circuits having the tendencies adverse to each other against the temperature change. CONSTITUTION:In the 1st closed loop circuit 41 the transistors Tr 1 and 2 are actuated in an intensive reverse area and the Tr 7 and 8 are actuated in a weak reverse area, respectively. Then the current value flowing in the circuit 41 increases by about 10% at 100 deg.C compared with -50 deg.C. While the current flowing in the 2nd closed loop circuit 42 where the Tr 5, 6, 10 and 11 are actuated in an intensive reverse state increases about 10% at -50 deg.C compared with 100 deg.C. The current of a Tr 3 is decided by the ratio of gain coefficients between the Tr 1 and 3; while the current of a Tr 4 is decided by the ratio of gain coefficients between the Tr 5 and 4. Therefore the levels of the current flowing to a Tr 9 are approximately equal to each other between -50 deg.C and 100 deg.C by securing an equal gain coefficient between both Tr 3 and 4.
Inventors:
TAKAI CHIZUKO
Application Number:
JP13666786A
Publication Date:
December 19, 1987
Filing Date:
June 11, 1986
Export Citation:
Assignee:
NEC CORP
International Classes:
G05F3/24; (IPC1-7): G05F3/24
Attorney, Agent or Firm:
Uchihara Shin