Title:
BIAS CIRCUIT
Document Type and Number:
Japanese Patent JPH02306321
Kind Code:
A
Abstract:
PURPOSE:To always hold the gain of a differential amplifier to be constant irrespective of a temperature by permitting a reference voltage impressed on one base of a control transistor to satisfy a specified condition. CONSTITUTION:A bias circuit 12 has the transistor Q3 of the differential ampli fier 1 and a transistor Q4 constituting a current mirror circuit. Since transistors Q5 and Q6 constitute the current mirror circuit, the action current I of the differential amplifier 1 becomes equal to the current quantity of the collector currents of the transistors Q4 and Q6, and it becomes almost equal to the emit ter current of a transistor Q7. A reference voltage Vr impressed on the base of the transistor Q7 is previously set so that it satisfies an expression Vr= Vo-aTo by setting the base/emitter voltage of the transistor Q7 to be Vo and a temperature coefficient to be (a) at a normal temperature To. Thus, the gain of the differential amplifier can be fixed without being influenced by the change of the temperature.
Inventors:
MIURA KATSUNORI
Application Number:
JP12732689A
Publication Date:
December 19, 1990
Filing Date:
May 19, 1989
Export Citation:
Assignee:
SANYO ELECTRIC CO
International Classes:
G05F3/22; H03F1/30; H03F3/45; (IPC1-7): G05F3/22
Attorney, Agent or Firm:
Koji Yasutomi (1 person outside)