GB1231902A - - Google Patents

Abstract

1,231,902. Automatic voltage control. ITT INDUSTRIES Inc. Feb.19, 1969 [Feb.23,1968] No.8945/69. Heading G3R. A direct voltage regulator, adapted to form a monolithic integrated semi-conductor component, comprises a reference source including a Zener diode ZD and diode FD, as well as a differential amplifier DV and a power stage LS. The elements ZD, FD which are connected between the respective input terminals A, B, of the amplifier DV and the terminals of the regulated voltage source, have opposite temperature co-efficients so that the source of reference voltage has a small temperature response. The common emitter resistor R3 may be replaced by a transistor having a constant base potential, Fig. 3 (not shown). A variable resistor R1 adjusts the value of the regulated voltage. This resistor may be replaced by a further Zener diode providing additional temperature compensation, Fig. 4 (not shown). In another arrangment, the circuit including the power stage LS is inserted through a series resistor between two input terminals, T4 constituting the common emitter load of the amplifier DV. The differential amplifier is symmetrical and includes collector resistors R5, R6. The power stage comprises transistors T6-T9 controlled from the collector of transistor T1. Resistor R10 and capacitor C form a filter circuit to reduce noise. As a substitute for diodes FD5, FD6, the transistor T2 may be connected to a further pair of transistors to increase the time constant of the filter circuit, Fig. 7 (not shown). In a further embodiment, the power stage comprises a pair of transistors of opposite conductivity types connected to the respective collectors of the differential amplifier which is symmetrically loaded thereby. The two power transistors may be each associated with an emitter follower. The chain of diodes is enlarged to ensure correct operation of the differential amplifier, Fig.8 (not shown).