MOS Bandgap reference
AssigneeMotorola, Inc.
InventorHorst Leuschner
Life of this patent
Estimating the term…
Abstract
A bandgap voltage reference source is provided which is temperature stable or temperature controlled and can be made by standard CMOS process. The reference has two substrate bipolar transistors with the emitter current density of one of the transistors being larger than the emitter current density of the other transistor. The transistors are used as emitter followers having resistors in their emitter circuits from which an error voltage is obtained. The error voltage is amplified through a differential or operational amplifier. Through the amplifier or through a resistor network, an output voltage higher or lower, respectively, than the bandgap voltage can be obtained. The output voltage can be made to have a positive, negative, or zero temperature coefficient.
Claims8
A bandgap reference circuit comprising:
- a first voltage potential terminal;
- a second voltage potential terminal;
- a first transistor having a base, a collector, and an emitter, the collector being coupled to the first voltage potential terminal;
- a second transistor having a base, a collector, and an emitter, the collector of the second transistor being coupled to the first voltage potential terminal, the emitter current density of the first transistor being larger than the emitter current density of the second transistor;
- a first resistor coupled between the emitter of the first transistor and the second voltage potential terminal;
- a second and a third resistor connected in series and forming a node therebetween, the second and third resistors being coupled in series between the emitter of the second transistor and the second voltage potential terminal;
- an amplifier having field effect transistors and also having a first and a second input and an output, the first input being coupled to the emitter of the first transistor, and the second input being coupled to the node between the second and third resistors, the output of the amplifier providing the bandgap reference voltage, and the output being coupled to the bases of the first and second transistors.
A reference circuit coupled between a first and a second voltage terminal, comprising:
- a first substrate bipolar transistor having a base, an emitter, and a collector, the collector being coupled to the first voltage terminal;
- a second substrate bipolar transistor having a base, an emitter, and a collector, the collector of the second transistor being coupled to the first voltage terminal, the emitter current density of the first transistor being larger than the emitter current density of the second transistor;
- a first resistor coupled between the emitter of the first transistor and the second voltage terminal;
- a second and a third resistor coupled in series between the emitter of the second transistor and the second voltage terminal, the second and third resistors forming a node therebetween;
- and a differential amplifier having an output and a first and a second input, the first input being coupled to the emitter of the first transistor, the second input being coupled to the node between the second and third resistors, and the output providing a temperature stable reference voltage.
Dependencies are inferred from the claim text.