Method and circuit for low power voltage reference and bias current generator
AssigneeAnalog Devices, Inc.
InventorStefan Marinca
Life of this patent
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Abstract
Circuits for generating a PTAT voltage as a base-emitter voltage difference between a pair of bipolar transistors. The circuits may form unit cells in a cascading voltage reference circuit that increases the PTAT voltage with each subsequent stage. The bipolar transistors are controlled using a biasing arrangement that includes an MOS transistor connected to a current mirror that provides the base current for the bipolar transistors. A voltage reference is formed by combining a PTAT voltage and a CTAT voltage at the last stage. The voltage reference may be obtained from the voltage at an emitter of one of the bipolar transistors in the last stage.
Claims20
A base-emitter voltage difference circuit, comprising:
- a first bipolar transistor and a second bipolar transistor sharing a common base;
- a first amplifier stage that controls a collector voltage of the first bipolar transistor and generates a base current of the first bipolar transistor and the second bipolar transistor;
- and
- a second amplifier stage that controls a collector voltage of the second bipolar transistor and comprises one or more active circuit elements arranged to generate a proportional to absolute temperature (PTAT) voltage as a difference between a base-emitter voltage of the first bipolar transistor and a base-emitter voltage of the second bipolar transistor.
A cascading circuit, comprising:
- a plurality of unit cells connected in a cascaded fashion, each unit cell comprising:
- a first bipolar transistor and a second bipolar transistor sharing a common base;
- a first amplifier stage that controls a collector voltage of the first bipolar transistor and generates a base current of the first bipolar transistor and the second bipolar transistor;
- and
- a second amplifier stage that controls a collector voltage of the second bipolar transistor and generates a proportional to absolute temperature (PTAT) voltage as a difference between a base-emitter voltage of the first bipolar transistor and a base-emitter voltage of the second bipolar transistor.
A method, comprising:
- generating a proportional to absolute temperature (PTAT) voltage using a first amplifier stage and a second amplifier stage of a circuit in which a first bipolar transistor and a second bipolar transistor share a common base, wherein the first amplifier stage controls a collector voltage of the first bipolar transistor and generates a base current of the first bipolar transistor and the second bipolar transistor, and wherein the second amplifier stage controls a collector voltage of the second bipolar transistor and generates the PTAT voltage as a difference between a base-emitter voltage of the first bipolar transistor and a base-emitter voltage of the second bipolar transistor, the second amplifier stage electrically connected to an emitter of the second bipolar transistor.
Dependencies are inferred from the claim text.