Zero power start-up circuit for self-bias circuit
AssigneeMicron Technology, Inc.
InventorHagop A. Nazarian
Life of this patent
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Abstract
An improved start-up circuit and method for self-bias circuits is described that applies a start-up voltage and current to a self-bias circuit to initialize its operation in its desired stable state. Once the self-bias circuit converges to its desired state of operation a start-up voltage reference/voltage clamping circuit shuts off current flow to the self-bias circuit and the start-up circuit enters a low power mode of operation to reduce its overall current and power draw. This allows for embodiments of the present invention to be utilized in portable and/or low power devices where low power consumption is of increased importance. In one embodiment of the present invention, a band-gap voltage reference circuit is initiated utilizing a start-up circuit.
Claims32
A band-gap voltage reference circuit, comprising:
- a current mirror coupled to an upper power rail;
- a first current path having a first bipolar junction transistor with a collector coupled to the current mirror through a first resistor, and an emitter coupled to a lower power rail, wherein the collector is coupled to a base of the first bipolar transistor;
- a second current path having second bipolar junction transistor and a second resistor, wherein a collector of the second bipolar junction transistor is coupled to the current mirror, a base of the second bipolar junction transistor coupled to the base of the first bipolar transistor, and where the second resistor is coupled between an emitter of the second bipolar junction transistor and the lower power rail;
- and
- a start-up circuit having an output, wherein the output is coupled to the first current path,
- the start-up circuit comprising,
- a start-up circuit current mirror,
- a start-up voltage reference coupled to a first output of the start-up circuit current mirror, and
- an output transistor coupled between a second output of the start-up circuit current mirror and the output of the start-up circuit, wherein an input of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference and where the output transistor is controlled by the voltage difference between a voltage of the start-up voltage reference and a voltage of the first current path,
- wherein the start-up circuit is adapted to turn off when the voltage of the output of the start-up circuit coupled to the first current path is greater than the start-up voltage reference.
A memory device, comprising:
- an array of memory cells;
- and
- a band-gap voltage reference circuit, comprising:
- a current mirror coupled to an upper power rail;
- a first current path having a first bipolar junction transistor with a collector coupled to the current mirror through a first resistor, and an emitter coupled to a lower power rail, wherein the collector is coupled to a base of the first bipolar transistor;
- a second current path having second bipolar junction transistor and a second resistor, wherein a collector of the second bipolar junction transistor is coupled to the current mirror, a base of the second bipolar junction transistor coupled to the base of the first bipolar transistor, and where the second resistor is coupled between an emitter of the second bipolar junction transistor and the lower power rail;
- and
- a start-up circuit having an output, wherein the output is coupled to the first current path, the start-up circuit comprising,
- a start-up circuit current mirror,
- a start-up voltage reference coupled to a first output of the start-up circuit current mirror, and
- an output transistor coupled between a second output of the start-up circuit current mirror and the output of the start-up circuit, wherein an input of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference and where the output transistor is controlled by the voltage difference between a voltage of the start-up voltage reference and a voltage of the first current path,
- wherein the start-up circuit is adapted to turn off when the voltage of the output of the start-up circuit is greater than the start-up voltage reference.
A system, comprising:
- a processor coupled to a memory device, wherein the memory device comprises,
- an array of memory cells;
- and
- a band-gap voltage reference circuit, comprising:
- a current mirror coupled to an upper power rail;
- a first current path having a first bipolar junction transistor with a collector coupled to the current mirror through a first resistor, and an emitter coupled to a lower power rail, wherein the collector is coupled to a base of the first bipolar transistor;
- a second current path having second bipolar junction transistor and a second resistor, wherein a collector of the second bipolar junction transistor is coupled to the current mirror, a base of the second bipolar junction transistor coupled to the base of the first bipolar transistor, and where the second resistor is coupled between an emitter of the second bipolar junction transistor and the lower power rail;
- and
- a start-up circuit having an output, wherein the output is coupled to the first current path, the start-up circuit comprising,
- a start-up circuit current mirror,
- a start-up voltage reference coupled to a first output of the start-up circuit current mirror, and
- an output transistor coupled between a second output of the start-up circuit current mirror and the output of the start-up circuit, wherein a control gate of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference and where the output transistor is controlled by the voltage difference between a voltage of the start-up voltage reference and a voltage of the first current path,
- wherein the start-up circuit is adapted to turn off when the voltage of the output of the start-up circuit coupled to the first current path is greater than the start-up voltage reference.
A method of operating a start-up circuit, comprising:
- outputting a start-up current from an output of the start-up circuit for a self-bias circuit upon power-up, where the start-up current is from a current mirror source of a start-up circuit and where the start-up current is injected into a current path of the self-bias circuit;
- capacitively coupling the voltage on gates of transistors in the current mirror to a low power rail during power-up with a selected capacitance;
- halting output of the start-up current when a voltage of the current path of the self-bias circuit is greater than a start-up voltage reference;
- and
- halting operation of the current mirror upon halting output of the start-up current.
A method of starting a self-bias circuit, comprising:
- injecting a start-up current from a start-up current mirror upon power-up into a current path of a central circuit of a self-bias circuit with two or more stable states of operation, wherein the injected start-up current operates to bootstrap the self-bias circuit into a desired state of operation;
- capacitively coupling gates of transistors of the current mirror to a low power rail during power-up with a selected capacitance;
- halting injection of the start-up current when a voltage of the current path of the central circuit is greater than a start-up voltage reference;
- and
- halting operation of the start-up current mirror upon halting injection of the start-up current.
A method of starting a self-bias circuit, comprising:
- injecting a start-up current from a start-up current mirror upon power-up into a feedback loop of a self-bias circuit that utilizes feedback and has two or more stable states of operation wherein the injected start-up current operates to bootstrap the feedback of the self-bias circuit into a desired state of operation;
- capacitively coupling gates of transistors of the current mirror to a low power rail during power-up with a selected capacitance;
- halting injection of the start-up current when a voltage of the feedback loop of the self-bias circuit is greater than a voltage of a start-up voltage reference;
- and
- halting operation of the start-up current mirror upon halting injection of the start-up current.
A method of operating a band-gap voltage reference that comprises a current mirror coupled to an upper power rail, a first current path having a first bipolar junction transistor with a collector coupled to the current mirror through a first resistor, and an emitter coupled to a lower power rail, wherein the collector is coupled to a base of the first bipolar transistor, a second current path having second bipolar junction transistor and a second resistor, wherein a collector of the second bipolar junction transistor is coupled to the current mirror, a base of the second bipolar junction transistor coupled to the base of the first bipolar transistor, and where the second resistor is coupled between an emitter of the second bipolar junction transistor and the lower power rail, and a start-up circuit having an output, wherein the output is coupled to the first current path, the start-up circuit comprising, a start-up circuit current mirror, a start-up voltage reference coupled to a first output of the start-up circuit current mirror, and an output transistor coupled between a second output of the start-up circuit current mirror and the output of the start-up circuit, wherein a gate of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference, comprising:
- operating the start-up circuit to provide a start-up current from the output of the start-up circuit to the first current path until a voltage of the first current path coupled to the output of the start-up circuit is greater than a voltage of the start-up voltage reference.
Dependencies are inferred from the claim text.