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US 8,797,772 B2Granted
Low noise voltage regulator
AssigneeTexas Instruments Incorporated
InventorsTeddy D. Thomas, Gregory Stewart Waterfall
Life of this patent
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Abstract
A low noise voltage regulator generally includes an output switching stage and an amplifier, both of which contribute current to produce an output voltage at a substantially constant level. The amplifier produces a current that is based on a difference between a reference voltage and a feedback of the output voltage. The current from the amplifier (and optionally also from a current ramp generator) counterbalances the current from the output switching stage to maintain the output voltage at the substantially constant level. The output switching stage is controlled in response to a level of the counterbalancing current.
Claims19
An electronic device comprising:
- an output switching stage that produces a first current, the first current contributes a major portion of an output current;
- an amplifier connected to the output switching stage, the amplifier receives a feedback of an output voltage and produces a second current that is based on a difference between a reference voltage and the feedback of the output voltage, the second current forms at least part of a counterbalancing current that contributes a minor portion of the output current, the counterbalancing current, combined with the first current, maintains the output voltage at a substantially constant level;
- and
- a current sensor that detects a level of the counterbalancing current;
- and wherein the output switching stage is controlled in response to the level of the counterbalancing current, and wherein
- the output switching stage is switched on when the counterbalancing current increases to an upper threshold level;
- the output switching stage is switched off when the counterbalancing current decreases to a lower threshold level that is below the upper threshold level;
- when the output switching stage is switched on, the first current increases and the counterbalancing current decreases;
- when the output switching stage is switched off, the first current decreases and the counterbalancing current increases;
- and
- the increasing and decreasing of the first current and the counterbalancing current maintain the output voltage at about a desired voltage level.
8 more elements
An electronic device comprising:
- an output switching stage that produces a first current, the first current contributes a first portion of an output current at an output voltage;
- an output control amplifier connected to the output switching stage, the output control amplifier receives a feedback of the output voltage at a negative input and a reference voltage at a positive input, the output control amplifier produces a second current that is relative to a difference between the reference voltage and the feedback of the output voltage, the second current forms at least part of a counterbalancing current that contributes a second portion of the output current, the second portion is smaller than the first portion, the first current and the counterbalancing current alternate ramping up and down substantially out of phase with each other;
- a current sensor that detects a level of the counterbalancing current;
- and
- a control circuit connected to the current sensor and the output switching stage to control the output switching stage in response to the detected level of the counterbalancing current, the control circuit and the current sensor are configured to minimize the contribution of the counterbalancing current to the output current, wherein
- the output switching stage is switched on when the counterbalancing current increases to an upper threshold level;
- the output switching stage is switched off when the counterbalancing current decreases to a lower threshold level that is below the upper threshold level;
- when the output switching stage is switched on, the first current increases and the counterbalancing current decreases;
- when the output switching stage is switched off, the first current decreases and the counterbalancing current increases;
- and
- the increasing and decreasing of the first current and the counterbalancing current maintain the output voltage at about a desired voltage level.
8 more elements
A method comprising:
- generating a first current by an output switching stage, the first current exhibits a ripple and contributes a major portion of an output current;
- generating a second current by an amplifier based on a difference between an output voltage and a reference voltage, the second current contributes a minor portion of the output current and exhibits a counterbalancing ripple that, combined with the ripple of the first current, maintains the output voltage at a substantially constant level;
- controlling the output switching stage to increase the first current in response to detecting a level of a detected current above a first level, the second current forms at least a part of the detected current;
- and
- controlling the output switching stage to decrease the first current in response to detecting the level of the detected current below a second level;
- switching the output switching stage on when the counterbalancing current increases to an upper threshold level so that the first current increases and the counterbalancing current decreases;
- switching the output switching stage off when the counterbalancing current decreases to a lower threshold level that is below the upper threshold level so that the first current decreases and the counterbalancing current increases;
- wherein the increasing and decreasing of the first current and the counterbalancing current maintain the output voltage at about a desired voltage level.
5 more elements
Dependencies are inferred from the claim text.