Linear voltage regulator using adaptive biasing
AssigneeLinfinity Microelectronics
InventorsAli Enayat Zadeh, Yung-I Chang
Life of this patent
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Abstract
A linear voltage regulator, such as a low-dropout regulator, supplies power to one or more digital circuits within a computer system. The low-dropout regulator provides a substantially constant output voltage independent of loading conditions. The low-dropout regulator is biased at a relatively low operating current for steady-state operation to improve power efficiency of the low-dropout regulator. During a loading condition change, an adaptive biasing circuit senses the loading condition change and provides additional biasing current to momentarily increase the operating current of the low-dropout regulator to improve transient response.
Claims18
A linear voltage regulator which accepts a direct current input voltage at an input terminal and provides a direct current output voltage at an output terminal, the linear voltage regulator comprising:
- a power transistor connected in series between the input terminal and the output terminal of the linear voltage regulator, wherein the power transistor provides a load current to the output terminal at a selected output voltage;
- a feedback network configured to sense the output voltage, wherein the feedback network generates a feedback voltage;
- a control circuit configured to receive the feedback voltage and to control the power transistor to maintain the selected output voltage at a substantially constant level;
- and
- a current sense circuit configured to sense the load current using a sensing transistor coupled to a control terminal of the power transistor, wherein the operating current of the control circuit increases in response to transient increases in the load current.
A low-dropout regulator which accepts an input voltage at an input terminal and provides an output voltage at an output terminal, the voltage regulator comprising:
- a pass transistor connected between the input terminal and the output terminal of the voltage regulator, wherein the pass transistor conducts an output current;
- a feedback network that senses the output voltage, wherein the feedback network provides a feedback voltage;
- a control circuit that receives the feedback voltage and responds to changes in the feedback voltage by adjusting the pass transistor to conduct a different output current, wherein the control circuit is biased at a relatively low steady-state operating current;
- and
- an adaptive biasing circuit that senses the output current with a transistor coupled to a control terminal of the pass transistor and provides additional operating current to the control circuit using current mirror transistors during a transient increase in the output current.
A method of biasing a linear voltage regulator, the method comprising:
- biasing the linear voltage regulator at a relatively low operating current for steady-state operations;
- detecting transients in a load current using a sensing transistor;
- and
- providing additional operating current to the linear voltage regulator with current mirror transistors to result in relatively high operating current during the transients.
A method of biasing a linear voltage regulator so as to provide a selected direct current output voltage from a direct current input voltage, the method comprising:
- providing an output current at an output terminal of the linear voltage regulator at the selected output voltage;
- sensing the output voltage and generating a feedback voltage;
- utilizing the feedback voltage to maintain the selected output voltage at a substantially constant level;
- sensing a loading condition change via a surge in the output current and generating a mirrored current proportional to the surge in the output current;
- and
- increasing a steady-state biasing current of the linear voltage regulator with the mirrored current.
A linear voltage regulator which accepts a direct current input voltage at an input terminal and provides a direct current output voltage at an output terminal, the linear voltage regulator comprising:
- means for providing a load current to the output terminal at a selected output voltage;
- means for sensing the output voltage and generating a corresponding feedback voltage;
- means for receiving the feedback voltage and maintaining the selected output voltage at a substantially constant level;
- and
- means for actively sensing a loading condition change and to thereby increase an operating current of the linear voltage regulator.
Dependencies are inferred from the claim text.