Three-pin buck converter and four-pin power amplifier having closed loop output voltage control
First Claim
1. A method of supplying power to a load device comprising the steps of:
- a. drawing power from a supply for forming an output voltage wherein the step of drawing power comprises alternately raising a first terminal of a first energy storage element to a first voltage level for charging the first energy storage element and lowering the first terminal of the first energy storage element to a second voltage level for discharging the first energy storage element into a second energy storage element coupled to a second terminal of the first energy storage element thereby forming the output voltage across the second energy storage element, wherein the first voltage level is higher than the output voltage level and the output voltage level is higher than the second voltage level; and
b. forming an error signal that is representative of a difference between a desired output voltage and an average of a voltage level on the first terminal of the first energy storage element for controlling the step of drawing power from the supply.
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Accused Products
Abstract
A circuit for providing a regulated output voltage from a buck converter without directly monitoring the output voltage. The buck converter includes a switch having a first terminal coupled to a supply voltage and a second terminal coupled to a first terminal of an inductor and to a first terminal of a resistive divider. A second terminal of the inductor is coupled to a first capacitor for forming the output voltage across the first capacitor. A voltage formed by the resistive divider is applied to an inverting input of a transconductance amplifier, while a reference voltage is applied to a non-inverting input of the transconductance amplifier. An output of the transconductance amplifier is coupled to a second capacitor for forming an error signal across the second capacitor. The error signal is representative of a difference between the output voltage and a desired output voltage because an average of the voltage formed by the resistive divider is representative of the output voltage. The error signal is compared to a periodic ramp signal by a comparator for forming a switch control signal. Therefore, circuit regulates the output voltage in a feedback loop by monitoring a voltage on the first terminal of the inductor rather than directly monitoring the output voltage. When the circuit is implemented in an integrated circuit package, this results in a savings of one pin. In another aspect, a variable signal is added to, or replaces, the reference voltage such that the circuit functions as a power amplifier.
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Citations
42 Claims
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1. A method of supplying power to a load device comprising the steps of:
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a. drawing power from a supply for forming an output voltage wherein the step of drawing power comprises alternately raising a first terminal of a first energy storage element to a first voltage level for charging the first energy storage element and lowering the first terminal of the first energy storage element to a second voltage level for discharging the first energy storage element into a second energy storage element coupled to a second terminal of the first energy storage element thereby forming the output voltage across the second energy storage element, wherein the first voltage level is higher than the output voltage level and the output voltage level is higher than the second voltage level; and b. forming an error signal that is representative of a difference between a desired output voltage and an average of a voltage level on the first terminal of the first energy storage element for controlling the step of drawing power from the supply. - View Dependent Claims (2, 3, 4, 6)
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5. The method according to claim a 1 wherein the step of forming the error signal comprises a step of charging a capacitor with a current wherein the current is representative of a difference between the voltage level on the first terminal of the first energy storage element and the desired output voltage and wherein the error signal is a voltage level across the capacitor.
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7. An apparatus for drawing power from an input source and supplying a voltage to a load device, comprising:
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a. a first energy storage element having a first terminal and a second terminal; b. a switch for controlling charging of the first energy storage element with a current and discharging the first energy storage element wherein the switch is coupled to the first terminal of the first energy storage element; c. a second energy storage element coupled to the second terminal of the first energy storage element; and d. means for forming an error signal coupled to the first terminal of the first energy storage element. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus for drawing power from an input source and supplying a voltage to a load device, comprising:
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a. a first switch having a first terminal and a second terminal wherein the first terminal is coupled to receive a supply voltage; b. a first energy storage element having a first terminal and a second terminal wherein a first terminal of the first energy storage element is coupled to the second terminal of the first switch; c. a second switch having a first terminal and a second terminal wherein the first terminal of the second switch is coupled to the first terminal of the first energy storage element and the second terminal of the second switch is coupled to a ground node; d. a second energy storage element having a first terminal and a second terminal wherein the first terminal of the second energy storage element is coupled to the second terminal of the first energy storage element and the second terminal of the second energy storage element is coupled to the ground node; e. a voltage monitoring circuit coupled to the first terminal of the first energy storage element and coupled to control the first switch based upon a time average of a voltage at the first terminal of the first energy storage element. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method of supplying power to a load device comprising the steps of:
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a. drawing power from a supply for forming an output voltage wherein the step of drawing power comprises alternately raising a first terminal of a inductor to a first voltage level for charging the inductor and lowering the first terminal of the inductor to a second voltage level for discharging the inductor into a first capacitor coupled to a second terminal of the inductor thereby forming the output voltage across the first capacitor, wherein the first voltage level is higher than the output voltage level and the output voltage level is higher than the second voltage level; and b. forming an error signal that is representative of a difference between a desired output voltage and an average of a voltage level on the first terminal of the inductor for controlling the step of drawing power from the supply. - View Dependent Claims (32, 33, 34, 35)
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36. A method of supplying power to a load device comprising the steps of:
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a. drawing power from a supply for forming an output voltage wherein the step of drawing power comprises alternately raising a first terminal of a first capacitor to a first voltage level for charging the first capacitor and lowering the first terminal of the first capacitor to a second voltage level for discharging the first capacitor into an inductor coupled to a second terminal of the first capacitor thereby forming the output voltage across the inductor, wherein the first voltage level is higher than the output voltage level and the output voltage level is higher than the second voltage level; and b. forming an error signal that is representative of a difference between a desired output voltage and an average of a voltage level on the first terminal of the first capacitor for controlling the step of drawing power from the supply. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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Specification