High efficiency power amplifier circuit with wide dynamic backoff range
First Claim
1. A power amplifier circuit comprising:
- a plurality of switches, wherein a first end of each of said plurality of switches is coupled to a corresponding one of a plurality of supply voltages;
a plurality of power amplifiers, wherein a drain of each of said plurality of power amplifiers is coupled to at least one of said plurality of supply voltages through a second end of said corresponding one of said plurality of switches; and
a comparator which responds to an amplitude of a radio frequency signal envelope, said comparator being coupled to said second end of each of said plurality of switches and influencing a mode of each of said plurality of switches, thereby influencing an operating state of each of said plurality of power amplifiers.
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Accused Products
Abstract
A radio frequency signal (FIG. 2, 205) is sampled and the sample is conveyed to a video detector (220). The detected envelope amplitude is sent to an envelope tracking circuit (280), a comparator (230), and an envelope tracking and gate biasing circuit (240). Based on the instantaneous value of the envelope amplitude, the comparator (230) selects one of the available supply voltages (340) via switch drivers (270). The selected one of the available supply voltages (340) is adjusted by the envelope tracking circuit (280) and the resulting voltage output (282) is supplied to the drains of the power amplifiers (390), thus enabling operation near saturation. As the instantaneous value of the envelope amplitude increases, the comparator (230) selects higher supply voltages (340) which increases the voltage conveyed to the power amplifiers (390), thereby increasing their power output. In order to maintain constant gain performance, the envelope tracking and gate biasing circuit (240) modifies the gate bias inversely with the changes the drain voltage.
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Citations
20 Claims
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1. A power amplifier circuit comprising:
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a plurality of switches, wherein a first end of each of said plurality of switches is coupled to a corresponding one of a plurality of supply voltages; a plurality of power amplifiers, wherein a drain of each of said plurality of power amplifiers is coupled to at least one of said plurality of supply voltages through a second end of said corresponding one of said plurality of switches; and a comparator which responds to an amplitude of a radio frequency signal envelope, said comparator being coupled to said second end of each of said plurality of switches and influencing a mode of each of said plurality of switches, thereby influencing an operating state of each of said plurality of power amplifiers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of amplifying a composite signal in a power amplifier circuit, comprising the steps of:
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determining an envelope amplitude of a radio frequency signal; comparing said envelope amplitude with a plurality of voltage levels; selecting one of a plurality of supply voltages based on said comparing step; coupling said one of said plurality of supply voltages to a plurality of power amplifiers based on selecting step; and amplifying said radio frequency signal using at least one of said plurality of power amplifiers. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. In a communications node, a method for producing an amplified composite signal, comprising the steps of:
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combining a plurality of communications signals in a power amplifier circuit to form a composite radio frequency signal; selecting a supply voltage based on an envelope amplitude of said composite radio frequency signal; selecting a power amplifier based on an envelope amplitude of said composite radio frequency signal; and amplifying said composite radio frequency signal based on a portion of said envelope amplitude of said composite radio frequency signal to form said amplified composite signal. - View Dependent Claims (17, 18, 19, 20)
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Specification