RF power amplifier with high efficiency and a wide range of gain control
First Claim
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1. A RF power amplifier with high output efficiency and wide range of gain control comprising:
- a first-stage amplifier which comprises a first power transistor, a first bias circuit, and a first bias source, wherein the drain and source of said first power transistor are coupled to a voltage source node and a ground reference node respectively, said first bias source with a fixed voltage level is fed to the gate of said first power transistor via said first bias circuit, thereby allowing said first-stage amplifier to function as a class A or a class AB amplifier, and an input signal coupled to the gate of said first power transistor is amplified and then output at the drain of said first power transistor;
a second-stage amplifier which comprises a second power transistor, a second bias circuit, and a second bias source, wherein the drain and source of said second power transistor are coupled to said voltage source node and said ground reference node respectively, and said second bias source is fed to the gate of said second power transistor via said second bias circuit, and the turn-on drain current of said second power transistor can be adjusted by varying the voltage of said second bias source to achieve output power control, and the output signal of said first-stage amplifier coupled to the gate of said second-stage power transistor is amplified by said second-stage amplifier and then output at the drain of said second power transistor; and
a third-stage amplifier which comprises a third power transistor, a third bias circuit, and a third bias source, wherein the drain and source of said third power transistor are coupled to a voltage source node and a ground reference node respectively, and said third bias source with a fixed voltage level is fed to the gate of said third power transistor via said third bias circuit, thereby allowing said third-stage amplifier to function as a class C amplifier, and the output signal of said second-stage amplifier coupled to the gate of said third-stage power transistor is amplified by said third-stage amplifier and then output at the drain of said third power transistor.
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Abstract
A RF power amplifier with the advantages of high output efficiency and a wide range of gain control is disclosed. By appropriately biasing the power transistor of the power-stage amplifier in the RF power amplifier, the power-stage amplifier functions as a class C amplifier. By varying the bias source of the driving-stage amplifier and keeping the bias sources of the input-stage and power-stage amplifiers at a fixed level, the driving-stage can output a driving signal with a wide range of variable gain. Consequently, the driving signal can be used to drive the power-stage amplifier to obtain highly efficient output and of a wide range of output power gain control.
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Citations
4 Claims
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1. A RF power amplifier with high output efficiency and wide range of gain control comprising:
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a first-stage amplifier which comprises a first power transistor, a first bias circuit, and a first bias source, wherein the drain and source of said first power transistor are coupled to a voltage source node and a ground reference node respectively, said first bias source with a fixed voltage level is fed to the gate of said first power transistor via said first bias circuit, thereby allowing said first-stage amplifier to function as a class A or a class AB amplifier, and an input signal coupled to the gate of said first power transistor is amplified and then output at the drain of said first power transistor; a second-stage amplifier which comprises a second power transistor, a second bias circuit, and a second bias source, wherein the drain and source of said second power transistor are coupled to said voltage source node and said ground reference node respectively, and said second bias source is fed to the gate of said second power transistor via said second bias circuit, and the turn-on drain current of said second power transistor can be adjusted by varying the voltage of said second bias source to achieve output power control, and the output signal of said first-stage amplifier coupled to the gate of said second-stage power transistor is amplified by said second-stage amplifier and then output at the drain of said second power transistor; and a third-stage amplifier which comprises a third power transistor, a third bias circuit, and a third bias source, wherein the drain and source of said third power transistor are coupled to a voltage source node and a ground reference node respectively, and said third bias source with a fixed voltage level is fed to the gate of said third power transistor via said third bias circuit, thereby allowing said third-stage amplifier to function as a class C amplifier, and the output signal of said second-stage amplifier coupled to the gate of said third-stage power transistor is amplified by said third-stage amplifier and then output at the drain of said third power transistor. - View Dependent Claims (2, 3, 4)
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Specification
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Current AssigneeIndustrial Technology Research Institute
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Original AssigneeIndustrial Technology Research Institute
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InventorsSu, Keng-Li, Tao, Kuang-Chung
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Primary Examiner(s)Pascal, Robert
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Assistant Examiner(s)NGUYEN, PATRICIA T
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Application NumberUS08/949,079Time in Patent Office683 DaysField of Search330/277, 330/296, 330/297, 330/310, 330/285, 330/133, 330/134US Class Current330/310CPC Class CodesH03F 1/0244 Stepped controlH03F 2200/408 the output amplifying stage...H03F 3/1935 with junction-FET devicesH03G 1/0011 the device being at least o...
