Input structure for a power amplifier and associated methods
First Claim
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1. An input circuit for an RF power amplifier comprising:
- an input network having a transformer with a primary side and a secondary side, wherein an RF input signal is coupled to the primary side;
a limiting amplifier having an input coupled to the secondary side of the transformer and an output for providing an input to the RF power amplifier; and
a DC feedback loop coupled to the limiting amplifier.
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Abstract
A method and apparatus provides an input structure for a power amplifier. In one example, the input structure has an input network and a predriver circuit to provide an input signal to the power amplifier. The input network includes a transformer for helping to maintain a constant input impedance. The predriver includes a limiting amplifier that provides isolation between the power amplifier and the RF input. A DC feedback circuit is used by the predriver that maintains the DC level of the inverters to a desired level.
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Citations
33 Claims
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1. An input circuit for an RF power amplifier comprising:
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an input network having a transformer with a primary side and a secondary side, wherein an RF input signal is coupled to the primary side;
a limiting amplifier having an input coupled to the secondary side of the transformer and an output for providing an input to the RF power amplifier; and
a DC feedback loop coupled to the limiting amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A predriver circuit for an RF power amplifier comprising:
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an input circuit coupled to an RF input signal; and
a plurality of inverters coupled in series between the input circuit and an input of the RF power amplifier. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of controlling a power amplifier having a predriver circuit comprising:
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sensing the input and output DC levels of the power amplifier;
comparing the sensed DC levels;
creating a feedback signal based on the difference between the sensed DC levels; and
adjusting the DC bias levels in the predriver so that the input and output DC levels of the power amplifier are maintained in a predetermined relationship. - View Dependent Claims (24, 25, 26)
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27. An amplifier comprising:
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a transformer having a primary side and a secondary side, the secondary side having first and second terminals, wherein the primary side is adapted to receive an input signal;
a first switching device having first and second nodes, the first node coupled to the first terminal of the secondary side of the transformer;
a second switching device having third and fourth nodes, the third node coupled to the second terminal of the secondary side of the transformer;
a first capacitance coupled between the second node of the first switching device and the third node of the second switching device; and
a second capacitance coupled between the first node of the first switching device and the fourth node of the second switching device. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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Specification