Wide-band amplifiers using clipper circuits for reduced harmonics
First Claim
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1. A wideband power amplifier circuit comprising:
- a transistor configured as an amplifier stage of a power amplifier having first, second and third regions where a signal applied to the third region controls current flow between the first and second regions;
a waveform clipping element electrically coupled to the third region, which shapes a peak-to-peak amplitude of the signal applied to the third region, and which reduces a second harmonic of the signal, the waveform clipping element including a voltage variable clipper element controlled by a control voltage generated based at least in part on one or more of a temperature, an output power, or a voltage standing wave ratio under mismatch; and
a wideband filter electrically coupled to an output of the power amplifier to reduce harmonic levels of the signal.
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Abstract
The present invention breaks up the frequency bands which can be filtered by a simple low-loss band-pass or low pass filter. The second harmonic frequency is reduced by use of a non-linear clipper element which controls the driving waveform symmetry and can reduce the harmonics by as much as 5-15 db which makes the filter much simpler and allows the amplifier to remain wide-band. The output waveform from the amplifier is symmetrical or nearly symmetrical.
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Citations
18 Claims
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1. A wideband power amplifier circuit comprising:
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a transistor configured as an amplifier stage of a power amplifier having first, second and third regions where a signal applied to the third region controls current flow between the first and second regions; a waveform clipping element electrically coupled to the third region, which shapes a peak-to-peak amplitude of the signal applied to the third region, and which reduces a second harmonic of the signal, the waveform clipping element including a voltage variable clipper element controlled by a control voltage generated based at least in part on one or more of a temperature, an output power, or a voltage standing wave ratio under mismatch; and a wideband filter electrically coupled to an output of the power amplifier to reduce harmonic levels of the signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A communications system comprising:
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a power amplifier including a transistor having first, second and third terminals where a signal applied to the third terminal controls current flow between the first and second terminals; a waveform clipping circuit electrically coupled to the third terminal, which shapes a peak-to-peak amplitude of the signal applied to the third terminal, and which reduces a harmonic of the signal, the waveform clipping element including a voltage variable clipper element controlled by a control voltage generated based at least in part on one or more of a temperature, an output power, or a voltage standing wave ratio under mismatch; and a filter electrically coupled to an output of the power amplifier to reduce harmonic levels of the signal.
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Specification