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AssigneePanasonic Intellectual Property Management Co., Ltd.
InventorsTakashi Uno, Hikaru Ikeda, Kazuhiro Yahata, Motoyoshi Iwata, Hiroshi Naitou, Tomohide Kamiyama
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A radio frequency power amplifier includes: an amplifying element which amplifies an input signal and outputs the signal from an output terminal; and an output load circuit which includes a first resonant circuit and a second resonant circuit that are connected to the output terminal. The first resonant circuit has a resonance frequency higher than the frequency of the second harmonic of the input signal, and the second resonant circuit has a resonance frequency lower than the frequency of the third harmonic of the input signal. The output load circuit has such an impedance looking from the output terminal that a phase of a reflection coefficient at the second harmonic of the input signal is greater than 180 degrees and less than 360 degrees, and a phase of a reflection coefficient at the third harmonic of the input signal is greater than 0 degrees and less than 180 degrees.
A radio frequency power amplifier which performs class F operation, comprising:
A radio frequency power amplifier which performs an inverse class F operation, comprising:
Dependencies are inferred from the claim text.
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With semiconductor devices only: with field-effect devices
Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation: in transistor amplifiers
Modifications of input or output impedances, not otherwise provided for: using inductive elements
Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators: using FET's, e.g. GaAs FET's
About 5 years 9 months of term left · ends 22 Jul 2032 (estimated)
The present invention relates to radio frequency power amplifiers, and in particular, to a radio frequency power amplifier suitable for use as a class F amplifier circuit or an inverse class F amplifier circuit which controls harmonics.
A radio frequency power amplifier has such input and output characteristics that (i) when input power is low, a signal is amplified while maintaining constant gain in a linear region, and (ii) as the input power increases and gain begins to decrease, output power becomes constant in a saturation region regardless of the input power level.
For example, a Doherty amplifier is known as a representative technique for increasing the power added efficiency (PAE) in the linear region. Furthermore, for example, a class F amplifier is known as a technique for increasing the PAE in the saturation region.
[FIG. 1A]
FIG. 1A is a circuit diagram of a radio frequency power amplifier according to Embodiment 1.
[FIG. 1B]
(Knowledge of the Inventors)
In the technique according to PTL 2, a load circuit of a radio frequency power amplifying circuit is designed considering parasitic capacitance between the drain and the source of a FET serving as an amplifying element, to increase PAE of the radio frequency power amplifying circuit.
However, the inventors have found out in their studies that consideration of only the parasitic capacitance between the drain and the source is insufficient for a high-power radio frequency power amplifier. To achieve high-power operation, the FET needs to drive a large amount of current. This requires the size of the FET (gate width) to significantly increase. The increase in the size of the FET decreases the impedance of the FET. The inventors have found out that sufficient increase in efficiency cannot be achieved when the impedance of the FET is small, because the influences of the parasitic inductance of the drain, which had not been considered before, increases, in addition to the influences of the parasitic capacitance between the drain and the source.