High-efficiency modulating RF amplifier
View Patent ↗The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation. Amplitude modulation may be achieved by directly or effectively varying the operating voltage on the power amplifier while simultaneously achieving high efficiency in the conversion of primary DC power to the amplitude modulated output signal. High efficiency is enhanced by allowing the switch-mode DC-to-DC converter to also vary its output voltage such that the voltage drop across the linear regulator is kept at a low and relatively constant level. Time-division multiple access (TDMA) bursting capability may be combined with efficient amplitude modulation, with control of these functions being combined. In addition, the variation of average output power level in accordance with commands from a communications system may also be combined within the same structure.
1. An amplifier apparatus for use in a polar modulation structure, said amplifier apparatus comprising:
a power control circuit for directly receiving a magnitude signal, a power supply signal and a control signal defining at least a power level and burst information, and producing a drive signal in accordance with the control signal; and
an amplifier for receiving an RF input signal and the drive signal, and amplifying the RF input signal using the drive signal to produce an RF output signal.
2. The amplifier apparatus according to claim 1 , wherein said amplifier is a non-liner amplifier or a switch-mode non-linear amplifier.
3. An amplifier apparatus for use in a polar modulation structure according to claim 1 , wherein said control signal is provided to said power control circuit without utilizing any feedback of said RF output signal.
4. An amplifier apparatus for use in a polar modulation structure according to claim 1 , wherein said power control circuit provides for adjustment of the output level of said RF output signal without utilizing any feedback of said RF output signal.
5. A wireless communications device comprising an amplifier apparatus for use in a polar modulation structure, said amplifier apparatus comprising:
a power control circuit operable to produce a drive signal using a magnitude signal, a power supply signal, and a control signal defining at least a power level and burst information; and
an amplifier for receiving an RF input signal and the drive signal produced by said power control circuit, said amplifier operable to amplify the RF input signal using the drive signal to produce an RF output signal.
6. The wireless communications device according to claim 5 , wherein said amplifier is a non-linear amplifier or a switch-mode non-linear amplifier.
7. An amplifier apparatus for use in a polar modulation structure according to claim 1 , wherein said power control circuit comprises a first converter for performing gross adjustment of the signal level of said power supply signal; and a second converter for receiving an output signal from said first converter and for performing fine adjustment of said signal level of said output signal of said first converter.
8. An amplifier apparatus for use in a polar modulation structure according to claim 7 , wherein said first converter comprises a switch-mode converter, and said second converter comprises a linear regulator.
9. An amplifier apparatus for use in a polar modulation structure, said amplifier apparatus comprising:
a power control circuit for directly receiving a magnitude signal, a power supply signal and a control signal defining at least a power level, and producing a drive signal in accordance with the control signal; and
an amplifier for receiving an RF input signal and said drive signal, and amplifying said RF input signal using said drive signal to produce an RF output signal,
wherein said power control circuit includes a first converter for performing gross adjustment of a signal level of said power supply signal; and a second converter for receiving an output signal from said first converter and for performing fine adjustment of a signal level of said output signal of said first converter.
10. The amplifier apparatus according to claim 9 , wherein said amplifier is a non-linear amplifier or a switch-mode non-linear amplifier.
11. The amplifier apparatus for use in a polar modulation structure according to claim 9 , wherein said first converter includes a switch-mode converter, and said second converter includes a linear regulator.
12. The amplifier apparatus for use in a polar modulation structure according to claim 9 , wherein said power control circuit provides for adjustment of said output level of said RF output signal without utilizing any feedback of an RF output signal.
13. A wireless communications device comprising an amplifier apparatus for use in a polar modulation structure, said amplifier apparatus comprising:
a power control circuit operable to produce a drive signal using a magnitude signal, a power supply signal, and a control signal defining at least a power level; and
an amplifier for receiving an RF input signal and said drive signal produced by said power control circuit, said amplifier being operable to amplify said RF input signal using said drive signal to produce an RF output signal,
wherein said power control circuit includes a first converter for performing gross adjustment of a signal level of said power supply signal; and a second converter for receiving an output signal from said first converter and for performing fine adjustment of a signal level of said output signal of said first converter.
14. The wireless communications device according to claim 13 , wherein said amplifier is a non-linear amplifier or a switch-mode non-linear amplifier.
15. The wireless communications device according to claim 13 , wherein said first converter includes a switch-mode converter, and said second converter includes a linear regulator.
16. The wireless communications device according to claim 13 , wherein said power control circuit provides for adjustment of said output level of said RF output signal without utilizing any feedback of an RF output signal.