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1. (WO1998051007) METHOD AND APPARATUS FOR EFFICIENT SIGNAL POWER AMPLIFICATION
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CLAIMS

1. An apparatus comprising:
a power combiner responsive to first and second input signals to generate a first output signal representing a sum of the first and second input signals, and a second output signal representing a difference between the first and second input signals; and a power recovery circuit coupled to one of the first and second output signals.

2. The apparatus of claim 1, wherein:
the combiner includes first, second, third, and fourth ports;
the first and second ports is coupled to the first and second input signals, respectively;
the third and fourth ports provides the first and second output signals respectively;
the first output signal is generated from a portion of the first input signal and a portion of the second input signal, which portions have a first phase difference therebetween;
the second output signal being generated from a portion of the first input signal and a portion of the second input signal, which portions have a second phase difference therebetween that is substantially equal to the first phase difference plus 180 degrees.

3. The apparatus of claim 2, further comprising:
a first impedance transformer coupled between the first and third ports;
a second impedance transformer coupled between the second and third ports;
a third impedance transformer coupled between the second and
fourth ports;
a fourth impedance transformer coupled between fourth and first ports;
wherein the first, second, and fourth impedance transformers
each has a phase shift of substantially 90 degrees; and
wherein the third impedance transformer has a phase shift of
substantially 270 degrees.

4. A method of efficient power amplification comprising the steps of:
combining two radio frequency input signals to generate a
amplitude modulated signal and a power recovery signal; and storing energy derived from the power recovery signal for reuse as a power source.

5. The method of claim 4, wherein the two input signals have constant amplitude and a varying phase relationship with respect to each other.

6. The method of claim 5, wherein the step of combining two radio frequency input signals includes the steps of:
providing a phase shift between the two input signals by a first
amount, relative to each other, to generate the amplitude
modulated signal; and
providing a phase shift between the two input signals by the first amount, plus an additional phase shift of substantially 180
degrees relative to each other in order to generate the power
recovery signal.

7. A method of recovering radio frequency energy in a transmitter, comprising the steps of:
generating first and second amplified radio frequency signals
having a particular varying phase relationship, and having
substantially constant amplitudes;
combining the first and second amplified radio frequency signals
to generate a amplitude modulated radio frequency signal and a power recovery radio frequency signal; and
converting the power recovery radio frequency signal into a direct current power signal.

8. The method of claim 7, further including the step of recharging an energy cell using the direct current power signal.

9. A communication device comprising:
a transmitter having a linear amplifier, the linear amplifier
comprising substantially non-linear components; and
a power recovery circuit coupled to the linear amplifier to store
unused energy from the transmitter.

10. The communication device of claim 9, wherein the non-linear circuits include at least two amplifiers operating in a non-linear class of operation.