Extended operational bandwidth amplifiers with fractional instantaneous bandwidth feed forward correction
Apparatus and method for extended operational bandwidth amplifiers with fractional instantaneous bandwidth feed forward correction. In one embodiment, the method includes amplifying a radio frequency (RF) input signal to provide an amplified RF signal and introducing a first delay in the amplified RF signal. The method also includes receiving an error signal of the amplified RF signal and centering a correction bandwidth with respect to the amplified RF signal. The method also includes amplifying the error signal and combining the amplified RF signal and the amplified error signal to reduce an error in the amplified RF signal. The first delay is smaller than a second delay caused by the error path.
1. A power amplifier comprising:
a main amplifier amplifying a radio frequency (RF) input signal to provide an amplified radio frequency (RF) signal;
a feed forward correction loop coupled to the main amplifier for cancelling intermodulation distortion in the amplified RF signal, the feed forward correction loop including
a delay element in a main path of the feed forward correction loop,
an error amplifier in an error path, and
a composite phase shifter in the error path coupled to the error amplifier that centers a correction bandwidth with respect to the amplified RF signal,
wherein the delay element introduces a first delay in the amplified RF signal that is smaller than a second delay caused by the error path,
wherein the composite phase shifter includes:
a phase shifter in the error path of the feed forward correction loop; and
a phase extender in the error path coupled to the phase shifter that centers the phase shifter with respect to the amplified RF signal to center the correction bandwidth with respect to the amplified RF signal;
a memory storing a mapping between a plurality of frequency sub-bands and a plurality of phase settings; and
an electronic processor coupled to the memory and the feed forward correction loop and configured to
determine an operating frequency sub-band of the power amplifier;
determine a phase setting of the plurality of phase settings corresponding to the operating frequency sub-band; and
control the phase extender to apply the phase setting.
2. The power amplifier of claim 1 , wherein a composite phase shift range of the composite phase shifter is at least 540 degrees.
3. The power amplifier of claim 1 , wherein a composite phase shift range of the composite phase shifter is substantially greater than 540 degrees.
4. The power amplifier of claim 1 , wherein the first delay is less than 50% of the second delay.
5. The power amplifier of claim 1 , wherein the phase shifter includes quadrature reflection phase shifters and the phase extender includes delay line segments.
6. The power amplifier of claim 1 , wherein the electronic processor is further configured to communicate with a multi-carrier scheduler of a radio frequency (RF) transmitter to determine the operating frequency sub-band of the power amplifier.
7. A method for extending operation bandwidth of a power amplifier with fractional instantaneous bandwidth feed forward correction, the method comprising:
amplifying, using a main amplifier, a radio frequency (RF) input signal to provide an amplified RF signal;
introducing, using a delay element in a main path of a feed forward correction loop coupled to the main amplifier, a first delay in the amplified RF signal;
receiving, in an error path of the feed forward correction loop, an error signal of the amplified RF signal;
centering, using a composite phase shifter, a correction bandwidth with respect to the amplified RF signal, wherein the composite phase shifter includes a phase shifter and a phase extender;
phase shifting, using the phase shifter, a phase of the error signal, wherein centering the correction bandwidth includes centering, using the phase extender, the phase shifter with respect to the amplified RF signal;
amplifying, using an error amplifier, the error signal;
combining, using a coupler, the amplified RF signal and the amplified error signal to reduce an error in the amplified RF signal,
wherein the first delay is smaller than a second delay caused by the error path;
storing, using a memory, a mapping between a plurality of frequency sub-bands and a plurality of phase settings; and
determining, using an electronic processor coupled to the memory and the feed forward correction loop, an operating frequency sub-band of the power amplifier;
determining, using the electronic processor, a phase setting of the plurality of phase settings corresponding to the operating frequency sub-band in the mapping; and
controlling, using the electronic processor, the phase extender to apply the phase setting.
8. The method of claim 7 , wherein a composite phase shift range of the composite phase shifter is at least 540 degrees.
9. The method of claim 7 , wherein a composite phase shift range of the composite phase shifter is substantially greater than 540 degrees.
10. The method of claim 7 , wherein the first delay is less than 50% of the second delay.
11. The method of claim 7 , wherein the phase shifter includes quadrature reflection phase shifters and the phase extender includes delay line segments.
12. The method of claim 7 , further comprising communicating, using the electronic processor, with a multi-carrier scheduler of a radio frequency (RF) transmitter to determine the operating frequency sub-band of the power amplifier.
13. A power amplifier comprising:
a main amplifier amplifying a radio frequency (RF) input signal to provide an amplified radio frequency (RF) signal;
a feed forward correction loop coupled to the main amplifier for cancelling intermodulation distortion in the amplified RF signal, the feed forward correction loop including
a delay element in a main path of the feed forward correction loop,
an error amplifier in an error path, and
a composite phase shifter in the error path coupled to the error amplifier that centers a correction bandwidth with respect to the amplified RF signal,
wherein the delay element introduces a first delay in the amplified RF signal that is smaller than a second delay caused by the error path,
wherein the composite phase shifter includes:
a phase shifter in the error path of the feed forward correction loop; and
a phase extender in the error path coupled to the phase shifter that centers the phase shifter with respect to the amplified RF signal to center the correction bandwidth with respect to the amplified RF signal, wherein the phase shifter includes quadrature reflection phase shifters and the phase extender includes delay line segments.
14. A method for extending operation bandwidth of a power amplifier with fractional instantaneous bandwidth feed forward correction, the method comprising:
amplifying, using a main amplifier, a radio frequency (RF) input signal to provide an amplified RF signal;
introducing, using a delay element in a main path of a feed forward correction loop coupled to the main amplifier, a first delay in the amplified RF signal;
receiving, in an error path of the feed forward correction loop, an error signal of the amplified RF signal;
centering, using a composite phase shifter, a correction bandwidth with respect to the amplified RF signal, wherein the composite phase shifter includes a phase shifter and a phase extender;
phase shifting, using the phase shifter, a phase of the error signal, wherein centering the correction bandwidth includes centering, using the phase extender, the phase shifter with respect to the amplified RF signal, wherein the phase shifter includes quadrature reflection phase shifters and the phase extender includes delay line segments;
amplifying, using an error amplifier, the error signal; and
combining, using a coupler, the amplified RF signal and the amplified error signal to reduce an error in the amplified RF signal,
wherein the first delay is smaller than a second delay caused by the error path.