Radio frequency power amplifier with adjacent channel leakage correction circuit
A radio frequency (RF) system is described for use in a wireless communication device. The RF system may contain power amplifiers, additional circuitry and components (e.g., gain controllers, phase shifters), and/or antennas. The RF system is described in a variety of different configurations with its functionality divided up over several single chip circuits. Using the single chip circuits simplifies assembly, reduces size, and allows for high speed RF performance demanded by fixed and mobile wireless standards. The system may use a first amplifier circuit combined with an adjacent channel leakage correction circuit so that the output of the first amplifier has the signal leakage substantially cancelled.
1. A circuit comprising:
a power divider configured to divide an input signal into a first divided signal and a second divided signal, wherein the first divided signal is coupled to a first power amplifier and the second divided signal is coupled to the adjacent channel leakage correction circuit;
wherein the adjacent channel leakage correction circuit comprises:
a phase shifter and attenuation circuit to change the phase of the second divided signal to have the opposite phase of the first divided signal and to lower the signal power level of the second divided signal;
a second power amplifier coupled to the phase shifter and attenuation circuit configured to amplify and adjust the output of the phase shifter and attenuation circuit, wherein the second power amplifier has a lower output than the first power amplifier;
a power combining circuit coupled to the output of the first power amplifier and second power amplifier and configured to substantially remove leakage from the first power amplifier output signal by combining the output signal of the first power amplifier with the second power amplifier output signal to produce a power combining circuit output signal; and
wherein a biasing control circuit is connected to the second power amplifier to set the linearity of the power combining circuit output signal.
2. The circuit of claim 1 , wherein the adjacent channel leakage correction circuit further comprises:
a biasing control circuit connected to the second power amplifier and configured to produce high adjacent channel leakage in the second power amplifier output signal to cancel leakage of the first power amplifier output signal.
3. The circuit of claim 1 , wherein the adjacent channel leakage correction circuit further comprises:
a gain adjustment circuit connected to the second amplifier and configured to compensate the gain expansion and compression between the first power amplifier and the second power amplifier.
4. The circuit of claim 1 , wherein the adjacent channel leakage correction circuit further comprises:
a phase adjustment circuit configured to control variations in the phase of the amplified signal over a range of the output power.
5. The circuit of claim 1 wherein the first power amplifier and second power amplifier are arranged in parallel.
6. The circuit of claim 1 , wherein the first and second power amplifiers, biasing circuit, phase adjustment circuit and gain adjustment circuit are made using at least one of the group consisting of: GaAs, GaN, CMOS, SiGe, and InP.
7. The circuit of claim 1 , wherein the frequency of the power combining circuit output signal is in the range of approximately 3.3 to 3.8 GHz.
8. The circuit of claim 1 , wherein the frequency of the power combining circuit output signal is in the range of a group consisting of: 2.3 to 2.7 GHz, 3.3 to 3.8 GHz, 5.0 to 6.0 GHz, 23-25 GHz, the 28 GHz band which is in a range of 27.5 to 28.35 GHz, the 37 GHz band which is in the range of 37 to 38.6 GHz; the 39 GHz Band which is in the range of 38.6 to 40 GHz, and the 64 to 71 GHz band.
9. The circuit of claim 1 wherein the power divider is a power coupler.
10. The circuit of claim 1 , wherein the power combining circuit is a power coupler.
11. The circuit of claim 1 further comprising a feedback loop between the output of the power combining circuit and the adjacent channel leakage circuit and a power, gain and phase sensing circuit to adjust operation of the second power amplifier.
12. The circuit of claim 1 , wherein the adjacent channel leakage circuit further comprises machine learning software to adjust operation of the second power amplifier.
13. The circuit of claim 1 , wherein the power combining circuit output signal will have decibels relative to transmission signal in the transmission channel (dBc) in the range of approximately −40 dBc to −70 dBc.
14. The circuit of claim 1 , wherein the power levels of the first divided signal and the second divided signal are approximately equal.
15. The circuit of claim 1 , wherein the first divided signal is in a range of approximately 90% to 99.9% of the power of the RF input signal.
16. A method comprising:
dividing a radio frequency input signal into a first divided signal and a second divided signal at a power divider;
forwarding the first divided signal to a first amplifier and outputting a first amplifier output signal;
forwarding the second divided signal to a phase shifter and attenuation circuit to shift the phase of the second divided signal to be approximately opposite to that of the first amplifier output signal and lower the signal power level of the second divided signal;
passing the second divided signal to a second power amplifier to amplify and adjust the second divided signal to output a second power amplifier output signal, wherein the second power amplifier has a lower output than the first power amplifier; and
combining the first power amplifier output signal and the second power amplifier output signal in a power combining circuit to substantially remove leakage from the first power amplifier output in a power combining circuit output signal.
17. The method of claim 16 , further comprising:
adjusting the second amplifier with a biasing control circuit to produce high adjacent channel leakage in the second power amplifier output signal to cancel leakage of the first power amplifier output signal.
18. The method of claim 16 , further comprising:
measuring the output of the power combining circuit and feeding back this measurement to a feedback control circuit coupled to plurality of circuits capable of adjusting the second power amplifier.
19. A circuit comprising:
a power divider configured to divide an input signal into a first divided signal and a second divided signal, wherein the first divided signal is coupled to a first power amplifier and the second divided signal is less than 10% of the input signal and coupled to the adjacent channel leakage correction circuit;
wherein the adjacent channel leakage correction circuit comprises:
a phase shifter and attenuation circuit to change the phase of the second divided signal to have the opposite phase of the first divided signal and to lower the signal power level of the second divided signal;
a second power amplifier coupled to the phase shifter and attenuation circuit configured to amplify and adjust the output of the phase shifter and attenuation circuit wherein the output of the second amplifier is the opposite of the adjacent channel leakage signal output from the first amplifier, wherein the second power amplifier has a lower output than the first power amplifier;
a power combining circuit coupled to the output of the first power amplifier and second power amplifier and configured to substantially remove leakage from the first power amplifier output signal by combining the output signal of the first power amplifier with the second power amplifier output signal to produce a power combining circuit output signal.