RF-input / RF-output outphasing amplifier
A power combining and outphasing system and related techniques for simultaneously providing both wide-bandwidth linear amplification and high average efficiency is described. Providing linear amplification encompasses the ability to dynamically control an RF output power level over a wide range while still operating over a wide frequency bandwidth. The system and techniques described herein also operate to maintain high efficiency across a wide range of output power levels, such that a high average efficiency can be achieved for highly modulated output waveforms.
1. An outphasing amplification system comprising:
a radio-frequency signal decomposition network (RFSDN) having:
an input port coupled to receive an RF input signal;
N branch signal paths, where N is an integer greater than or equal to two;
at least one nonlinear component, each of the at least one nonlinear components coupled to a respective one of the branch signal paths; and
N output ports, each of the output ports coupled to a respective one of the branch signal paths; and
N branch amplifiers, each of the branch amplifiers having an input port coupled to receive a respective one of the RFSDN output ports and having an output port; and
a combiner network having N inputs ports, each of the combiner network inputs port coupled to an respective one of the branch amplifier output ports.
2. The outphasing amplification system of claim 1 wherein the at least one nonlinear component is provided as a one-port device having a nonlinear impedance characteristic to radio-frequency (RF) signals provided thereto.
3. The outphasing amplification system of claim 1 wherein N=2 M , M is an integer greater than or equal to one, and wherein the RFSDN has at least N nonlinear components.
4. The outphasing amplification system of claim 1 wherein the at least one nonlinear component is configured to provide phase modulation at the output ports in response to amplitude modulation at the input port.
5. The outphasing amplification system of claim 1 wherein the at least one nonlinear component is configured such that, if an amplitude of the RF input signal is below a given threshold, relative phases at the output ports to remain fixed.
6. The outphasing amplification system of claim 1 wherein the RFSDN further comprises a resistance compression network (RCN).
7. The outphasing amplification system of claim 6 wherein the RFSDN has at least N nonlinear components and wherein the RCN is provided as an N-way RCN coupled to the at least N nonlinear components.
8. The outphasing amplification system of claim 1 wherein the RFSDN is configured to perform amplitude modulation for operation below a nominal outphasing range.
9. The outphasing amplification system of claim 1 wherein the RFSDN and the combiner network have a substantially inverse structural relationship.
10. The outphasing amplification system of claim 1 further comprising N driver amplifiers, each of the driver amplifiers having an input port coupled a to receive a respective one of the RFSDN output ports and having an output port coupled to a respective one of the branch amplifiers.
11. The outphasing amplification system of claim 1 wherein the at least one nonlinear component comprises an input node, a parallel resistor coupled between the input node and a ground, and two opposing diodes coupled between the input node and the ground.
12. An outphasing amplification system comprising:
a radio-frequency signal decomposition network (RFSDN) having an input port, N branch signal paths, and N output ports, wherein in response to amplitude modulation of a signal at the input port, said RFSDN causes relative phase modulation in signals appearing at each of the N output ports, where N is an integer greater than or equal to two;
N branch amplifiers, each of the branch amplifiers having an input port coupled to a respective one of the N RFSDN output ports and each one of the branch amplifiers having a branch amplifier output port with each output port of the N branch amplifiers coupled to a respective one of the branch signal paths;
a combiner network having N inputs ports, each of the combiner network inputs port coupled to a respective one of the N branch amplifier output ports; and
at least one nonlinear component, each of the at least one nonlinear components coupled to a respective one of the branch signal paths.
13. The outphasing amplification system of claim 12 wherein, in response to a signal at the RFSDN input port having an amplitude below a predetermined amplitude level, relative phases at the N RFSDN output ports remain fixed.
14. The outphasing amplification system of claim 12 wherein the at least one nonlinear component is provided as a one-port device.
15. The outphasing amplification system of claim 12 wherein N=2 M , M is an integer greater than or equal to one, and wherein the RFSDN has at least N nonlinear components.
16. The outphasing amplification system of claim 12 wherein the at least one nonlinear component comprises an input node, a resistor coupled between the input node and a ground, and two opposing diodes coupled between the input node and the ground.
17. The outphasing amplification system of claim 12 wherein the at least one nonlinear component is provided as a two-port device.
18. An outphasing amplification system comprising a radio-frequency signal decomposition network (RFSDN) having an input port and N output ports, wherein in response to amplitude modulation of a signal at the input port, said RFSDN causes relative phase modulation in signals appearing at each of the N output ports, where N is an integer greater than or equal to two; and wherein the RFSDN further comprises a resistance compression network (RCN).
19. The outphasing amplification system of claim 18 wherein the RFSDN has N nonlinear components and wherein the RCN is provided as an N-way RCN coupled to N nonlinear components.