Voltage mode power combiner for radio frequency linear power amplifier
A radio frequency (RF) power combining amplifier circuit has a circuit input and a circuit output. A first amplifier is connected to the circuit input and to a first bias input. A first output matching network is connected to an output of the first amplifier and to the circuit output. A second amplifier is connected to the circuit input and to a second bias input. A second output matching network is connected to an output of the second amplifier, and to the circuit output. A voltage level of an input signal applied to the circuit input, together with the respective first bias input and the second bias input, selectively activates the first amplifier and the second amplifier.
1. A radio frequency power combining amplifier circuit with a circuit input and a circuit output, comprising:
a driver amplifier defined by a driver input and a driver output, the driver input being connected to the circuit input;
a first amplifier directly connected to the driver output and to a first bias input;
a first output matching network connected to an output of the first amplifier and to the circuit output, the first output matching network and the first amplifier being optimized for small signal linearity;
a second amplifier directly connected to the driver output and to a second bias input, inputs to the first bias input and the second bias input, and a voltage level of an input signal to the circuit input selectively activating the first amplifier and the second amplifier, the input signal as applied to the first amplifier and the second amplifier being in-phase relative to each other; and
a second output matching network connected to an output of the second amplifier and to the circuit output, the second output matching network and the second amplifier being optimized for maximum linear output power.
2. The radio frequency power combining amplifier circuit of claim 1 wherein the first amplifier is a class A amplifier, and the second amplifier is a class B amplifier.
3. The radio frequency power combining amplifier circuit of claim 1 wherein the first amplifier is a class A amplifier and the second amplifier is a class AB amplifier.
4. The radio frequency power combining amplifier circuit of claim 1 wherein the first bias input is independent of the second bias input.
5. The radio frequency power combining amplifier circuit of claim 4 further comprising a first capacitor connected to an input to the first amplifier and a second capacitor connected to an input to the second amplifier.
6. The radio frequency power combining amplifier circuit of claim 4 wherein a voltage level of the first bias input and a voltage level of the second bias input are different.
7. The radio frequency power combining amplifier circuit of claim 1 wherein the second amplifier is deactivated with the input signal being under a predefined voltage threshold.
8. The radio frequency power combining amplifier of claim 1 wherein the first amplifier is saturated with the input signal being over a predefined voltage threshold.
9. The radio frequency power combining amplifier circuit of claim 1 wherein the first amplifier, the first output matching network, the second amplifier, and the second output matching network are fabricated on a complementary metal-oxide semiconductor integrated circuit.
10. The radio frequency power combining amplifier circuit of claim 1 wherein each of the first output matching network and the second output matching network includes a harmonic blocking circuit.
11. A radio frequency power combining amplifier circuit with a circuit input and a circuit output, comprising:
a driver amplifier defined by a driver input and a driver output, the driver input being connected to the circuit input;
a first amplifier directly connected to the driver output, the first amplifier being defined by a small signal linearity dominance operating region corresponding to a first voltage level of an input signal;
a first output matching network connected to an output of the first amplifier and to the circuit output;
a second amplifier directly connected to the driver output, the second amplifier being defined by a gain expansion dominance operating region corresponding to a second voltage level of the input signal, the input signal as applied to the first amplifier and the second amplifier being in-phase relative to each other; and
a second output matching network connected to an output of the second amplifier and to the circuit output.
12. The radio frequency power combining amplifier circuit of claim 11 wherein the first amplifier includes a first bias input and the second amplifier includes a second bias input.
13. The radio frequency power combining amplifier circuit of claim 12 wherein inputs to the first bias input and the second bias input, together with the input signal, selectively activates the first amplifier and the second amplifier.
14. The radio frequency power combining amplifier circuit of claim 11 wherein the first amplifier is a class A amplifier, and the second amplifier is a class B amplifier.
15. The radio frequency power combining amplifier circuit of claim 11 wherein the first amplifier is a class A amplifier and the second amplifier is a class AB amplifier.
16. The radio frequency power combining amplifier circuit of claim 11 wherein the first bias input is independent of the second bias input.
17. The radio frequency power combining amplifier circuit of claim 16 further comprising a first capacitor connected to an input to the first amplifier and a second capacitor connected to an input to the second amplifier.
18. The radio frequency power combining amplifier circuit of claim 17 wherein a voltage level of the first bias input and a voltage level of the second bias input are different.
19. A radio frequency integrated circuit with a circuit input and a circuit output, comprising:
a semiconductor substrate;
a driver amplifier fabricated on the semiconductor substrate and defined by a driver input and a driver output, the driver input being connected to the circuit input;
a first amplifier fabricated on the semiconductor substrate and directly connected to the driver output, the first amplifier being defined by a small signal linearity dominance operating region corresponding a first voltage level of a radio frequency signal applied to the input;
a first output matching network fabricated on the semiconductor substrate and connected to the first amplifier and to the output;
a second amplifier fabricated on the semiconductor substrate and directly connected to the driver output, the second amplifier being defined by a gain expansion dominance operating region corresponding to a second voltage level of the radio frequency signal applied to the input, the input signal as applied to the first amplifier and the second amplifier being in-phase relative to each other; and
a second output matching network fabricated on the semiconductor substrate and connected to the second amplifier and to the output.
20. The radio frequency integrated circuit of claim 19 wherein the semiconductor substrate is a complementary metal-oxide type.