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 first amplifier connected to the circuit input 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 connected to the circuit input and to a second bias input, the first and second bias inputs being set such that, when a voltage of an input signal to the circuit input is at a first level, the first amplifier is on and the second amplifier is off and, when a voltage of the input signal is at a second level, the first amplifier is saturated and the second amplifier is on; 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 further comprising a driver amplifier defined by a driver input and a driver output, the driver input being connected to the circuit input, and the driver output being connected to the first amplifier and the second 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 B amplifier.
4. 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.
5. The radio frequency power combining amplifier circuit of claim 1 wherein the first bias input is independent of the second bias input.
6. The radio frequency power combining amplifier circuit of claim 1 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.
7. 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.
8. 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.
9. A radio frequency power combining amplifier circuit with a circuit input and a circuit output, comprising:
a first amplifier connected to the circuit input and to a first bias input, 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 connected to the circuit input and to a second bias input, the second amplifier being defined by a gain expansion dominance operating region corresponding to a second voltage level of the input signal, the first and second bias inputs being set such that, when the input signal is at the first voltage level, the first amplifier is on and the second amplifier is off and, when the input signal is at the second voltage level, the first amplifier is saturated and the second amplifier is on; and
a second output matching network connected to an output of the second amplifier and to the circuit output.
10. The radio frequency power combining amplifier circuit of claim 9 wherein the first amplifier is a class A amplifier, and the second amplifier is a class B amplifier.
11. The radio frequency power combining amplifier circuit of claim 9 wherein the first amplifier is a class A amplifier and the second amplifier is a class AB amplifier.
12. The radio frequency power combining amplifier circuit of claim 9 wherein the first bias input is independent of the second bias input.
13. The radio frequency power combining amplifier circuit of claim 9 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.
14. The radio frequency power combining amplifier circuit of claim 9 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.
15. A radio frequency integrated circuit with an input and an output, comprising:
a semiconductor substrate;
a first amplifier fabricated on the semiconductor substrate and connected to the input and to a first bias input, 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 connected to the input and to a second bias input, 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 first and second bias inputs being set such that, when the radio frequency signal applied to the input is at the first voltage level, the first amplifier is on and the second amplifier is off and, when the radio signal applied to the input is at the second voltage level, the first amplifier is saturated and the second amplifier is on; and
a second output matching network fabricated on the semiconductor substrate and connected to the second amplifier and to the output.
16. The radio frequency integrated circuit of claim 15 wherein the semiconductor substrate is a complementary metal-oxide type.
17. The radio frequency integrated circuit of claim 15 wherein the first amplifier is a class A amplifier, and the second amplifier is a class B amplifier.
18. The radio frequency integrated circuit of claim 15 wherein the first amplifier is a class A amplifier and the second amplifier is a class AB amplifier.
19. The radio frequency integrated circuit of claim 15 wherein the first bias input is independent of the second bias input.
20. The radio frequency integrated circuit of claim 15 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.