Combiner circuit for a class-E outphasing power amplifier
View Patent ↗Lumped-element based class-E Chireix combiners are disclosed that are equivalents of a quarter-wave transmission line combiner. The proposed class-E equivalent power amplifier circuits that are used can be derived from a parallel tuned class-E implementation. The proposed low-pass equivalents can behave similarly in terms of class-E performance, but absorb the 90 degree transmission line.
1. A combiner circuit for a class-E outphasing power amplifier comprising first and second branch amplifiers, the combiner circuit comprising:
a first input node, for receiving an output signal of the first branch amplifier;
a second input node, for receiving an output signal of the second branch amplifier;
an output node, for supplying a combined output signal to a load;
a first inductor connected in series at the first input node, the first inductor having an input terminal connected to the first input node and an output terminal;
a second inductor connected in series at the second input node, the second inductor having an input terminal connected to the second input node and an output terminal;
a compensation inductor connected in series with the first inductor and directly connected to the output node;
a compensation capacitor connected in series with the second inductor and directly connected to the output node;
a first capacitor, with a first terminal connected to the output terminal of the first inductor and a second terminal connected to ground; and
a second capacitor, with a first terminal connected the output terminal of the second inductor and a second terminal connected to ground;
wherein the second capacitor and the compensation capacitor are implemented as Metal-Insulator-Metal capacitors together on a single die, and wherein each of the capacitors and/or inductors is implemented as a lumped element component.
2. The combiner circuit of claim 1 , wherein:
the compensation inductor is directly connected to the output terminal of the first inductor; and
the compensation capacitor is directly connected to the output terminal of the second inductor.
3. The combiner circuit of claim 1 , further comprising a connection at the output terminal of the second inductor for connecting a DC-bias supply.
4. The combiner circuit of claim 1 , further comprising a matching circuit between the output node and the load.
5. A class-E outphasing power amplifier module, comprising:
the combiner circuit of claim 1 in combination with the first and second branch amplifiers of claim 1 , wherein the combiner circuit is arranged to combine the output signals of the first and second branch amplifiers.
6. A combiner circuit for a class-E outphasing power amplifier comprising first and second branch amplifiers, the combiner circuit comprising:
a first input node, for receiving an output signal of the first branch amplifier;
a second input node, for receiving an output signal of the second branch amplifier;
an output node, for supplying a combined output signal to a load;
a first inductor connected in series at the first input node, the first inductor having an input terminal connected to the first input node and an output terminal;
a second inductor connected in series at the second input node, the second inductor having an input terminal connected to the second input node and an output terminal;
a compensation inductor connected in shunt between the second input node and ground;
a further compensation inductor connected in series with the first inductor and directly connected to the output node;
a second capacitor, with a first terminal connected to the output terminal of the first inductor and a second terminal connected to ground; and
wherein the further compensation inductor is directly connected to the output terminal of the first inductor, and wherein each of the capacitors and/or inductors is implemented as a lumped element component.
7. The combiner circuit of claim 6 , further comprising a first capacitor connected in shunt between the output node and ground.
8. The combiner circuit of claim 6 , further comprising a compensation capacitor connected in shunt between the first input node and ground.
9. The combiner circuit of claim 6 , wherein:
one or more of the capacitors are implemented as Metal-Oxide-Semiconductor capacitors; and/or
one or more of the inductors are implemented as bond wires.