Outphasing power combiner
The outphasing power combiner circuit includes a transformer having a primary coil coupled to a first power amplifier (PA) and a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil. The outphasing power combiner circuit further includes load impedance coupled between a median point of the primary coil and ground. The load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal in the primary coil with respect to the second phase of the second amplified constant-envelope signal in the primary coil, which results in improved power efficiency.
1. An power combiner circuit, comprising:
a transformer that includes a primary coil and a secondary coil, wherein the primary coil is coupled to a first power amplifier (PA) and a second PA, and
wherein the secondary coil is configured to supply a current to a differential antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil;
a ripple detector coupled to the primary coil, wherein the ripple detector is configured to detect at least one ripple in the current; and
a load impedance coupled between a median point of the primary coil and ground,
wherein the load impedance is adjusted to match the impedance of the differential antenna based on the detection of the at least one ripple in the current,
wherein the load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal in the primary coil with respect to the second phase of the second amplified constant-envelope signal in the primary coil, and
wherein the second direction of the first phase of the first amplified constant-envelope signal is different from the first direction of the first phase of the first amplified constant-envelope signal in the primary coil.
2. The power combiner circuit of claim 1 , wherein the primary coil of the transformer is coupled in parallel with the secondary coil of the transformer.
3. The power combiner circuit of claim 1 , wherein the first amplified constant-envelope signal is generated by the first PA based on a first constant-envelope signal, wherein the second amplified constant-envelope signal is generated by the second PA based on a second constant-envelope signal, and wherein the first constant-envelope signal is received by the first PA and the second constant-envelope signal is received by the second PA, from a signal decomposition block.
4. The power combiner circuit of claim 3 , wherein the first constant-envelope signal and the second constant-envelope signal are generated by the signal decomposition block based on a modulated input signal.
5. The power combiner circuit of claim 4 , wherein the modulated input signal is a variable amplitude modulated signal, wherein the first constant-envelope signal and the second constant-envelope signal are constant amplitude decomposed RF signals with corresponding phases in opposite direction.
6. The power combiner circuit of claim 1 , wherein the load impedance is adjustable, and wherein the load impedance is adjusted to match an impedance of the differential antenna based on detection of one or more ripples at the primary coil or in the current supplied to the differential antenna.
7. The power combiner circuit of claim 6 , further comprising a ripple detector coupled to the transformer to detect the one or more ripples at the primary coil or in the current supplied to the differential antenna.
8. The power combiner circuit of claim 7 , wherein the ripple detector is coupled in parallel to the secondary coil.
9. The power combiner circuit of claim 7 , wherein the ripple detector is coupled between ground and one of the primary coil or the secondary coil.
10. The power combiner circuit of claim 7 , wherein the ripple detector is coupled differentially between the primary coil and the secondary coil.
11. A radio frequency (RF) transmitter, comprising:
a first power amplifier (PA) and a second PA, wherein the first PA is configured to generate a first amplified constant-envelope signal based on a first constant-envelope signal, and wherein the second PA is configured to generate a second amplified constant-envelope signal based on a second constant-envelope signal;
a power combiner configured to combine the first amplified constant-envelope signal and the second amplified constant-envelope signal, the power combiner comprising:
a transformer that includes a primary coil and a secondary coil,
wherein the primary coil is coupled to the first PA and the second PA, and
wherein the secondary coil is configured to supply a current based on a first direction of a first phase of the first amplified constant-envelope signal in the primary coil with respect to a second phase of the second amplified constant-envelope signal in the primary coil;
a ripple detector coupled to the primary coil, wherein the ripple detector is configured to detect at least one ripple in the current; and
a load impedance coupled between a median point of the primary coil and ground,
wherein the load impedance is adjusted to match the impedance of a differential antenna based on the detection of the at least one ripple in the current,
wherein the load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal, and
wherein the second direction of the first phase of the first amplified constant-envelope signal is different from the first direction of the first phase of the first amplified constant-envelope signal in the primary coil; and
the differential antenna configured to receive the current supplied by the secondary coil of the transformer and transmit an output RF signal to a RF receiver, wherein the transmitted output RF signal corresponds to a combination of the first amplified constant-envelope signal and the second amplified constant-envelope signal.
12. The RF transmitter of claim 11 , further comprising a signal decomposition block configured to decompose a modulated input signal into the first constant-envelope signal and the second constant-envelope signal.
13. The RF transmitter of claim 12 , wherein the modulated input signal is a variable amplitude modulated signal, and wherein the first constant-envelope signal and the second constant-envelope signal are constant amplitude decomposed RF signals with corresponding phases in opposite direction.
14. The RF transmitter of claim 11 , wherein the primary coil of the transformer is coupled in parallel to the secondary coil of the transformer.
15. The RF transmitter of claim 11 , wherein the load impedance is adjustable, and wherein the load impedance is adjusted to match an impedance of the differential antenna based on detection of one or more ripples at the primary coil or in the current supplied to the differential antenna.
16. The RF transmitter of claim 15 , wherein the power combiner further comprises a ripple detector coupled to the transformer to detect the one or more ripples at the primary coil or in the current supplied to the differential antenna.
17. The RF transmitter of claim 16 , wherein the ripple detector is coupled in parallel to the secondary coil.
18. The RF transmitter of claim 16 , wherein the ripple detector is coupled between ground and one of the primary coil or the secondary coil.
19. The RF transmitter of claim 16 , wherein the ripple detector is coupled differentially between the primary coil and the secondary coil.
20. A power combiner circuit, comprising:
a transformer that includes a primary coil and a secondary coil, wherein the primary coil is coupled to a first power amplifier (PA) and a second PA, and
wherein the secondary coil is configured to supply a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil;
a load impedance coupled between a median point of the primary coil and ground,
wherein the load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal in the primary coil with respect to the second phase of the second amplified constant-envelope signal in the primary coil,
wherein the load impedance is adjustable, and
wherein the load impedance is adjusted to match an impedance of the antenna based on detection of one or more ripples at the primary coil or in the current supplied to the antenna.
21. A power combiner circuit, comprising:
a transformer that includes a primary coil and a secondary coil, wherein the primary coil is coupled to a first power amplifier (PA) and a second PA, and
wherein the secondary coil is configured to supply a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil;
a load impedance coupled between a median point of the primary coil and ground,
wherein the load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal in the primary coil with respect to the second phase of the second amplified constant-envelope signal in the primary coil; and
a ripple detector coupled to the transformer to detect one or more ripples at the primary coil or in the current supplied to the antenna, wherein the load impedance is adjusted until the ripple detector generates a direct current (DC) signal.
22. The power combiner circuit of claim 21 , wherein the ripple detector is coupled in parallel to the secondary coil.
23. The power combiner circuit of claim 21 , wherein the ripple detector is coupled between ground and one of the primary coil or the secondary coil.
24. The power combiner circuit of claim 21 , wherein the ripple detector is coupled differentially between the primary coil and the secondary coil.
25. A radio frequency (RF) transmitter, comprising:
a first power amplifier (PA) and a second PA, wherein the first PA is configured to generate a first amplified constant-envelope signal based on a first constant-envelope signal, and wherein the second PA is configured to generate a second amplified constant-envelope signal based on a second constant-envelope signal;
a power combiner configured to combine the first amplified constant-envelope signal and the second amplified constant-envelope signal, the power combiner comprising:
a transformer that includes a primary coil and a secondary coil, wherein the primary coil is coupled to the first PA and the second PA, and wherein the secondary coil is configured to supply a current based on a first direction of a first phase of the first amplified constant-envelope signal in the primary coil with respect to a second phase of the second amplified constant-envelope signal in the primary coil;
a load impedance coupled between a median point of the primary coil and ground, wherein the load impedance dissipates the current based on the first phase of the first amplified constant-envelope signal being same as the second phase of the second amplified constant-envelope signal; and
a ripple detector coupled to the transformer to detect one or more ripples at the primary coil or in the current supplied to an antenna; and
the antenna configured to receive the current supplied by the secondary coil of the transformer and transmit an output RF signal to a RF receiver, wherein the transmitted output RF signal corresponds to a combination of the first amplified constant-envelope signal and the second amplified constant-envelope signal.
26. The RF transmitter of claim 25 , wherein the ripple detector is coupled in parallel to the secondary coil.
27. The RF transmitter of claim 25 , wherein the ripple detector is coupled between ground and one of the primary coil or the secondary coil.
28. The RF transmitter of claim 25 , wherein the ripple detector is coupled differentially between the primary coil and the secondary coil.
29. A radio frequency (RF) transmitter, comprising:
a first power amplifier (PA) and a second PA, wherein the first PA is configured to generate a first amplified constant-envelope signal based on a first constant-envelope signal, and wherein the second PA is configured to generate a second amplified constant-envelope signal based on a second constant-envelope signal;
a power combiner configured to combine the first amplified constant-envelope signal and the second amplified constant-envelope signal, the power combiner comprising:
a transformer that includes a primary coil and a secondary coil, wherein the primary coil is coupled to the first PA and the second PA, and wherein the secondary coil is configured to supply a current based on a first direction of a first phase of the first amplified constant-envelope signal in the primary coil with respect to a second phase of the second amplified constant-envelope signal in the primary coil;
a load impedance coupled between a median point of the primary coil and ground, wherein the load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal,
wherein the load impedance is adjustable, and
wherein the load impedance is adjusted to match an impedance of an antenna based on detection of one or more ripples at the primary coil or in the current supplied to the antenna; and
the antenna configured to receive the current supplied by the secondary coil of the transformer and transmit an output RF signal to a RF receiver, wherein the transmitted output RF signal corresponds to a combination of the first amplified constant-envelope signal and the second amplified constant-envelope signal.