Doherty power amplifier with tunable impedance load

A radio frequency (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, wherein the main RF amplifier is coupled to the quadrature coupler, the peaking RF amplifier is coupled to the quadrature coupler, the quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the quadrature coupler, and wherein the peaking RF amplifier is configured to be deactivated while an RF signal is below a threshold level and is configured to be activated while the RF signal is above the threshold level and the main RF amplifier is configured to be activated while the RF signal is below the threshold level and above the threshold level;
• and
• a control circuit configured to dynamically detect RF power of the Doherty amplification circuit and tune the tunable impedance of the tunable impedance load dynamically as a function of the RF power of the Doherty amplification circuit such that a load impedance presented by the quadrature coupler to the main RF amplifier is decreased as the RF power of the Doherty amplification circuit is increased.

A radio frequency, (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, and wherein the quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the quadrature coupler;
• and
• a control circuit configured to dynamically detect RF power of the Doherty amplification circuit and dynamically tune the tunable impedance of the tunable impedance load as a function of the RF power, wherein the control circuit is further configured to receive a control input that indicates at least one operational frequency characteristic of the RF signal, and wherein the control circuit is configured to tune the tunable impedance of the tunable impedance load dynamically as the function is further of the at least one operational frequency characteristic indicated by the control input.

A radio frequency, (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, and wherein the quadrature coupler an output port configured to output the RF signal after amplification by the Doherty amplification circuit and an isolation port coupled to the tunable impedance load ;
• and
• a control circuit configured to dynamically detect RF power of the Doherty amplification circuit and dynamically tune the tunable impedance of the tunable impedance load as a function of the RF power, wherein the control circuit is coupled to the output port and is configured to detect the RF power in the Doherty amplification circuit by being configured to receive a feedback signal having a feedback signal level set in accordance with an RF signal level of the RF signal when the RF signal is output from the output port of the quadrature coupler.

A radio frequency, (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, wherein the main RF amplifier is coupled to the quadrature coupler and, the peaking RF amplifier is coupled to the quadrature coupler, the quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the quadrature coupler, and wherein the peaking RF amplifier is configured to receive a supply voltage such that a supply current is generated by the supply voltage;
• and
• a control circuit configured to dynamically detect RF power of the Doherty amplification circuit and dynamically tune the tunable impedance of the tunable impedance load as a function of the RF power, wherein the control circuit is coupled to the peaking RF amplifier and is configured to detect the RF power in the Doherty amplification circuit by being configured to receive a feedback signal having a feedback signal level set in accordance with a supply current level of the supply current.

A radio frequency ORFS amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler, a second quadrature coupler and a tunable impedance load configured to provide a tunable impedance, and wherein the quadrature coupler has an isolation port coupled to the tunable impedance load and the second quadrature coupler has an input port configured to receive the RF signal for the Doherty amplification circuit;
• and
• a control circuit configured to dynamically detect RF power of the Doherty amplification circuit and dynamically tune the tunable impedance of the tunable impedance load as a function of the RF power, wherein the control circuit is coupled to the input port and is configured to detect the RF power in the Doherty amplification circuit by being configured to receive a feedback signal having a feedback signal level set in accordance with an RF signal level of the RF signal at the input port of the second quadrature coupler.

A radio frequency (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, and wherein the quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the quadrature coupler;
• and
• a control circuit configured to receive a control input that indicates the RF power of the Doherty amplification circuit, store a look-up table, and tune the tunable impedance of the tunable impedance load dynamically as the function of the RF power of the Doherty amplification circuit indicated by the control input by being configured to implement the look-up table.

A radio frequency, (RF) amplification device comprising:

• a Doherty amplification circuit that functions as a Doherty amplifier and configured to amplify an RF signal, wherein the Doherty amplification circuit includes a main RF amplifier, a peaking RF amplifier, a quadrature coupler and a tunable impedance load configured to provide a tunable impedance, wherein the quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the quadrature coupler, and wherein the tunable impedance load comprises a plurality of selectable impedance branches including a plurality of switches;
• and
• a control circuit configured to tune the tunable impedance of the tunable impedance load dynamically as a function of the RF power of the Doherty amplification circuit by being configured to generate an impedance control output as the function of the RF power of the Doherty amplification circuit, wherein the tunable impedance load is configured to receive the impedance control output and operate the plurality of switches in accordance with the impedance control output.