Patent ID: 9397617
Filing Date: 2016-07-19
CPC Classification: H03F

Claim Text:
1. A radio frequency (RF) amplification device comprising a Doherty amplification circuit configured to amplify an RF signal, wherein the Doherty amplification circuit comprises: a main carrier RF amplifier; a peaking RF amplifier configured to be deactivated while the RF signal is below a threshold level and configured to be activated while the RF signal is above the threshold level; a periodic quadrature coupler having an output port configured to output the RF signal after amplification by the Doherty amplification circuit, wherein the periodic quadrature coupler is configured to combine a first RF split signal from the main carrier RF amplifier and a second RF split signal from the peaking RF amplifier into the RF signal such that the RF signal is output from the output port after amplification by the Doherty amplification circuit while the peaking RF amplifier is activated; a tunable impedance load configured to provide a tunable impedance, and wherein the periodic quadrature coupler has an isolation port and the tunable impedance load is coupled to the isolation port of the periodic quadrature coupler; and a control circuit configured to tune the tunable impedance of the tunable impedance load dynamically as a function of RF power to employ Doherty amplification operation, wherein the tunable impedance load is increased as the RF power is backed off to employ Doherty amplification operation.