US Patent 10944365 Envelope tracking amplifier circuit

An envelope tracking (ET) amplifier circuit is provided. The ET amplifier circuit includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on an ET modulated voltage. The ET modulated voltage corresponds to a time-variant voltage envelope, which can be misaligned from a time-variant signal envelope of the RF signal due to inherent temporal delay in the ET amplifier circuit. As a result, the amplifier circuit may suffer degraded linearity performance. In this regard, a voltage processing circuit is provided in the ET amplifier circuit and configured to operate in a low-bandwidth mode and a high-bandwidth mode. In the high-bandwidth mode, the voltage processing circuit is configured to cause the ET modulated voltage to be modified to help improve delay tolerance of the ET amplifier circuit. As a result, it may be possible to reduce linearity degradation of the amplifier circuit to a predetermined threshold.