Open loop digital PWM envelope tracking system with dynamic boosting

摘要

A system, apparatus and method is described for dynamically boosting (increasing) the power supply voltage to an envelope tracking (ET) modulator within a transmitter system when the target/desired power amplifier voltage supply is above a predetermined threshold (e.g., equal to the available power supply of the system, such as a battery). By boosting the power input supply to the ET modulator, the modulated power supply provided to the power amplifier (PA) is also increased. This reduces or eliminates clipping that normally occurs when the target/desired PA supply voltage is greater than the available power supply voltage and reduces distortion in the transmitted signal.

主权项

1. A transmitter comprising:
an envelope generator configured to receive a data signal to be transmitted and generate an envelope signal based on the received data signal; a pulse width modulation (PWM) generator coupled to the envelope generator and configured to output a PWM signal, the PWM generator comprising a sense circuit and a multiplexer; and an envelope tracking (ET) modulator coupled to the PWM generator and configured to receive the PWM signal and output a power amplifier (PA) switching supply source, wherein the ET modulator is further configured to receive a one of a first supply voltage or a second supply voltage in response to an ET modulator boost enable signal, wherein the second supply voltage is greater than the first supply voltage; wherein:
the sense circuit is configured to:
sense the first supply voltage, andgenerate a sense signal representative of the first supply voltage; andthe multiplexer is configured to:
receive the sense signal,receive a boost signal representative of the second supply voltage, andselectively output the sense signal or the boost signal in response to the ET modulator boost enable signal.