Transmitter and method for RF power amplifier having a bandwidth controlled, detroughed envelope tracking signal

摘要

A transmitter (70) generates a time-varying, detroughed, biasing signal (154) for an RF power amplifier (10) so that the RF power amplifier (10) is biased in accordance with an envelope tracking scheme. A trough-filling section (94) is responsive to an envelope tracking signal (86), which in turn is responsive to a magnitude signal (90) extracted from a complex baseband communication signal (76). The trough-filing section (94) includes a limiting stage (108) that forms a raw troughing signal (110) which expands the bandwidth of the envelope tracking signal (86). A filtering stage (116) reduces the bandwidth of the raw troughing signal (110) to form a trough-filling signal (122) that is combined back into the envelope tracking signal (86) using a linear process that maintains the bandwidth of the envelope tracking signal (86).

主权项

1. A method of operating an RF transmitter utilizing a linear, envelope-tracking, RF power amplifier having an output which receives a biasing signal and having an input, said method comprising:
forming a deeper-trough envelope tracking signal for a baseband communication signal, said deeper-trough envelope tracking signal exhibiting peaks and troughs wherein at least a portion of said troughs are deeper than corresponding troughs in a shallower-trough envelope tracking signal; forming a trough-filling signal from said deeper-trough envelope tracking signal, said trough-filling signal being configured to isolate said portion of said troughs; combining said trough-filling signal with said deeper-trough envelope tracking signal to detrough said deeper-trough envelope tracking signal and form said shallower-trough envelope tracking signal; biasing said output of said RF power amplifier in response to said shallower-trough envelope tracking signal; and driving said input of said RF power amplifier with an RF communication signal formed in response to said baseband communication signal.