Qualcomm Incorporated/Seyfarth Shaw LLP
Source follower based envelope tracking for power amplifier biasing
A power amplifier bias circuit with embedded envelope detection includes a bias circuit stage coupled to an envelope detector circuit to increases a bias provided to a power amplifier as a function of an incoming envelope signal. The envelope detector circuit includes a first source/emitter follower transistor, a current source, and a filter to generate a baseband envelope signal. The current source is coupled to an output node of the first source/emitter follower transistor and the filter is also coupled to the output node of the first source/emitter follower transistor. The bias circuit stage includes one or more replica transistors that replicate transistors of the power amplifier or power amplifier core stage, an envelope detector replica transistor and a replica of the current source of the envelope detector circuit.
QUALCOMM Incorporated
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Jiang Jose Jeremy
Chen Cabanillas Goldblatt