Butler-Doherty power amplifier

Abstract

A Butler Doherty power amplifier suitable for wireless communications systems comprising of a Butler matrix network and a Doherty power amplifying stage, is disclosed. The Butler matrix network which consists of an input processing stage comprising a first hybrid or coupler, a first phase difference setting stage, a second hybrid or coupler, and a second phase difference setting stage, a plurality of power amplifier driver stages, a third hybrid or coupler and a plurality of phase setting stages is capable of accepting an RF input signal, maintaining equal power sharing in a plurality of power amplifier driver stages and supplying the Doherty power amplifying stage with independently controlled drive signals. The Doherty power amplifying stage which consists of a carrier power amplifier with an associated matching network, a peaking power amplifier with an associated matching network, a plurality of phase setting stages and Doherty combining network, is capable of accepting drive signals from the Butler splitting stage, amplifying these signals with high efficiency under Doherty operation and providing the resultant signal to an output load. The Butler matrix network facilitates the optimal distribution of power to the constituent stages of the Doherty amplifier such that optimum linearity and efficiency is maintained for high peak to average ratio RF signals.

Description

technical field [0001] The invention relates to the technical field of power amplifiers, in particular to a Doherty high-efficiency power amplifier used in radio frequency and microwave band wireless communication applications. Background technique [0002] The current industry need for highly efficient linear radio frequency (RF) power amplifiers is well known. This is because there are many applications that require such an amplifier. Typically, these amplifiers are used in portable transmitters such as mobile phones and wireless base station applications. [0003] In cell sites, satellite communications, and other communications broadcast systems, a power amplifier (PA) can simultaneously amplify multiple radio frequency (RF) carriers that can scale to large bandwidths. Due to the large peak-to-average ratio (PAR) of a multi-carrier signal as the sum of multiple independent RF carriers, the amplitude distribution of the signal is also similar to the Rayleigh distributio...

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Problems solved by technology

[0016] However, Gans et al. used the Butler matrix as a method to detect nonlinearities, and did not propose to use it to distribute the power of the Doherty power amplifier and allow the input power of the carrier amplifier and the peaking amplifier to be adjusted separately.

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