A doherty power amplifier and its implementation method based on improved load modulation network to expand bandwidth

Abstract

The present invention provides a Doherty power amplifier based on an improved load modulation network to expand the bandwidth and its implementation method. The equalized Wilkinson power divider is used to divide the input power into equal parts and output them to the main power amplifier circuit and the auxiliary power amplifier circuit respectively. The output terminal of the main power amplifier circuit is connected to the 70.7 ohm quarter-wavelength impedance converter T1, the output terminal of the auxiliary power amplifier circuit is connected to the 70.7 ohm quarter-wavelength impedance converter T3, and the power is output to the load after the circuit is combined. The output terminal of the No. 1 channel is paralleled with a quarter-wavelength short-terminal T2. Compared with the prior art, the present invention reduces the impedance conversion ratio of the load modulation network by improving the load modulation network of the traditional Doherty power amplifier and paralleling the quarter-wavelength short wiring scheme at the output end, effectively suppressing the load impedance from changing with the frequency The drift greatly widens the operating bandwidth of the Doherty power amplifier.

Description

technical field [0001] The invention relates to the technical field of wireless radio frequency communication, in particular to a Doherty power amplifier based on an improved load modulation network to expand bandwidth and a realization method thereof. Background technique [0002] With the rapid development of wireless communication technology, radio frequency microwave technology is becoming more and more important in people's daily life. In order to transmit as much data as possible within a limited spectrum bandwidth, communication providers usually use very complex modulation methods, which will lead to a larger peak-to-average ratio (PAPR) of the signal, while using traditional power amplifiers such as class A, Class AB is very inefficient for amplifying non-constant envelope signals, especially at high power backoffs. The RF power amplifier with high efficiency and high linearity has become one of the research hotspots in academia and industry. Doherty power amplifi...

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Problems solved by technology

However, the Doherty power amplifier in the prior art has the problem of narrow bandwidth. The reason is that the load modulation network of the Doherty power amplifier in the prior art usually adopts the common 50 ohm quarter-wavelength impedance of the prior art. converter, its impedance transformation ratio is 4:1, which results in a large impedance transformation ratio, thus, greatly limiting the bandwidth

At the same time, the output impedance of the combined end of the traditional load modulation network is 25 ohms under different input powers. In order to match the load impedance, a microstrip line must be connected in series between the combined end and the load, which leads to the size of the Doherty power amplifier. increase, which limits its application in some occasions

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