Doherty power amplifier for broadening bandwidth based on improved load modulation network and implementation method thereof

Abstract

The invention provides a Doherty power amplifier for broadening a bandwidth based on an improved load modulation network and an implementation method thereof. A halving Wilkinson power divider is used for halving input power and separately outputting the halved input power to a main power amplifier circuit and an auxiliary power amplifier circuit, an output end of the main power amplifier circuit is connected with a 70.7 Ohm quarter-wave impedance transformer T1, the output end of the auxiliary power amplifier circuit is connected with a 70.7 Ohm quarter-wave impedance transformer T3, the power is output to a load after combination, and the combined output end is connected with a quarter-wave shorting stub T2 in parallel. Compared with the prior art, the load modulation network of the traditional Doherty power amplifier is improved, and the output end is connected with the quarter-wave shorting stub T2 in parallel, thereby reducing the impedance transformation ratio of the load modulation network, effectively inhibiting the drift of the load impedance with the frequency, and greatly broadening the working 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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