A Broadband Doherty Power Amplifier With a New Load Modulation Network

Abstract

In this paper, we proposed a new load modulation method to improve bandwidth and efficiency at output power back-off (OBO) of the Doherty Power Amplifier (DPA). The quarter wavelength transmission line behind the combination point of the impedance inverter was replaced with a dualfrequency matching circuit to matche the impedance value of the combination point to the load impedance in this method. The dual-frequency matching was used to compensate for the frequency dispersion effect that occurs in the traditional impedance inverter network and to a certain extent solves the bandwidth limitation of the Doherty power amplifier. To verify the proposed theory, a broadband high-efficiency power amplifier was designed and manufactured for 5G mobile communications. Measurement results show that the designed DPA is in the range of 2.4-3.7GHz, the saturated output power is above 42dBm, the saturated drain efficiency is 61.2%-68.4%, and the 6dB back-off efficiency is 49.7%-61.4%.INDEX TERMS Doherty, load modulation network, dual-band, broadband, high efficiency, 5G

Modular Design and Characterization of a Reconfigurable Sequential Power Amplifier

“…To this aim, Doherty PAs employ load modulation, usually implemented with an impedance transformer, and this is widely accepted as a bandwidth limiting factor. Parallel impedance transformers [4], dual-frequency matching [5] can be used to improve the bandwidth limitation of the Doherty PA.…”

A concurrent 2.6/3.5GHz dual-band Doherty power amplifier with matching network based on composite right/left-handed unit cell

“…However, these techniques lead to the signal having large peak-toaverage power ratios (PAPRs), which significantly reduces the efficiency of power amplifier (PA) at power back-off. To solve this problem, DPA, which was first proposed in 1936 [4], is considered to be a popular solution because of its high efficiency at both saturation and OPBO [5,6,7,8,9,10,11,12]. On the other hand, the traditional single-frequency communication system has been unable to meet the current complex communication needs.…”

A 47 % Fractional Bandwidth Sequential Power Amplifier with High Back-off Efficiency

“…However, the classical DPA approach remains band-limited because of the utilisation of quarter-wave transmission lines for impedance transformation which also aids in active load modulation. This despite the adoption of bandwidth improve- ment methods such as parallel impedance transformation [5] or dual-frequency matching [6].…”