A Doherty Power Amplifier with Large Back‐Off Power Range Using Integrated Enhancing Reactance

Abstract

A symmetric Doherty power amplifier (DPA) based on integrated enhancing reactance (IER) was proposed for large back-off applications. The IER was generated using the peaking amplifier with the help of a desired impedance transformation in the low-power region to enhance the back-off efficiency of the carrier amplifier. To convert the impedances properly, both in the low-power region and at saturation, a two-impedance matching method was employed to design the output matching networks. For verification, a symmetric DPA with large back-off power range over 2.2–2.5 GHz was designed and fabricated. Measurement results show that the designed DPA has the 9 dB back-off efficiency of higher than 45%, while the saturated output power is higher than 44 dBm over the whole operation bandwidth. When driven by a 20 MHz LTE signal, the DPA can achieve good average efficiency of around 50% with adjacent channel leakage ratio of about –50 dBc after linearization over the frequency band of interest. The linearity improvement of the DPA for multistandard wireless communication system was also verified with a dual-band modulated signal.

A 9 dB back‐off dual‐band asymmetric Doherty power amplifier using dual peaking amplifiers for reactance compensation

“…To achieve a higher BOP range, two peaking amplifiers were employed for asymmetric Doherty configuration. For bandwidth extension, the reactance compensation method was used 10–12 . However, different from conventional designs, two parallel peaking amplifiers using the low‐order impedance transformation network (ITN) were combined to generate the desired compensating reactance at the BOP range for wideband operation.…”

“…For bandwidth extension, the reactance compensation method was used. [10][11][12] However, different from conventional designs, two parallel peaking amplifiers using the low-order impedance transformation network (ITN) were combined to generate the desired compensating reactance at the BOP range for wideband operation. Experimental results show that high efficiency at 9 dB BOP range within a wide frequency band can be achieved using the proposed design method.…”