High-Linearity 60W Doherty Amplifier for 1.8GHz W-CDMA

A 5.5‐GHz SiGe HBT Doherty amplifier using diode linearizer and lumped‐element hybrid coupler

“…It represents the acoustooptic interaction frequency response and affects both the received and the reference signals. The equivalent normalized baseband representation of H 1 (f) is [5]:…”

“…On the other hand, to improve the linearity performances for practical purpose, some effective methods are proposed for Doherty amplifiers in previous publications [4 -10]. For example, Yang and coworkers reported bias optimization technique for 2.14 GHz N-way Doherty amplifier and Yamamoto presented impedance matching technique for 1.8-GHz Doherty amplifier in W-CDMA system [4,5]. In addition, Doherty amplifiers using feedforward linear method, post-distortion compensation method, and envelope tracking technique were realized with linearity enhancements in [6 -8], respectively.…”

Linearity and efficiency enhancement strategies for 4G wireless power amplifier designs

“…Multiple stages of the Doherty can be employed to realize even greater power saving benefits as the RF output power is reduced [33,34]. Although the Doherty amplifier topology was invented decades ago, it has enjoyed renewed interest recently for base station applications [35][36][37] and handset applications [38][39][40]. The load impedance presented to the transistor can be varied directly to adaptively modify the impedance presented to the transistor in response to the required output voltage.…”

Drain efficiency amplifier of 50% with optimized power range for CDMA base station

“…Doherty amplifier structure is generally known as a high-efficiency power amplifier [1][2][3], which is widely used in RF power amplifier systems for mobile communication system. The drain efficiency of the Doherty amplifier is the key of the RF power amplifier's efficiency, which remains close to its highest efficiency for a power range of 6 dB back-off from its saturated output power (Psat).…”