Amplifiers

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In multi-carrier power amplifiers, a feedforward technique is generally adopted due to its extremely linear and broadband characteristics. 1 However, the feedforward technique requires large circuits and is expensive because of its complexity. It uses two cancellation paths, and delay lines are inserted in each path to adjust the...

For the third-generation (3G) mobile radio standards, a very high linearity transmitter that can support high crest factor signals is necessary. High linearity and high efficiency are critical issues in amplifier design. In fact, as the power amplifier operates close to the saturation region where both high efficiency and...

Electrical memory effects are defined as changes in amplitude and phase of distortion components caused by modulation frequency. There are several ways of measuring memory effects. One of the most common is to plot the phase and amplitude of the distortion parameters with respect to the tone spacing in...

Multiple RF exciters feeding a broadband power amplifier and a broadband antenna system has become an increasingly popular form of system architecture throughout the frequency spectrum. This architecture, shown in Figure 1 , has several desirable features, the most popular of which is the reduced real estate requirement. Modern...

In the design of high frequency power amplifiers, one of the parameters is the stability of the active device. The stability of the active device is determined by the Rollet stability factor K. If K > 1, then the active device is unconditionally stable and the design of the...

Due to the fast development of wireless communications, a low cost, high performance, high integration technology is needed for system on a chip (SOC) implementation. The CMOS technology provides a good solution for SOC integration. 1 Recent improvements of the standard CMOS process make it possible to implement RF...

The number of mobile users is predicted to reach 1.7 billion by the year 2010. More than 45 percent of them will use high data speed services. W-CDMA, proposed by IMT2000, has become the most practical and important system for the development of new wireless communications. Nevertheless, second generation...

Atmospheric propagation attenuation is known to be higher in the 2.1 GHz band than in the cellular band. Thus, to overcome this performance disadvantage and to maximize cell coverage and capacity, Unity Wireless System's first feedforward multi-carrier linear power amplifier (MCLPA) product has been designed with a high 60...

Modern commercial and military communication systems require high efficiency, long term operating conditions. For this purpose, the power amplifiers, as final and highly current-consuming transmitter elements, are developed using the high efficiency class B, F or E modes of operation, depending on the technical requirements. In class B operation,...

GaAs HBT technology has been successfully deployed for low to mid-power MMIC RF amplifiers in recent years. EiC Corp. pioneered the use of an InGaP emitter for RF power amplifiers and first introduced gain block products in 1998. InGaP/GaAs HBT devices have proven to provide better performance and be...