advertisment Advertisement
advertisment Advertisement
advertisment Advertisement
advertisment Advertisement

Amplifiers

An Adaptive Feedforward Amplifier for WCDMA Base Stations Using Imperfect Signal Cancellation

This article describes a new adaptive feedforward amplifier for a WCDMA system using an imperfect signal cancellation. Due to the complicated signal statistics, the distortion generated by the error amplifier is significantly reduced by an imperfect si...
As wireless systems evolve from second- to third- or fourth-generation, the linearity, efficiency and bandwidth requirements for power amplifiers become more stringent. Many techniques, including feedforward, envelope feedback and manifold types of predistorters, have been employed to effectively satisfy these performance requirements and to reduce the production costs for...
Read More

Design of a Predistorter Controlling Individual Orders of Intermodulation Using a New Harmonic Generator

A new type of predistortion linearizer is presented which uses individual orders of intermodulation to linearize a power amplifier. This new predistortion linearizer has two harmonic generators, each consisting of four diodes biased independently. Sinc...
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...
Read More

A Novel Adaptive Feedforward Amplifier Using an Analog Controller

A novel adaptive design for a feedforward amplifier linearizer with an analog controller is proposed in this article. Compared with previous adaptive linearizing methods, this new design does not require any pilot signal or intentional signal distortio...
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...
Read More

Memory Effect Reduction for LDMOS Bias Circuits

Memory effects have taken a very important role in today's design of base station power amplifiers. For example, they are responsible for limiting the cancellation when pre-distortion is applied to a power amplifier system.<sup>1</sup> This study show...
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...
Read More

A Method to Predict the Level of Intermodulation Products in Broadband Power Amplifiers

This article derives a formula to mathematically predict the level of intermodulation products generated in a broadband, multi-carrier power amplifier. The prediction method uses the level of a harmonic as a reference from which to extrapolate the leve...
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...
Read More

Effects of Grounding and Bias Circuit on the Performance of High Frequency Linear Amplifiers

The design of a high frequency amplifier is normally based on the S-parameters supplied by the manufacturer of the active device. However, in a practical design, these parameters are affected by the DC bias network and the grounding of the active devic...
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...
Read More

A 2.4 GHz CMOS Power Amplifier with 20 dBm Output Power for Bluetooth and WLAN Applications

This article presents a 2.4 GHz CMOS power amplifier (PA) with an output power of 20 dBm using a 0.25 ┬Ám 1P5M standard CMOS process. The PA uses a diode connected NMOS transistor functioning as a diode linearizer. It is believed that this is the first ...
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...
Read More

An RF Module Design for a Multi-mode Handset

This article describes a novel design of an RF module for a multi-mode handset and presents an example of an RF module for a W-CDMA/GSM/DCS tri-band and dual-mode handset. The entire module, including a direct modulation transmitter and a superheterody...
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...
Read More

A Minimalist Approach to Feedforward Multi-carrier Linear Power Amplifiers

A feedforward multi-carrier linear power amplifier with 60 W maximum average output is featured
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...
Read More

High Efficiency Class B, E and F Power Amplifiers: The Magic of Parallel Circuits

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,...
Read More

Sign-In

Forgot your password?

No Account? Sign Up!

Get access to premium content and e-newsletters by registering on the web site.  You can also subscribe to Microwave Journal magazine.

Sign-Up

advertisment Advertisement