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HIGH POWER RF AMPLIFIER WITH LINEARIZER OF LARGE DYNAMIC POWER LEVEL RANGE

IP.com Disclosure Number: IPCOM000194648D
Publication Date: 2010-Apr-06
Document File: 4 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

A high power RF amplifier with linearizer for large dynamic power level range is disclosed. The present invention uses voltage controlled attenuators that are controlled by an input signal related voltage to compress the dynamic range of the detected signals input to a gain-and-phase detector (GPD). The proposed method utilizes GPD with a small dynamic range to control signals with big dynamic range.

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HIGH POWER RF AMPLIFIER WITH LINEARIZER OF LARGE DYNAMIC POWER LEVEL RANGE

FIELD OF INVENTION

The invention generally relates to radio frequency (RF) amplifiers and more particularly to amplifier linearization while utilizing a gain-and-phase detector (GPD).

BACKGROUND OF THE INVENTION

Gain-and-phase detectors (GPD) are usually used for amplifier linearization. Detectors which are widely used in digital communication do not have large dynamic range. The dynamic range is typically 60dB. For certain applications in digital communication which have a small dynamic range, the signals are not affected. However, some specific applications, such as Magnetic Resonance Imaging (MRI) have a signal with dynamic range as wide as 80dB. For applications with such wide dynamic range there is a possibility of high distortion levels.

In conventional methods consider, for example a transmission arrangement for a magnetic resonance apparatus. A transmission arrangement for a magnetic resonance apparatus comprises an input terminal, a high-frequency power amplifier and an antenna arrangement. A high-frequency input signal is amplified by the high-frequency power amplifier to produce a high-frequency output signal for supply to the antenna arrangement for emission. The high-frequency output signal is emitted as a magnetic resonance excitation signal. However, such conventional methods do not use detectors which are capable of handling high dynamic range of signals.

Hence there exists a need for a method for linear amplification which enables a detector to handle high dynamic range of signals.

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BRIEF DESCRIPTION OF THE INVENTION

The present invention uses voltage controlled attenuators that are controlled by an input signal related voltage to compress the dynamic range of the detected signals input to a gain-and-phase detector (GPD). This method uses GPD with small dynamic range to control signals with big dynamic range.

DETAILED DESCRIPTION OF THE INVENTION

In amplifier linearization according to the present method, a detector which is commonly used in digital communication applications is employed. The dynamic range of input and output signals is greater than the dynamic range of the detector employed. For example, the dynamic signal range can be 80db and the dynamic range of a detector may be 60db. In the present method, the dynamic range of the signals input to the detector is compressed according to the principle detailed below.

The circuit diagram of the present method is illustrated in Figure 1. The input and output sampled signals of the amplifier are shifted to a...