S-band Linear Power Amplifier Design And Realization

With the development of modern communication technology, the frequency resource became more and more important.For using the limited frequecy resource efficiently,multi-carrier technology is adopted in communication systems.Take the third general communication system WCDMA for example, which use the brand band modulation and multi-carrier technology, this system requires high linearity power amplifier to assure the ACLR. On consider of the cost and cooling part, the efficiency is also a critical factor. On this situation Doherty and feedforward technology is the best choice.This paper firstly analyses the unlinearity characteristic of power amplifier in theory, then construes and summarizes the advantages and disadvantages of linear technology which is uesed in comman situation. Especially, this paper introduces Doherty and feedforward echnology in theory and practice. On the demand of the RF specifications in 3GPP for WCDMA transmitter power amplifier, using EDA tools such as ADS, I simulated and designed a feedforwad power amplifier system.Test results show that under 2-tone test in 5MHz tone spacing, the power amplifier system achieves -50dBc ,and the result of APCR is beyond -53dBc.Theoretically,those result meet the target of demands of WCDMA system and inrease linearity of the transmitter markedly.