Impact of the amplifier-BandPass reconstruction filter interaction on the linearity of carrier amplitude-burst transmitters

Carrier amplitude-burst transmitters can ideally deliver 100% efficiency and perfect linearity. The amplitude to time conversion performed by a PWM or sigma-delta modulator allows the usage of switched mode power amplifiers, at the expense of introducing a large amount of out of band noise, which must be removed by a narrow bandwidth band-pass reconstruction filter. However, practical implementations suffer from several problems whose cause is the careless design of the amplifier-filter connection, which prevent the achievement of those ideal performance figures. This paper discusses how the linearity of these transmitters is affected by the interaction between the switched-mode amplifier and the band-pass reconstruction filter providing design rules for this amplifier-filter interconnection. The presented results are obtained by both simulations and practical measurements.

[1]  Yuanxun Ethan Wang,et al.  Pulsed Load Modulation (PLM) Technique for Efficient Power Amplification , 2008, IEEE Transactions on Circuits and Systems II: Express Briefs.

[2]  Yuanxun Wang.  An improved Kahn transmitter architecture based on delta-sigma modulation , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[3]  J. C. Pedro,et al.  A carrier-burst transmitter implementation: Design of bandpass filter and amplifier-BPF connection , 2012, 2012 Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits.

[4]  Genevieve Baudoin,et al.  Study of a polar sigma-delta transmitter associated to a high efficiency switched mode power amplifier for mobile WiMax , 2009, 2009 IEEE 10th Annual Wireless and Microwave Technology Conference.

[5]  Peter Singerl,et al.  Analysis of burst-mode RF PA with direct filter connection , 2010, The 40th European Microwave Conference.