Simulation of Four-Stage Doherty Power Amplifier Structure

Abstract

In order to improve the efficiency of Digital TV transmitter, we uses a new type of four-stage Doherty structure. Based on the transmission line theory and active loadpull theory, we deduce the principle of the four-stage Doherty structure, and use ADS to design a four-stage Doherty power amplifier. The simulation result shows that this four-stage Doherty PA has an efficiency of 34% at 6dB back-off (53dBm) for DVB-T OFDM 64 QAM modulated signal. The ACPR and MER obtained at 53dBm when output power are 31dBc and 28dB respectively.

Design of a DPA based on the dual‐level supply voltage modulation for efficiency improvement

“…However, one of the common problems with conventional DPAs is that the power added efficiency (PAE) is not satisfactory at low power RF input ; therefore, to improve the PAE of DPAs is one of the hottest research areas in PA designs. One of the direct ways to enchance PAE is employing N‐way ( N > 2) or multistage structures, but the circuits' complexity and fabrication cost can sometimes be greatly increased. Moreover, linearity can be deteriorated using multiple PAs.…”