A 5.5-GHZ SIGE HBT DOHERTY AMPLIFIER USING DIODE LINEARIZER AND LUMPED-ELEMENT HYBRID COUPLER

摘要

A 5.5-GHz Doherty amplifier using commercial 0.35-μm SiGe HBT technology is proposed in this article. To improve the linearity, a predistortion using diode linearizer is adopted for biasing the peak amplifier. Moreover, to realize in fully on-chip with circuit reduction, a 90° 3-dB hybrid coupler and quarter-wave transmission lines are implemented by lumped-elements. In this design, 819 μm{sup}2 HBTs are used for carried and peak amplifiers, respectively, and 26μm{sup}2 HBT is used for linearizer. Results verify that the power gain, P{sub}(1 dB), and power added efficiency (PAE) of the proposed Doherty amplifier at 5.5 GHz are 8.4 dB, 31 dBm, and 30%, respectively. Also, the adjacent channel power ratio (ACPR) and the output signal's spectrum mask are given using the 54Mcps 64QAM modulated signal at 10 MHz offset.