In this paper, a quasi-asymmetric Doherty power amplifier (PA) is designed without load modulation using the GaAs 0.25𝜇𝑚 pHEMT technology to reach an enlarged output power backoff (OPBO) with circuitry solutions in order to overcome technology restrictions. To prevent power leakage in auxiliary PA (PAaux) due to its extremely large off-state impedance, a Wilkinson power combiner is added to the output. Moreover, an input asymmetric power divider is designed to guarantee that no considerable power is delivered to main PA (PAmain) in the high-power region to make it saturated. A two-section matching network is proposed for PAmain, which simultaneously compensates for phase differences of the main and auxiliary amplification paths.To control the significant impedance variation of PAaux versus sweeping power and the different impedance trajectories of the main and auxiliary amplification paths, the bias and dimension selection of PAaux are analyzed to reach the desired output power profile versus input power. These methods overcome impedance variations and linearity degradation. To achieve the aimed 10% fractional bandwidth, appropriate low-quality LC-networks are selected as matching networks.The simulation results indicate the utility of the proposed structure for microwave link applications. Continuous-wave simulations imply that the Doherty PA has a 33dBm maximum output power and a 13.5dB power gain with less than 1dB power gain compression in the desired
A novel high CMRR current output stage (COS) with QFG is presented in this paper. A novel common mode feedback (CMFB) is used to reject the common mode signal in order to achieve high CMRR. The common mode signal is omitted by the technique of adding the main signal and its opposite polarity one. 112 dB of CMRR is obtained in 0.35 µm CMOS technology with ±0.75 v supply voltage and only 182µw power dissipation which shows good improvement compared to the other work in the literature
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