High-Linearity Drive Amplifier Using Active Local Feedback

A drive amplifier consisting of a cascode amplifier and a local feedback amplifier is proposed to ensure high linearity. The local feedback amplifier with a post distortion technique compensates for the nonlinearity of a common-source stage while maintaining input impedance matching and a reasonable power gain. In addition, a process, supply voltage, and temperature (PVT)-compensated current mirror maintains a high OIP3 point over PVT variations. The theoretical analysis, simulation, and measurement are presented, showing good agreement. Measured results show an OIP3 of 27.2 dBm, OP1dB of 7.8 dBm with a power gain of 7.5 dB at 2.1 GHz, and power consumption of 22.2 mW at 1.8 V. The proposed DA is fabricated using a 0.11 μm CMOS process.