A magnetic feedback method for enhancing the reverse isolation of low-voltage (1.2-V), single-transistor CMOS low-noise amplifiers (LNAs) is presented. The method neutralizes the gate–drain overlap capacitance of the amplifying transistor, allowing for adequate reverse isolation without gain reduction. The method does not require a differential LNA topology and input matching is facilitated since the degeneration inductor is not a part of a magnetic feedback loop. In addition, it allows for neutralizing the intrinsic part of the parasitic capacitance, which cannot be neglected in short-channel devices. Simulation results utilizing a standard 0.18-$mu$m CMOS process indicate a 17–29-dB improvement in the reverse-isolation performance with minimal noise figure deterioration.
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