Abstract
A 0.5V transformer folded-cascode CMOS low-noise amplifier (LNA) is presented. The chip area of the LNA was reduced by coupling the internal inductor with the load inductor, and the effects of the magnetic coupling between these inductors were analyzed. The magnetic coupling reduces the resonance frequency of the input matching network, the peak frequency and magnitude of the gain, and the noise contributions from the common-gate stage to the LNA. A partially-coupled transformer with low magnetic coupling has a small effect on the LNA performance. The LNA with this transformer, fabricated in a 90nm digital CMOS process, achieved an S11 of -14dB, NF of 3.9dB, and voltage gain of 16.8dB at 4.7GHz with a power consumption of 1.0mW at a 0.5V supply. The chip area of the proposed LNA was 25% smaller than that of the conventional folded-cascode LNA.
