Desensitized design of MOS low noise amplifiers by Rn minimization

We show that the minimization of device R_n allows us to simultaneously approach noise and input match in CMOS LNA designs in a topology independent fashion. The dependence of R_n on designer specifiable parameters is derived using a theoretical analysis of long channel (i.e square-law) devices. Experimental results are shown to confirm this dependence for short-channel devices. Using experimental data from a 0.18 μm technology, we show that a low R_n design results in a ≥2× increase in the bandwidth over which an optimal noise figure can be obtained. The desensitization of the device with a low R_n provides a greater immunity to impedance mismatches, modeling errors and manufacturing variations.