Multi-finger MOSFET low noise amplifier performance analysis

The Multi-finger layout technique has been extensively used in Nano-scale CMOS circuit design due to the increased circuit performance compared to a single finger layout. However choosing a finger width and number of fingers to optimize circuit performance is a challenging problem. In this paper the performance of a 2.4GHz single ended low noise amplifier (LNA) with a fixed total transistor width in 90nm CMOS technology is analyzed as function of number of fingers (N_f). The results show that the drain to source current (I_ds), transconductance (g_m) and effective gate capacitance (C_geff) increase with increasing N_f. The effect of N_f on transistor cutoff frequency (f_T) and LNA noise figure (NF), voltage gain (AV), center frequency (f_C), and impedance/noise matching is presented.