Analysis and optimization of packaged inductively degenerated common-source low-noise amplifiers with ESD protection

The effects of packaging in inductively degenerated common-source low-noise amplifiers (LNAs) with electrostatic discharge (ESD) protection are studied and the performance of the packaged LNA is optimized. Equations describing the input impedance, transconductance, voltage gain, and noise figure (NF) of the packaged amplifier are derived and the effects of the LNA input matching network, package, and ESD parasitics on these amplifier quantities are highlighted. From the equations, several design guidelines for the packaged LNA are obtained and a systematic approach for the ESD-protected LNA optimization is deduced. It is also shown that, in the presence of an equivalent parallel package parasitic capacitance C_p, the NF in a well-optimized LNA is easily dominated by the losses of the input-matching network instead of the active device noise. Based on the theoretical results, a packaged inductively degenerated common-source LNA with ESD protection is designed in a 0.13-μm CMOS process. The amplifier provides a forward gain (S₂₁) of almost 18 dB at 2 GHz with an NF of 1.6 dB while consuming 8.4 mW from a 1.2-V supply.