6. (20%) Determine the small-signal voltage gain \( A{s} \) of the MOS amplifier shown in Fig. 6. The transistor has \( V{\mathrm{TH}} = 3\mathrm{V} \), \( k{n} = \mu{n}C{\mathrm{ox}}(W / L) = 0.25\mathrm{mA} / \mathrm{V}^{2} \) and \( \lambda = 0.02\mathrm{V}^{-1} \), and assume that the coupling capacitors \( C1 \) and \( C2 \) are sufficiently large to shorten the AC signals at their frequencies of interest, and \( A{s} \equiv -g{m}R{L} \), where \( R_{L} \) is AC equivalent resistance.