In the circuit, \( I_{\text{DC}} \) is an ideal current source, the transistors \( M_1 \), \( M_2 \) are assumed to be biased in saturation wherein \( V_{\text{in}} \) is the input signal and \( V_{\text{DC}} \) is the fixed DC voltage. Both transistors have a small signal resistance of \( R_{ds} \) and transconductance of \( g_m \). The small signal output impedance of the circuit is:
