For the circuit shown below, assume that the transistor is in the active region. The transistor has a threshold voltage $V_t=0.4 \mathrm{~V}$ and a channel-length modulation parameter $\lambda=0.2 \mathrm{~V}^{-1}$. The bias current $I_D$ is $200 \mu \mathrm{~A}$ and the bias values of $v_{I N}$ and $v_O$ are both 0.9 V .



The transconductance of the transistor is