Exercise 4.5 AN NMOS amplifier circuit

See the amplifier circuit below. Assume that $M_1$ is biased in the square law region with drain (bias) current $I_{D1}$. Assume inductors and capacitors can be modelled as opens and shorts for the signal frequency.

a)

Is this an inverting or a non-inverting amplifier? Motivate your answer.

b)

Draw a proper small-signal equivalent circuit.

c)

Derive an expression for the voltage gain $a_v=v_{\mathit{out}}∕v_{\mathit{in}}$

d)

Derive an expression for the input resistance $r_{\mathit{in}}$.