3a. Derive the small-signal fully-differential gain of the circuit. Assume λ = 0 for all transistors. Express your answers in terms of device small-signal parameters gm1, ro4, etc. Assume M3-M6 are identical, and all transistors are biased in the saturation region. Note that M3-M6 have identical bias conditions, thus have identical small-signal parameters. 3b. Repeat with λ > 0