Why CMOS? Output of all CMOS cells will be very close to rail-rail (may not be in case of Pass Transistor) With constant input to any cell, power dissipation is only due to leakage currents. Power dissipation increase if activity factor is more (Short circuit current + charging & discharging of load)

A System on Chip (SoC) is an integrated circuit that integrates all components of an electronic systems. It may contain digital, analog, mixed-signal, and radio-frequency modules—all on a single substrate. SoCs are very common in the mobile computing market because of their low power-consumption