An integrated circuit (IC) in a modern smartwatch contains a massive number of silicon MOSFETs.
State the name of the insulating material layer within an enhancement-mode N-channel MOSFET's structure that prevents gate current from flowing, resulting in an extremely high input resistance.
The CPU inside the smartwatch contains 4.5×1094.5 \times 10^{9}4.5×109 integrated MOSFET transistors. An individual discrete MOSFET of a similar class has a typical standby leakage current, IDSSI_{DSS}IDSS, of 5.0 nA5.0\text{ nA}5.0 nA.
The smartwatch is powered by a battery with a capacity of 380 mA h380\text{ mA h}380 mA h. A fully charged battery of capacity 1 A h1\text{ A h}1 A h allows 3600 C3600\text{ C}3600 C of charge to flow. The manufacturer specifications state that the smartwatch can remain on stand-by on a single full charge for ≈72 hours\approx 72\text{ hours}≈72 hours.
Discuss, using a calculation of the potential standby time if all integrated transistors leaked 5.0 nA5.0\text{ nA}5.0 nA, why the leakage current of the individual MOSFETs on the CPU chip must be vastly smaller than that of the discrete MOSFET.