In order to determine the operating limits of charge-coupled devices, a model that approximates the charge-coupled device with a traveling sine wave potential has been analyzed for operating power and losses attributable to surface states. The model has been applied to a 16-bit, four phase, CCD shift register with an active area of 0.0015 mm
2per bit, and it gives the following predictions: Surface state losses with a 10-MHz clock will amount to approximately 1.1%/bit (at

/cm
2eV) when an input signal level of 10
-12coulomb is used in an n-channel device. Higher or lower signals, or a p-channel structure will lead to higher losses. Under the same conditions, the real driving power can be no less than 7 µwatts/active bit, and reactive driving power, expressed as reactive volt-amperes, is 26 µwatts/empty bit and 230 µwatts for a charged bit. The applicability of these results to the realizable device will be shown.