This is where an "interpolating DAC" is invaluable. An interpolating DAC accepts external data at fc but uses an internal phase-locked loop (PLL) to generate the higher clock rate Kfc , which is used to clock the DAC. Of course the DAC requires updating at the new clock rate - the extra data points are generated in a very simple DSP processor called a digital interpolation filter, which is, in essence, a low pass filter which adds extra zero data points to the incoming data stream and then removes all the HF spectral components generated by the operation. The small extra complexity, cost and power consumption of an interpolating DAC is amply compensated by the savings in external system complexity, power and performance losses.