Compensation of two-periodic nonuniform holding signal distortions by using a variable FIR filter

We introduce a Farrow-based variable FIR filter to compensate distortions in digital-to-analog converters (DACs) that are due to two-periodic nonuniform holding signals. Without compensation such holding signals introduce distortions that reduce the DAC performance considerably. By utilizing a discrete-time model of a zero-order hold, we first derive the ideal frequency responses of the compensation filters. Then we exploit the spectral properties of the ideal frequency responses to introduce the design of a variable FIR filter that approximates the ideal response with low implementation complexity. Finally, a design example is provided.