Continuous-Time Digital Filters for Sample-Rate Conversion in Reconfigurable Radio Terminals

Abstract Reconfigurable radio terminals must cope with a multitude of master clock rates of diverse mobile communications air interfaces. Digital sample rate conversion (SRC) is an elegant way to enable the processing of signals with sample rates incommensurate to the clock rate of a nonsynchronized analog-to-digital converter. SRC is a process of resampling and thus, requires anti-aliasing filtering. The well-known Farrow-structure provides a means of implementing digital SRC on a parameterizable hardware platform enabling the adaptation to different rate change factors. Still, the Farrow-structure can only implement filters with poor anti-aliasing characteristics. The transposed Farrow-structure introduced in this article overcomes these problems and thus, represents a perfect means for SRC in reconfigurable radio terminals.