Nonuniform-to-uniform decimation for delta-sigma frequency-to-digital conversion

Recently, a delta-sigma frequency-to-digital converter (FDC) capable of 14-bit audio bandwidth data conversion at a 10 MHz intermediate frequency (IF) was presented. The nonuniform-to-uniform decimation filter, a key component of this FDC, corrects for the nonuniform sampling inherent to the FDC and performs decimation filtering. This paper contains a detailed description of the nonuniform-to-uniform decimation filter and measured performance results for the entire FDC.