A low-power digital front-end direct-sampling receiver for flexible radios

Implementation of digital front-end (DFE) for direct-sampling receivers in 65-nm CMOS is presented. The DFE converts a digitized RF signal to a baseband signal, thereby realizing mixing and decimation. It supports fractional decimation from arbitrary RF carriers up to 2.7 GHz to any LTE baseband frequency. Measurements show that the DFE decimates a 16-MHz bandwidth signal centered at a 2.025 GHz carrier, to a baseband frequency of 20 MHz while dissipating 14 mW of power. Noise figure of the DFE is limited to 3 dB.