A digital Cartesian feedback path design for 2.4GHz ISM band standards

A digital radiofrequency (RF) transmitter (TX) architecture for software defined radio (SDR) is proposed in this paper. Nowadays the tendency is to integrate many telecommunication standards within a unique circuit. This leads to consider reconfigurable transmission architectures which contain a minimum of analogue components. To address the non linearity issue posed by the power amplifier (PA), an adaptive baseband digital predistortion mechanism was favored for its stability and software reconfigurability. The subsequent predistortion algorithm collects the data from the PA trough a dedicated feedback path. In the State-of-the-Art proposed feedback paths are not reconfigurable. Either they contain analogue filters. In proposed feedback path, the filtering is performed by charge sampling at the entrance of analog-to-digital converter (ADC). We present the analysis and model of the proposed feedback path. The scaling of ADC resolution and bandwidth for the most stringent standard in ISM 2.4 GHz band is reported.