The effect of receiver front-end non-linearity on DS-UWB systems operating in the 3 to 4 GHz band

The paper presents a performance analysis of direct sequence ultra wideband (DS-UWB) systems operating with non-linear receiver front-ends. Following this analysis, we propose the novel use of pulse doublets to mitigate non-linearity induced distortion. The signal-to-noise-and-distortion ratio (SNDR) and bit error rate (BER) are evaluated with varying degrees of non-linearity and interference power. Simulation results indicate significant performance improvements by using pulse doublets under high interference power and non-linear operating conditions. Using pulse doublets allows reduced front-end linearity requirements and enables improvements in more critical circuit parameters. Front-end modules, such as low noise amplifiers (LNAs), mixers and baseband amplifiers, are designed using Peregrine´s 0.5 μm SOS-CMOS process to demonstrate the benefits of circuits designed with relaxed linearity requirements. Simulation results obtained using the Cadence Spectre RF simulator indicate that the sub-linear front-end achieves 33 dB increase in voltage gain, 2 dB improvement in noise figure, 64% saving in power and 917 MHz extension in bandwidth over its more linear counterpart.