A 70 pJ/Pulse Analog Front-End in 130 nm CMOS for UWB Impulse

Abstract

This paper presents an integrated ultra-low power analog front-end (AFE) architecture for UWB impulse radio receivers. The receiver is targeted towards applications like wire- less sensor networks typically requiring ultra energy-efficient, low data-rate communication over a relative short range. The pro- posed receiver implements pulse correlation in the analog domain to severely relax the power consumption of the ADCs and digital backend. Furthermore a fully integrated prototype of the analog front-end, containing a PLL, programmable clocking generator, analog pulse correlator , a linear-in-dB variable gain amplifier and a 4-bit ADC, is demonstrated. Several design decisions and techniques, like correlation with a windowed LO instead of with a matched template, exploiting the duty-cycled nature of the system, operation in the sub-1 GHz band as well as careful circuit design are employed to reach ultra-low power consumption. The analog front-end was manufactured in 130 nm CMOS and the active circuit area measures 1000 m 1500 m. A maximum channel conversion gain of 50 dB can be achieved. Two symbol rates, 39.0625 Mpulses per second (Mpps) and 19.531 Mpps are supported. The AFE consumes 2.3 mA from a 1.2 V power supply when operating at 39.0625 Mpps. This corresponds to an energy consumption of 70 pJ/pulse. A wireless link over more than 10 m in an office-like environment has been demonstrated at 19.531 Mpps with a PER /49/69 /51under direct LOS conditions.