ASIC Processes UWB Baseband Signals

IMPULSE-RADIO ULTRA WIDEBAND (IR-UWB) targets low data rates in the range of 0.1 to 10.0 Mb/s. Recently, an application-specific integrated circuit (ASIC) for IR-UWB baseband signals was realized and characterized by David Barras, George von Bueren, and Heinz Jaeckel from the Swiss Federal Institute of Technology together with Robert Meyer-Piening from Sensirion AG and Walter Hirt from the IBM Zurich Research Laboratory.

This baseband ASIC, which is fabricated in 0.18-m CMOS technology, requires only 13 mW power during the initial acquisition and 6.5 mW during the signal-tracking phase at a pulse repetition rate (PRR) of 5 MHz. The incoming baseband signals result from the direct downconversion of IR-UWB RF pulses. Those pulses are modulated by a binary-frequency-shift-keying (BFSK) scheme. Unlike other projects, this ASIC's analog front end does not rely on the use of high-speed analog-todigital converters (ADCs). Instead, it leverages a non-coherent demodulation method followed by a simple integrate-and-dump detection, which has been realized with analog circuitry.

The researchers' goal was to reduce power consumption by avoiding the implementation of Nyquist-rate ADCs and digital signal processors (DSPs) running at full speed to process the received signal. This implementation also provides the advantage of scalable power consumption with the received PRR. Measurements with the front-end curve in a bit-error-rate (BER) curve exhibit sensitivity of 83.7 dBm. This value roughly corresponds to a communication distance of 10 m in free space without any error correction or any other coding schemes. See "A Low-Power Baseband ASIC for an Energy-Collection IR-UWB Receiver," IEEE Journal Of Solid-State Circuits, June 2009, p. 1721.

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